23-es.2.14.0015 rev a - lv switchgear & controlgear for use qatar

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CONTENTS

1.0 Introduction

2.0 Custodian

3.0 Purpose

4.0 Application

5.0 Scope5.1 Definition of non-technical terms5.2 Definition of technical terms5.3 Guarantee and warranty

6.0 Service and Environmental Conditions6.1 Ambient temperature for design purposes

7.0 International Reference Standards

8.0 General Requirements8.1 The Manufacturer’s product range8.1.1 Product service life8.1.2 Offshore and marine installations8.2 Origin of main power components8.3 Project management8.4 Abbreviations of some technical terms used herein8.5 Derating factors and ratings8.5.1 Derating factors for normal service8.5.2 Short circuit ratings8.5.3 Rated diversity factor8.6 Voltage and frequency variations8.7 Type Test certification8.8 Radio Frequency Interference Limits

9.0 Common Design and Construction Requirements9.1 Enclosure and component degrees of ingress protection9.1.1 The switchgear9.1.2 The bus bar ducting9.2 General features of enclosures9.3 Safety9.3.1 Test reports for internal arcing faults9.3.2 Safety shutters9.3.3 Power switches and isolators9.3.4 Remote operation of switching devices9.3.5 Modes of operation9.4 Interrupting medium of circuit breakers and contactors9.5 Interchangeability9.6 Spare cubicles and extendibility

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9.7 Bus bars9.7.1 Transformer incomer neutral earthing9.7.2 Generator incomer neutral earthing9.8 Bus bar ducting9.9 Earthing facilities for the enclosure9.10 Interface panels9.11 Connection of QGPC's cables9.12 Gland plates9.13 Basic interlocking9.14 Internal wiring9.15 Internal wiring terminals9.16 Floor frames9.17 Padlocking facilities9.18 Manual operation equipment9.19 Anti-condensation heaters9.20 Labelling9.20.1 Labelling of components.9.20.2 General equipment nameplate9.21 Painting9.22 Handling trucks9.23 Special tools and lifting facilities

10.0 Circuit Breakers10.1 Functional requirements10.1.1 Operating mechanisms10.2 Circuit earthing10.2.1 Incoming circuit earthing10.2.2 Outgoing circuit earthing

11.0 Contactor Motor Starters and Contactor Feeders11.1 All contactors11.2 Additional requirements for motor starters11.3 Additional requirements for feeder contactors11.4 Manually switched feeders11.5 Isolating devices or disconnectors

12.0 Components12.1 Electrical protection relays12.1.1 Additional requirements for motor starters12.1.1.1 Motor overload protective relays and thermistor control units12.1.1.2 Motor earth fault protection12.1.1.3 Motor restarting facilities12.2 Indicating instruments12.3 Indicating lamps12.4 Current transformers12.5 Voltage transformers12.6 Fuses for LV circuits12.7 Neutral links for LV circuits12.8 Earth links for LV circuits12.9 Control relays and control contactors12.10 Interposing control relays12.11 Push-button devices

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12.12 Auxiliary contacts for the power circuit breakers and contactors12.13 Test facilities12.14 Heat emission12.15 Control circuit and auxiliary circuit voltage supplies12.15.1 A.C. and D.C. voltages12.15.2 Moulded case and miniature circuit breakers

13.0 Inspection

14.0 Testing specifications14.1 General14.2 Type tests14.3 Witnessed routine testing

15.0 Documentation15.1 Design documents to be provided by the Manufacturer15.1.1 Tender Documentation15.1.2 After the Purchase Order has been placed15.2 Instructions for delivery, installation, operation and maintenance

16.0 Packing

17.0 Approval to Deviate

18.0 Revision History Log

19.0 Bibliography19.1 Common references19.2 Technical references19.3 QGPC documents19.4 Periodic Revision of Reference Documents

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Appendices

A. Minimum Circuit Equipment ListsA.1 Low voltage generator incomers.A.2 Transformer incomers, primary circuit for solid earthed secondary windings.A.3 Transformer incomers, secondary circuit for solid earthed secondary windings.A.4 Plain incomers and interconnectors.A.5 Bus-section circuit breakers.A.6 Motor starter feeders using circuit breakersA.7 Motor starter feeders using fuses and contactors A.8 Static load feeders using fuses and contactors

B. Interlocking for Dual Feeders to SwitchboardsB.1 Momentary paralleling interlocking schemesB.2 Interlocking schemes for the incoming feedersB.3 Interlocking schemes for bus-section circuit breakers

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1.0 Introduction

This is an engineering specification, which gives details about the Low Voltage Switchgearand Controlgear for use indoors in non-hazardous environments.

Note that any changes to this document from its last revision are highlighted by a boldvertical bar to the left of each area of change. Should there be a need to consult thisdocument’s change history log, refer in the first instance to its custodian (EE). Referencesmade throughout this specification to international standards and the like are numbered insidesquare brackets [ ] and may be found in the Bibliography (19).

Cross references between sections and sub-sections within this specification are numberedinside round brackets ( ).

The manufacturer, and QGPC, should take note of the technical and documentationrequirements described herein for the tendering stage of any enquiries. These are highlightedby the word ‘tender’, or its derivatives, by being printed in bold typeface.

2.0 Custodian

The Custodian of this specification is EE, who is responsible for the accuracy and quality ofits contents and for its future revisions, where these are required to reflect industry trends orchanges to QGPC business practices.

3.0 Purpose

The purpose of this specification is to describe the QGPC requirements for industrial typemetal-enclosed switchgear and control-gear, based on the requirements of IEC 439 [26] andIEC 947 [36] in particular.

4.0 Application

This specification shall be applied to equipment which will be located indoors in purposedesigned switch-rooms; and installed at QGPC oil and gas processing plants, refineries,chemical plants, LNG plants, offshore platforms, industrial sites, and the like. QGPCpersonnel and their approved consultants and contractors shall use this specification topurchase new equipment, and for extending existing switchgear and controlgear, located inboth existing and new plants.

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5.0 Scope

The manufacturer shall inform QGPC in writing, at the tendering stage, of any deviationfrom the technical requirements of this specification. Otherwise QGPC will consider that themanufacturer complies with these technical requirements and will be manufacturing theequipment accordingly.

This specification covers a range of equipment having nominal voltages up to approximately600 volts as described in IEC 38 [10], and frequencies of 50 or 60 Hz, see also (8.6).

5.1 Definition of Non-Technical Terms

For the purposes of this document the following definitions of terms and interpretations shallapply regardless of any other meaning the words may have in other respects.

Shall. The word shall is to be understood as mandatory.

Should. The word should is to be understood as being strongly recommended.

QGPC Is the Qatar General Petroleum Corporation (QGPC) which ultimatelypays for the switchgear. QGPC will generally specify the technicalrequirements. QGPC may also include an agent or consultant to act on itsbehalf.

Manufacturer Is the party which manufactures or supplies equipment and services toperform the functions required in this specification.

Free-issue. Equipment purchased by QGPC from a third party. This equipment shallbe installed in the SWGR by the manufacturer.

Inspection. This shall be taken to mean a visual inspection of the equipment andinstallation.

Testing. This shall be taken to mean the type tests and routine tests normallycarried out at the factory of the manufacturer.

Calibration. This shall be taken to mean the special testing of measuring devices andcontrol systems. This is necessary to verify the characteristics of theequipment, and to fix the settings and adjustments before the equipment isput into normal service.

Commissioning. This shall be taken to mean energisation and the final tests and checks atthe QGPC’s site subsequent to the energisation necessary to ensure thateach circuit satisfactorily performs its function.

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5.2 Definition of Technical Terms

For definitions of technical terms pertaining to LV switchgear and controlgear refer to IEC947 [36] Part 1 section 2.1 and IEC 50 [11].

5.3 Guarantee and Warranty

The guarantee and warranty requirements shall be described in the project documentation.

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6.0 Service and Environmental Conditions

The atmosphere throughout all QGPC plants shall be considered to be corrosive, as normallyassociated with oil and gas processing plants, refineries, chemical plants, LNG plants, off-shore platforms, industrial sites, and the like. In addition, for offshore and coastal locations,the atmosphere shall be considered as salt laden.

High humidity is experienced in all areas and condensation will occur on all equipment duringsome period of its lifetime and therefore all components, nuts, bolts and washers etc. shall beof corrosion resistant material except where specifically stated otherwise and shall betropicalised.

6.1 Ambient temperatures for design purposes

The ambient air temperatures for enclosed modules and equipment rooms shall generally bewithin defined conditions as dictated by the heating and ventilation (HVAC) system, see c)below. However, to satisfy conditions that may occur when the HVAC is inoperative theinternal ambient air temperatures shall be considered as a maximum of 45 deg C.The manufacturer shall take this into account when calculating, and quoting, derating factorsfor normal rated currents and for fault currents of the main power components, e.g. bus bars,droppers, circuit breakers, contactors. The manufacturer shall quote all ratings at 45 deg C. Inthis regard the manufacturer shall describe in his tender documents what alterations will bemade to his design to accommodate 45 deg C, as against 40 deg C as recommended by IEC947 [36] section 6.1.1.

The following ambient temperatures are used as general design conditions and are extractedfrom the QGPC document ES.2.03.0001 [50], which gives more detail : -

a) Halul Island and offshore platforms.

Design summer dry bulb : 43 deg C.Maximum summer dry bulb : 45 deg C.

b) Messaieed, Dukhan, Ras Laffan and other land-based installation.

Design summer dry bulb : 43 deg C.Maximum summer dry bulb : 48 deg C.

The SWGR will normally be located in a dedicated room provided with HVAC.

c) Atmospheric conditions for indoor installation.

The atmospheric conditions inside the switch-room shall generally be in accordancewith IEC 947 [36] section 6.1.3. However, allowance shall be made for the entry ofdust, salt, and sulphur contaminated air when the doors are open or cable entrancesthrough the floor are uncovered during maintenance and construction periods. TheHVAC system should maintain the air temperature at no greater than 25 deg C witha relative humidity of 55 %. When the HVAC is out of service the humidity mayreach 95 % for long periods of time, in which case the performance of the SWGRshall not be affected.

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Depending on the area where the SWGR will be installed, condensation inside theSWGR during the above periods cannot always be excluded. Proper measures e.g.by installing panel heaters shall be considered. Components affected by highhumidity shall be tropicalised.

d) Atmospheric conditions for outdoor installation.

The air can be laden with dust, salt or sulphur as encountered in the petrochemicalindustries or in oil fields and condensation as a result of high humidity shall beconsidered.

All equipment shall be capable of accommodating a transportation horizontalacceleration of 0.8 g in any direction and a vertical acceleration of 1.0 g plus orminus 0.5 g.

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7.0 International Reference Standards

See section (19) ‘Bibliography’ for a complete list of reference documents.

The international standards IEC 439 [26] and IEC 947 [36] shall take precedence over otherreferenced standards.

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8.0 General Requirements

8.1 The Manufacturer’s Product Range

It is a general requirement that the manufacturer offers only equipment that is within hisstandard range of equipment, and that such equipment is not scheduled to be withdrawn fromproduction within 5 years of it being installed at the QGPC site. Any equipment that is‘bought-in’ from a third party shall also be from a standard range of products from the thirdparty, but subject to the approval of QGPC. The equipment shall not be a proto-type or a newproduct-line that has not been sold in reasonable numbers to similar users as QGPC. Themanufacturer shall include in his tender documentation a list of users in the Middle Eastregion that have purchased the same equipment being offered.

8.1.1 Product Service Life

The switchgear shall be designed for a service life of at least 20 years in the ambientconditions of Qatar. The switchgear shall be suitable for a minimum of 3 years of normalservice operation from the time it is installed and commissioned, without maintenance at theduty specified on the data sheets.

8.1.2 Offshore and Marine Installations

Switchgear to be installed on offshore platforms and marine vessels may be subjected to shockand vibration associated with drilling and production facilities, and to the deflection of thedeck or floor on which the switchgear is mounted. Switchgear on mobile offshore installationsshall be suitable for operating whilst being inclined (e.g. trim or list). It shall be suitable foroperating in the presence of acceleration forces and the effects of speed and motion of theinstallation.

8.2 Origin of Main Power Components

The manufacturer shall offer main power components e.g. circuit breakers, contactors, bus-bar assemblies, power cable terminations, tier steel-work, that are all manufactured by themanufacturer in one country; preferably the one country where the purchase order will bemanaged by the manufacturer. Type Test certificates shall be in the name of the manufacturerfor the SWGR, and not in the name of a third party manufacturer or vendor. Themanufacturer shall confirm this paragraph in his tender documentation.

8.3 Project Management

The manufacturer shall nominate a single person to manage the project and this person shallbe the single ‘focal point’ for all discussions, meetings, communications, correspondence, andthe like, between the manufacturer and the QGPC. This nominated ‘focal point’ shall declaredin the manufacturer’s tender documents, and he shall be available to discuss all technicalaspects of his tender and this specification.

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8.4 Abbreviations of Some Technical Terms Used Herein

The definitions for some technical words and abbreviations used in this specifications are:-

COMPARTMENT Space dedicated for one specific functionor CUBICLE e.g. motor starter, circuit breaker.

TIER A vertical group of compartments of single width with a bus barchamber at the top, a bus bar dropper (riser) chamber at the side orrear, and a wire way at the side.

SECTIONS Two or more tiers connected either side-to-side or back-to-back thatwill be shipped from the manufacturer’s works to the job site as asingle entity.

ENCLOSURE The steel casing that encloses the complete switchboard. The enclosuremay consist of tiers or sections as described above. The enclosure mayalso be termed the ‘assembly’.

SWGR The complete switchboard comprising all compartments, cubicles,tiers, sections, control gear etc. that comply with the purchase order.

TRUCK The moveable part of the compartment or cubicle to which ispermanently attached the CB or contactor.

DATA SHEETS This includes all relevant data sheets, diagrams and drawings issuedwith the enquiry or purchase order package.

A.C. or a.c. Alternating current or voltage.

BSI British Standards Institution.

CB Circuit breaker.

CCR Central control room.

CT Current transformer.

D.C. or d.c. Direct current or voltage.

DCS Distributed control system

deg C Degrees Celsius.

DOL Direct-on-line starting of induction motors.

ELCB Earth leakage circuit breaker.

EMI Electromagnetic interference.

ESD Emergency shut down.

FAT Factory acceptance testing.

F & G Fire and gas detection and control system.

HRC High rupturing capacity.

HV High voltage, above 600 volts.

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HVAC Heating, ventilation and air conditioning.

Hz Frequency of alternating current or voltage, cycles per second.

IEC International Electrotechnical Commission.

LED Light emitting diode.

LMS Load management system.

LSS Load shedding system.

LV Low voltage, 51 to 600 volts.

MCB Miniature circuit breaker.

MCC Motor control centre.

MCCB Moulded case circuit breaker.

MMI Man machine interface, e.g. computer keyboard.

PMS Power management system.

Pk Peak value of instantaneous current or voltage.

RMS Root mean square value of current or voltage.

SCADA System control and data acquisition.

S.I. System International.

SWGR Switchgear and controlgear

SWBD Switchboard

VT Voltage transformer.

The switchgear and control gear (SWGR) comprising a free-standing switchboard assemblyshall be a factory-assembled, metal-enclosed, arrangement incorporating circuit breaker ormixed assemblies of circuit breakers, motor starters and contactor devices, which mayincorporate disconnectors (isolators) or earthing switches. For the purposes of thisspecification, fused-protected motor starters and contactor devices will be referred to ascontactors. The whole assembly will be called the switchgear (SWGR) or the switchboard(SWBD).

8.5 Derating Factors and Ratings

8.5.1 Derating Factors for Normal Service

The SWGR normal service rating shall be as given on the data sheets. The requirement of(6.1) shall apply. The manufacturer shall describe in his tender documents all derating factorsthat he has applied for the normal service ratings.

Cooling fans shall not be used to enable the SWGR to meet the requirements of QGPC.

The heat created within the SWGR shall be dissipated from the enclosure by natural means,e.g. conduction, convection, radiation, without the need for louvres, grills or ventilationopenings. The cross-sectional area of conductors carrying the main power circuit currentsshall be large enough to ensure that the above-mentioned methods of improving heatdissipation or its removal are unnecessary.

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8.5.2 Short Circuit Ratings

Section 4.3 of IEC 947, Part 1, section 4.3.5 and 4.3.6 [36] shall apply. The rated short-timewithstand current shall pass for no less than one second. The rated short-circuit makingcapacity as defined in IEC 947, Part 1, section 4.3.6.2 shall apply.

The SWGR shall be capable of carrying continuously its rated currents at the site conditionsin all its circuits simultaneously without reducing the making, breaking, dynamic or short timethermal operating duty ratings. The following ratings shall be given careful attention by themanufacturer : -

• Symmetrical RMS making current at the first peak of the wave-form.

• Asymmetrical peak making current at the first peak of the wave-form.

• Symmetrical RMS breaking current at the quoted time.

• Asymmetrical peak breaking current at the quoted time.

• Fault clearing time of the circuit breakers, including the performance of the fastestprotective relay in the circuit breaker controls.

• The manufacturer shall, if requested by QGPC, provide oscillographic results from theType Testing of the same type of SWGR that is being offered, to substantiate the aboverequirements.

Note 8.5.2a : - The above applies particularly to incoming, bus-section andinterconnecting circuit breakers and to the bus-bar system of the SWGR.

Note 8.5.2b : - Where calculations are used the method of calculation shall be based onIEC 363 [23] or IEC 909 [35], and the results shall be given in kA(RMS)and kA(Peak) as appropriate.

The SWGR and its components shall be capable of withstanding without damage the thermaland dynamic stresses resulting from the prospective short circuit current, and without injuryto personnel. The maximum prospective short circuit current shall be as stated in the datasheets. The peak value of the rated asymmetrical withstand current shall be that given in thedata sheets. The “ Doubling Factor “ shall be taken to be no less than 1.4 when assessing thepeak value where no other data is available from which a more accurate calculation could bemade.

8.5.3 Rated diversity factor

For temperature rise tests or temperature rise calculations, a diversity factor of 1.0 shall beapplied for each switchboard tier containing only one functional unit. If a tier contains two ormore functional units then the rated diversity factor applied shall be not less than 0.9. Thisrequirement shall apply when all the functional units are assumed to be fully loaded. If any ofthe functional units in the tier are Spare Units then they shall be assumed to be 90 % fullyloaded.

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8.6 Voltage and Frequency Variations

All components shall as a minimum and unless otherwise stated in data sheets or projectdocuments have their nominal ratings determined by the QGPC’s nominal system voltages andfrequency. These components shall operate correctly, continuously and without beingoverloaded when the QGPC’s nominal system voltages deviate by plus or minus 10 % for longperiods of time. Likewise when QGPC’s nominal system frequency deviates by plus or minus5 %.

All low voltage devices that obtain their supply voltage from a) the bus bars directly, or b)from VTs connected to the main power bus bars, or c) from an external a.c. source; shalloperate correctly during a transient depression in voltage from 100% to 80%, e.g. during thedirect-on-line starting of large induction motors.

8.7 Type Test Certification

The complete SWGR shall have been TYPE TESTED by an internationally recognised testingauthority at the required operating and short circuit duty in accordance with IEC 947 [36]section 8.1.1 and other relevant IEC standards. Copies of the test certificates shall besubmitted with the tender documentation. In this respect the SWGR shall be considered as asingle complete unit in that the type tests shall be performed on bus bars, bus risers, bracing,connections, circuit breakers, current transformers etc. as a complete cubicle in the form ofconstruction that will be delivered to the site. Any de-rating of the normal operating current, orany of the various fault current duties, due to the high ambient temperatures that are usuallyexperienced at QGPC sites shall be clearly stated in the documents issued by the manufacturerto the QGPC. The default ambient temperature shall be 45 deg C if it is not specified on thedata sheets or in the project specification for the SWGR.

Test certificates for parts of the SWGR tested in isolation, e.g. a circuit breaker not rackedinto its enclosure tested in open air conditions, will not be accepted by the QGPC.

If the bus bar adapter sections are not type tested as above then the manufacturer shall providefull technical details and proposals for testing them, at the tendering stage. (These adaptersmay be required in mixed SWGR where circuit breakers and contactors are proposed).Verification, including calculations, will be required that supports and bracing at least matchthe strength of the type tested units under the same test conditions.

Certification detailed above shall include tests with insulation fully fitted to bus bars and theirconnections.

Certification detailed above shall apply to current transformers, protective relays, energy(kWh) metering equipment and electronic equipment covered by the EMI requirements of thisspecification.

See also (9.8) for bus bar ducting.

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8.8 Radio Frequency Interference Limits

Electronic devices and their associated wiring within the SWGR shall be screened to a level,which will prevent electromagnetic radiation from interfering with the proper performance ofequipment outside the SWGR

Likewise the electronic devices within the SWGR shall have an adequate level of intrinsicimmunity to external electromagnetic interference (EMI) such that they operate as intended atall times.

The immunity to EMI shall comply with IEC 255 Part 5 [19], IEC 947 section 8.4 [36] andIEC 1000 Part 4 [37], and Type Test Certificates from a recognised testing authority to verifythis shall be made available to QGPC upon request.

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9.0 Common Design and Construction Requirements

9.1 Enclosure and Component Degrees of Ingress Protection

9.1.1 The Switchgear

The required degree of ingress protection for indoor SWGR enclosures shall not be less thanIP 42 as defined in IEC 529 [30].

Partitions, shutters and inspection windows forming part of an enclosure shall provide therequired degree of ingress protection of not less than IP 30.

The casings or enclosures of all protective relays shall have a degree of ingress protection notless than IP 54.

The casings or enclosures of all panel meters shall have a degree of ingress protection not lessthan IP 52.

9.1.2 The Bus Bar Ducting

The degree of ingress protection for indoor bus bar ducting shall be IP 42 or better, and foroutdoor bus bar ducting shall be IP 55 or better.

9.2 General Features of Enclosures

The enclosure of each cubicle shall be strong enough to accept the weight of a person ofnominal weight 100-kg standing on top without causing harmful distortion.

All components that will require periodic maintenance shall be easily accessible.

The ‘back-to-back’ layout of the low voltage SWBDs should be avoided, rear access forpower and control cables is preferred.

Rear access cubicles shall have ‘lift-off’ type hinged doors.

The incoming cubicles shall be located in the centre of the SWBD.

Any special requirements shall be described by QGPC within the project documentation anddata sheets.

Doors and covers to high power compartments, which may be opened without the use of tools,shall be provided with mechanical interlocking and padlocking facilities.

Withdrawable equipment shall be equipped with a mechanical ‘stop’ to limit the horizontaltravel distance.

SWGR assemblies shall be a sheet steel construction at least 1.5 mm thick and shall beextensible at both ends without cutting, drilling or welding any part of the equipment. It shallbe possible to erect extension units without isolating the SWGR until it is required to connectthe bus bars.

The maximum height shall be two metres. No meter panel or relay panel shall extend above aheight of 1.6 metres, nor be located below 200 milli-metres.

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Alphanumeric notation of conductors and terminals shall generally be in accordance with IEC445 [27].

Outgoing unit sections shall be arranged for bottom cable entry unless specified otherwise onthe data sheets.

Note 9.2a : - Cabling facilities should be discussed in detail at the tendering stage to ensurethat they are suitable for the maximum size of cables to be expected and thenumber of control cables. The manufacturer shall provide a list of maximumcable sizes for each unit in the tender documentation. Alternativearrangements for glanding the armoured cables at the bottom of the enclosureor in the substation basement should be considered, e.g. for large switchboardinterconnectors. See also (9.11) ‘Connection of QGPC’s cables’. The cableentry direction should be indicated on the data sheets or project drawings.

Note 9.2b : - The cable entry direction for onshore plants will usually be from below. Thecable entry direction for offshore plants will usually be from above and in amodular type of switch-room.

9.3 Safety

The SWGR shall be designed to ensure maximum safety during all operating conditions,regular inspection, testing, maintenance and installation. Comprehensive interlocking andsafety barrier systems shall be provided in each cubicle of the assembly.

Alarms shall be provided and located so that the switchboard operator shall be in no doubt atany time as to which device has caused a power circuit breaker or contactor to trip.

The form of separation shall be Form 4 Type 1 or 4, which shall be stated on the data sheets.

The design and construction of the enclosure shall be such as to reduce the passage of flame,vapour or gases between compartments. This requirement applies to wiring ducts, riserchambers etc.

An arc propagation barrier shall be provided in the bus-section circuit breaker cubicle.

9.3.1 Test Reports for Internal Arcing Faults

Test reports shall be submitted by the manufacturer in his tender documentation to confirmthe SWBD capability of containing internal arcing faults in accordance with IEC 298 [21]Annex AA, Type A, requirements, i.e. SWGR with accessibility restricted to authorisedpersonnel only. Note, although [21] applies to HV switchgear QGPC requires that the detailsin the Annex AA shall also apply to LV switchgear. The measures to be provided by themanufacture to limit the consequences of internal faults shall be in the inherent design strengthof the enclosure together with the following alternative examples from the Annex AA asfollows : -

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• Rapid fault clearance times initiated by detectors sensitive to light, pressure or heat.

or

• Application of suitable fuses in combination with switching devices to limit the let-through current and fault duration.

or

• Pressure relief devices.

The sub-section AA.4.5 of the Annex shall apply.

The sub-section AA.6 criteria No. 1 and No. 2 of the Annex shall apply.

The test reports shall confirm all of the above requirements, and be based on arcing faultsupstream of short circuit interrupting devices unless it can be demonstrated that such enclosedareas can be deemed as ‘fault-free zones’ by the use of all insulated components.

9.3.2 Safety Shutters

Safety shutters shall automatically cover all busbar contacts whenever the withdrawable partsare isolated or withdrawn.

Movement of the withdrawable part shall individually operate shutters. The opening andclosing of the shutters shall be by a positive mechanical drive.

Shutters shall be arranged so that only those required for a particular operation are open.

Facilities for shutters to be padlocked ‘closed’ shall be provided.

Means shall be provided for opening each set of shutters to facilitate testing. This means shallnot prevent restoration of the automatic features of the shutters when the withdrawable part isreplaced into its original position.

Shutters shall be brightly coloured red for the bus bar side, and yellow for the circuit side, andeach one shall be labelled with black coloured letters stating ‘DANGER - - - VOLTS’.

All covers that provide access to the main bus bars shall have a warning label attached ontheir outside surface, see (9.20).

9.3.3 Power Switches and Isolators

Power switches and isolators shall comply with IEC 947 [36].

9.3.4 Remote Operation of Switching Devices

QGPC shall state clearly in the project documentation whether or not remote control isrequired. If it is required then the following shall apply.

The SWGR should be designed for local control, at its cubicles; and remote control from aseparate panel or control station, control room or elsewhere. A selector switch should beprovided at the front panel of each cubicle to enable each power-switching device to beoperated as required at either location as selected. This requirement shall also be compatiblewith the safety and interlocking subjects described in this specification.

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The requirements for local and remote control shall be fully described in the QGPC projectdrawings, data sheets and documentation.

9.3.5 Modes of Operation

The power switching devices shall be able to be placed in their ‘disconnected’ (‘withdrawn’),‘isolated’, ‘test’, and ‘in service’ positions in such a manner that their truck will bemechanically prevented from moving once placed in the desired position, see also (10) and(11).

If a separate ‘test’ position is not available for constructional reasons, then a testing system asdescribed in (12.13) shall be provided.

9.4 Interrupting Medium of Circuit Breakers and Contactors

The interrupting medium of circuit breakers and power contactors shall be air.

9.5 Interchangeability

Electrically identical components shall be of one type and from the same manufacturer.

Circuit breakers of the same rating shall be interchangeable.

Power contactors of the same rating shall be interchangeable.

A mechanical mismatching system shall be provided to prevent the entry of units, which arenot identical.

9.6 Spare Cubicles and Extendibility

Where spare cubicles and trays are specified on the data sheets or single-line diagrams theyshall be fully equipped, such that future additional equipment can be installed without shuttingdown the SWGR.

If spare outgoing cubicles and trays are not specified on the data sheets or single-line diagramsthen at least two of each type and rating shall be provided in each section of the main busbars. These spares shall be located at the bottom of the vertical tiers, if possible.

The cubicles and trays shall be fitted with CTs, VTs, relays, etc. in accordance with thefunction of the circuit required, e.g. motor starter, plain feeder, as stated on the data sheets orsingle line diagrams. Current transformer ratios and ammeter scale ranges shall be as statedon the data sheets or single line diagrams.

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9.7 Bus Bars

Bus bars shall include both horizontal and vertical components and shall have the followingfeatures: -

• Bus bars shall be located in a separate compartment or chamber, or as required by theForm 4 design, see (9.3).

• Electrolytically refined hard-drawn high conductivity copper shall be used, which shall befully rated, braced and supported to withstand all dynamic and thermal forces, anddielectric stresses. Aluminium shall not be used for any current carrying components.High tensile steel bolts shall be used at all bus bar connections, and these shall be securedagainst loosening. The horizontal bus bars shall be fully rated. The horizontal bus bars ineach tier shall have the same rating.

• If not otherwise specified in the requisition, the assembly shall be laid out for a TN-Spower system, i.e. with separate neutral and phase bus bars throughout the system,including the droppers (also called risers). The main bus bars shall be rated for thenominal current over the entire length of the assembly, and shall not be rated lower thanthe incoming and sectionalising circuit breakers. The main bus bars shall be easilyextensible at both ends.

• A 4-wire phase and neutral system of bus bars and droppers (also called risers) shall beprovided. The droppers in each tier shall include the neutral, and all outgoing cubiclesand trays shall be capable of easy connection to the neutral, whether or not theirparticular circuit happens to be intended only for 3-wire operation. The vertical droppersin each tier shall have the same rating.

• The current rating of neutral bus bars shall be no less than 50% of the correspondingphase bus bars. The smallest cross-sectional area of a neutral bus bar shall be 16 squaremilli-metres.

• Connections and circuit wiring to load circuit fuses shall have a continuous current ratingat least equal to that of the largest fuse link that can be fitted.

• All power connections shall be tinned.

• The phase colouring and rotation required shall be as shown in Table 9.7.A.

• An air-insulated bus bar system is not acceptable.

• All LV bus bars and connections shall be fully insulated with flame retardant materials,which comply with IEC 332 [22]. Insulating caps shall be provided for all connections,which can be removed for inspection and maintenance. Insulation materials shallwithstand without damage the effects of carrying the rated short time withstand current ofthe SWGR.

• Clearance and creepage distances shall comply with IEC 664 [31] and IEC 664A [31]category IV.

• A minimum of connections and the location of measuring devices such as CTs (and VTs)shall be made to the bus bars or to the copper-work between the bus bars and the powerswitching devices. CTs shall be located on the ‘cable’ side of all the power switchingdevices, except for bus-section switching devices. If CTs are required for bus barprotection or measurement in the bus-section switching devices, they shall be specified inthe project documents, and they shall be carefully mounted in a bus bar chamberdesigned for the purpose.

Revision A

Table 9.7.APhase Rotation and Colour Coding of Bus bars

Origin Identification

QGPC Preference L1 L2 L3

United Kingdom Red Yellow Blue

European U V W

R S T

United States of America A B C1 2 3

9.7.1 Transformer Incomer Neutral Earthing

The neutral circuit of each transformer incomer shall be connected to the earth bus bar bybolted links such that the connection is physically located on the bus bar side of the neutralisolating facility. This facility shall be either a bolted link or one of the poles of a 4-polecircuit breaker. A 4-pole circuit breaker shall be the normally preferred choice if such a CB isa standard item of the manufacturer’s range of equipment. All earth links shall be labelled‘neutral earthing link’. Provision shall be made for the installation of CTs on each incomingneutral connection, both before and after the point where it is earthed, and on the connectionsto the earth bus bar.

Alternative configurations, in which the connection point to earth is different from that above,may be offered to QGPC for discussion and approval in writing.

9.7.2 Generator Incomer Neutral Earthing

The neutral circuit of each generator incomer shall be connected to the earth bus bar by boltedlinks such that the connection is physically located on the bus bar side of the neutral isolatingfacility, in the same manner as described in (9.7.1).

9.8 Bus bar Ducting

Bus bar ducting for connecting the power transformers to the SWGR or for connectingbetween two enclosures of SWGR, instead of cables, shall be provided by the manufacturerwhere specified on the data sheets or shown in one-line (single-line) diagrams. Themanufacturer shall be responsible for coordinating the design and delivery of the bus barducting, unless agreed otherwise in writing with QGPC. The Scope of Supply shall include,adapters for connecting into the transformer terminal boxes, adapters for connecting into theSWGR, gasgets, supports, right-angle or angled sections, wall penetration sections, flexiblecopper terminal connections, sun shades, special tools and all documents for erection andtesting. The bus bar ducting shall be from the manufacturer’s standard product range andshall be Type Tested for fault current duty, in a similar manner to that of the SWGR, see(8.7).

No proto-type designs shall be offered or used.

Revision A

The normal current and fault current ratings of the bus bar ducting shall be at least the sameas the SWGR main bus bars, and shall be certified accordingly as required in (8.7) above. Ifany part of the bus bar ducting is to be installed outdoors then the whole of the bus barducting system shall be rated for the outdoor ambient temperatures. The manufacturer shallstate what derating factors will be used from a standard temperature of 20 deg C.

Unless otherwise stated the bus bar ducting shall be fabricated from sheet steel, dust protectedand weatherproof, and shall include a weatherproof seal for the entry through the switch-roomwall.

9.9 Earthing Facilities for the Enclosure

Earthing facilities shall comply with IEC 439 [26] and the following : -

• An internal hard-drawn high conductivity copper earth bus bar shall be provided alongthe full length of the SWGR with joints between each transportation unit. At each end ofthe SWGR and under each incoming circuit breaker compartment the earth bus bar shallhave an M12 brass terminal for connection of an external earth cable. The earth bus barshall be located near the rear bottom of the assembly.

• A vertical earthing bus bar shall be provided in each tier to service each tray orcompartment, and it shall be bolted at one of its ends to the horizontal earthing bus bar.

• The bus bar shall be capable of carrying the maximum ground fault current withoutdamage to itself or its supports for the time allowed by the slowest responding relay, orone second which ever is the longest time. The ground fault current shall be at least equalto the maximum three-phase short circuit current that can occur when all the incomer andbus-section CBs are closed.

• Earth bus bars shall be sheathed with green, or green with yellow, insulating materialalong its entire length, except at connection points for internal and external cables orstraps.

• Bonding connections shall be provided for covers and doors and shall be arranged toavoid damage during their opening and closing.

9.10 Interface Panels

The SWGR control circuits will be required to interface with external systems such as LoadManagement Systems, process controllers, fire and gas systems, emergency shut-downsystems, SCADA or DCS. Such circuits shall be marshalled into their corresponding interfacepanel so that the amount of external cabling is minimised.

The SWGR shall have a dedicated compartment in each bus-section for making theseinterfaces possible in the easiest manner possible. The relevant signals may be hard-wiredindividually or be combined in a computer based network arrangement. The manufacturershall include in these interface panels all the necessary relays, transducers, networkingmodules, terminal blocks, networking plugs and sockets, memory hardware, adapters, digitalconverters and the like.

These panels shall have at least 20 % spare capacity for future use.

These interface panels shall not interfere with the extensibility of the switchboard at itsextreme ends.

Revision A

9.11 Connection of the QGPC’s Cables.

QGPC will provide full details of the type and construction of the external cables, which willbe connected to the SWGR.

Provision for QGPC’s cables shall be made as follows : -

• Separate terminal boxes shall be provided at the rear of each SWGR unit for the mainand auxiliary circuit cables. Each box shall have a brass stud for terminating the earthconductor of the external cable.

• Plenty of space and the necessary system of connections shall be provided for situationswhere more than one core of power cables need to be terminated on one power terminalof the SWGR.

• The manufacturer shall not provide power cable lugs (which will be of the crimped type).However, the manufacturer shall provide the necessary number and type of bolts,washers, nuts etc., which match his copper-work.

• Sufficient space for access and termination of cables shall be allowed, giving particularattention to bending radii of cables used in each application, e.g. switchboard inter-connectors and main generators will often require more than two cable cores per phase.

• Provision shall be made for the support of external cables at intervals not exceeding 500mm between the cable entry and the top or bottom of the SWGR depending on thedirection of entry, see Note 9.2b.

• Main and auxiliary circuit cables within an enclosure shall be segregated.

• Terminals for the QGPC’s connections shall be clearly marked with the terminal numbersas shown in the manufacturer’s wiring diagrams.

• It shall not be necessary to dismantle the earthing bus bars in order to terminate power orcontrol cables.

9.12 Gland Plates

Gland plates shall be provided as follows : -

• Manufactured in brass metal if single core power cables are to be used and shall bedelivered un-drilled.

• Manufactured in steel metal, plated with cadmium or galvanised, if three or four corepower cables are to be used and shall be delivered un-drilled.

• To take account of the size of the power and control cables and the termination positions,especially when several power cables are required for a switching device. Adequateclearance and manoeuvring distance for the cables shall be provided.

• To include an earth stud which shall have an earth cable or strap connection to the mainearth bar.

Revision A

9.13 Basic Interlocking

The interlocking arrangements shall be at least those stated in IEC 947 [36], Part 1, section7.1.6. Mandatory interlocks shall be mechanical devices. Where possible, interlocking withina cubicle shall be made by mechanical devices.

The manufacturer shall submit all the necessary information on the character and function ofthe interlocks.

If earthing switches are to be used then they shall be interlocked with their associateddisconnecting devices.

The following provisions are mandatory for main circuit breakers : -

• The withdrawal or engagement of a circuit breaker, switch or contactor shall beimpossible unless it is in the ‘open’ position.

• The operation of a circuit breaker, switch or contactor shall be impossible unless it is inthe ‘service’, ‘disconnected’, ‘removed’, ‘test’ or ‘earthing’ position.

• It shall be impossible to close the circuit breaker, switch or contactor in the ‘service’position unless a) it is connected to the auxiliary circuit, or b) it is designed to ‘open’automatically without the use of an auxiliary circuit.

Interlocks shall comply with the following : -

• Any interlock capable of being defeated without the use of special tools for a particularsafe purpose shall be provided with a padlocking facility.

• The door of the compartment shall be prevented from being opened unless the unit isisolated.

• Withdrawable units shall be prevented from being withdrawn or from being replacedwithout being isolated.

• The test facility within starters and contactor outgoing feeders shall prevent door closureor replacement of a withdrawn unit whilst the test supply is connected.

• All isolating devices shall be padlockable only in their ‘off’ position.

• See also Appendix B for a description of schemes for the momentary paralleling of dualfeeders (also called ‘2-out-of-3’ schemes). The incomers and bus-section CBs shall bearranged in a Secondary Selective scheme as described in ES.2.14.0060 [51] if stated inthe data sheets or the project documentation. Even if this requirement is not needed, theincoming CB(s) shall be interlocked by electrical circuits to ensure two-way inter-tripping is achieved with the sending end CB(s), via appropriate master trip/inter-triprelays mounted in the SWBD and wired to terminal blocks.

• These schemes shall only be provided if specified in the requisition documents e.g. datasheets, one-line diagrams, interlocking diagrams.

• Disconnectors and isolators shall be interlocked to prevent their operation unless theassociated circuit-switching device is ‘open’.

• Where key operated mechanical interlocks are required they shall be described in theproject documentation e.g. the data sheets.

• See also (9.3).

Revision A

9.14 Internal Wiring

Internal wiring shall comply with the following : -

• Type : - BK to BS 6231 [43] (or IEC equivalent standard ).Fire performance : - Flame retardant to IEC 332 – 1 [22].Insulating material : - PVC moisture resistant.Insulation grade : - 600VConductors : - Tinned stranded copper.

Core strandingto suit current : - 1.5 sq mm, 30 strands at 0.25 mm diameter.

2.5 sq mm, 50 strands at 0.25 mm diameter.MinimumCore size usage : - 1.5 sq mm for control wiring.

2.5 sq mm for a.c. and d.c. power wiring.

• Multi-strand conductor ends shall be fitted with a crimped terminal device with aninsulating straight shank.

• Where the current transformer secondary circuits have a rated current of 5 amps the coresize of the internal wiring and external field cables may need to be 4.0 sq mm.

All wiring shall be fitted with interlocking numbered identification ferrules in line with themanufacturer’s drawings. Ferrules shall not be of the split or clip-on type. Ferrules shall befitted at both ends of the wire unless the wire is individually routed and is less than 100 mmlong. Ferrules shall be indelibly marked with a number or letter and the background colourmay be coded to the number system. It shall be necessary to disconnect the termination inorder to remove the ferrules. Paper ferrules are not acceptable.

Wiring across door hinges shall be protected against mechanical damage, e.g. by the use offlexible conduits. This wiring shall be rated to match the largest fuse in the control circuits.

Wiring for circuits, in each SWGR unit, which are connected to bus-wired power suppliesshall be protected by fuses or MCBs for. The incoming supply for all these circuits shall beprotected by a fuse or MCB, which shall selectively grade with all the sub-circuit devices. Thevarious types of incoming supply, e.g. closing, tripping, shall preferably enter the SWGR ateach bus-section tier in an appropriate LV termination compartment, e.g. the interface panel.

Wiring between compartments shall be carried within a duct and shall be accessible withoutthe need for de-energizing any circuits. Sufficient space shall be left in ducts and trunking forat least 10 % of the wires to be installed after delivery to the QGPC site. Where theapplication of microprocessor based systems would be supported by a different approach tointernal wiring and marking, the proposed approach shall be agreed in writing by QGPC.

Inter-compartment wiring shall not use the main bus bar chamber or compartment, it shallhave dedicated channels or ducting for its purpose.

Revision A

Where inter-compartment wiring crosses a transportation slit between tiers, then terminalswith identical numbering shall be provided on both sides of the split together with a shortnumbered connecting wire to connect each pair of terminals, following installation of thecomplete assembly. (This approach is required to minimise the amount of site-run wiringduring installation, especially for offshore projects). The manufacturer should discussalternative approaches with QGPC at the tendering stage.

All wiring shall be traceable from the manufacturer’s drawings.

9.15 Internal Wiring Terminals

Screw clamp (or stud) type shall be provided. Pressure plates shall be incorporated such thatneither screws or nuts bear directly on a wire. Wiring connections relying only on solder arenot acceptable, (except for internal circuits of electronic equipment such as protective relays).

For internal wiring, not more than two wires shall be attached under any terminal screw orpost.

Terminals for different a.c. voltages shall be separated from each other by a barrier andcompletely segregated from d.c. circuits.

All terminals on door mounted equipment shall be fully shrouded with insulation material.

A number in line with the manufacturer’s wiring diagram shall identify every terminal.

Wiring terminal blocks shall be arranged and positioned to afford easy access for carrying outexternal cabling, testing, inspection and maintenance. For current and voltage transformersecondary circuits, terminals with facilities for measuring, secondary injection testing,isolating or short-circuiting, as necessary shall be provided. Terminals shall be Klippon SAKtype or equivalent and made of polyamide material or better.

A minimum of 20 % of each type of terminals shall be provided on each terminal block orstrip in each compartment or cubicle.

Where spare auxiliary contacts are provided, e.g. CB mechanisms, truck switches, alarmdevices, they shall all be wired to the relevant terminal blocks, numbered and identified.

For wiring to outgoing terminal blocks, a separate terminal shall be provided for eachconductor. When more than one outgoing conductor needs to be connected together, therequisite number of terminals shall be interconnected by means of permanent solid links.

Terminal blocks with shrouds shall be grouped by operating voltage and each group shall belabeled ‘ DANGER . . . . . VOLTS’.

All terminals shall be traceable from the manufacturer’s drawings.

Revision A

9.16 Floor Frames

The SWGR shall be mounted and bolted on to a purpose-built floor frame or frames if theSWGR is long or is split into sections. The manufacturer shall provide the floor frames, whichwill enable the SWGR units to be easily aligned during erection on site. The frame shallinclude all jacking bolts, shims, packing pieces, nuts, bolts, washers etc., that are necessaryduring the erection at site. The frame shall be made of substantial ‘I’ or channel section steelbeams. The top surface of the frame will be flush with the switch-room floor, and in no wayshould the use of such a frame hinder the mobility of the withdrawable units.

9.17 Padlocking facilities

The padlocking facilities shall be at least the following : -

• All shutters in their ‘closed’ position.

• All ‘local and remote’ selector switches in either position.

• All racking devices in the ‘disconnected’, ‘service’, or ‘earth’ position.

• Compartment doors shall be lockable with an integral lock.

• All isolators in the ‘off’ position only.

• All circuit breakers and contactors in their ‘off’ and ‘disconnected’(or ‘withdrawn’)positions.

• It shall not be possible to padlock any switching device in its closed position, except forswitches used for earthing.

Note 9.17a : - Padlocks themselves will be provided by QGPC. They should have a haspdiameter of no less than 6 mm. Barrel type lock are not acceptable.

9.18 Manual Operation of Equipment

Equipment supplied in this section may be included in (9.22) and (9.23).

Manual operation of the equipment will be an abnormal but occasionally necessary operation,e.g. when there is a loss of a control supply to a unit.

The following equipment shall be provided : -

• One set of equipment for closing each type of incoming and bus-section CB by hand.

• One set of test jumpers for allowing the control circuits to be tested when a unit is inits ‘Test’ position (as part of the requirement of (12.13)).

9.19 Anti-Condensation Heaters

The details of the humidity and purpose of the heaters is described in (6).

Anti-condensation heaters shall be provided in each tier and each cubicle. One or moresuitably rated anti-condensation heaters shall be required in each enclosed compartment ofeach vertical tier, e.g. metering, instrument, distribution compartments. The heaters shall bethermostatically controlled.

Revision A

An anti-condensation heater control system shall be provided in each equipment, consisting ofthe following : -

i) A differential thermostat shall be used to control the heater so that the equipmentinterior temperature is maintained at 4 deg C to 5.5 deg C above the air temperature,when the HVAC is operating normally.

ii) The differential thermostat shall be cut-off by one or more automatic devices set fora maximum equipment interior temperature of 35 deg C. The devices shall reset to32 deg C. Devices shall be located in enough typically loaded sections to preventlocal overheating.

The heater supply for each busbar section shall be taken from an external source. It shall beprotected by an earth leakage circuit breaker (ELCB) mounted in each bus bar section, e.g.the interface panel. The ELCB shall have a sensitivity of 30 mA. A switch mounted on thefront of the section cubicle shall enable all the heaters in the section to be isolated, and a redlamp shall indicate that the supply is energised.

A local terminal block shall feed all the heaters in the section and shall have a label clearlyindication the function. The local terminal blocks will be used during the storage of theSWGR at site, where a temporary supply will be made available.

A nameplate shall be mounted on the front of each motor starter cubicle which supplies amotor fitted with a heater. The nameplate shall be engraved with white letters on a redbackground and shall read: -

___________________________________________________WARNING

AUXILIARY CONTACTS CONTROLLING MOTORANTI-CONDENSATION HEATER MAY BE

ENERGISED FROM AN EXTERNAL SOURCE___________________________________________________

9.20 Labeling

The language for all labels shall be English unless specified otherwise by QGPC.

9.20.1 Labeling of components

Labels shall be provided as follows:-

• Each compartment shall be identified with a label at the front and rear on the fixed partof the assembly, marked with the cubicle reference and service description as specified inthe data sheets.

• Withdrawable parts shall be provided with circuit identification labels.

• A common switchboard nameplate shall be provided and located on the front of the bus-section circuit-breaker tier (or another designated tier) detailing the order number andmanufacturer’s contract reference, date of manufacture, making and breaking capacityrating.

Revision A

• A large label giving QGPC’s bus-section tag number, tag name and voltage shall belocated on the front of the SWGR at the corresponding section of the switchboard.

• Labels shall be provided with unique code references corresponding to themanufacturer’s schematic diagrams for the following : -

i) Each control switch.

ii) Each indicating lamp.

iii) Each fuse and link.

iv) Selector switch positions.

v) Each instrument.

vi) Each relay.

• Spare compartments and trays shall be labelled to indicate the highest normal currentrating that can be used in the future.

• Labels shall be engraved, screwed and not fixed by adhesive. Their colouring shall be:-

i) All except below, black lettering on a white background.

ii) Danger labels, black lettering on a yellow background.

iii) ‘Stop’ warning labels, red lettering on a white background.

• Terminal label markings shall comply with IEC 445 [27].

• Lettering shall be at least 20 mm high on all external labels.

• A durable synoptic one-line (single-line) diagram shall clearly show the function of eachcubicle.

• Where special or unusual operations are required at cubicles then an instruction labelshall be fitted close to the appropriate mechanism.

9.20.2 General equipment nameplate

The following information shall be given on the general equipment nameplate:-

• Manufacturer‘s name or trademark.

• Manufacturer‘s serial and reference number of the product.

• Type designation.

• Purchase’s name.

• Purchase order number and date.

• Year of manufacture.

• Rated voltage.

• Rated Frequency

• Rated current of the bus-bar system at 45 deg C.

• Rated voltage of the auxiliary circuits (if applicable).

• Rated peak and short time withstand current and withstand time.

Revision A

• Degree of protection to IEC 529 [30].9.21 Painting

Painting shall be the manufacturer’s standard for tropical, harsh and marine conditions, andshall be described in his tender documents. QGPC shall advise the required colour in the datasheets. (See BS 4800 [41] for standard colours).

9.22 Handling Trucks

The manufacturer shall provide a minimum of one handling truck for each SWBD as part ofthe Scope of Supply, if such a truck is normally required for the SWGR.

9.23 Special tools and Lifting Facilities

The manufacturer shall offer a minimum of one set of special tools for each complete SWBD,(since SWBDs may not necessarily be located in the same switch-room or site). These toolsshould be part of the Scope of Supply, if they are normally required for the SWGR. QGPCwill confirm the need for these tools at the tendering stage of the order.

The manufacturer shall offer the method and equipment required for the safe lifting of thetransportable assemblies. These shall be discussed and agreed at the tendering stage, e.g. eyebolts, slings, spreader beams. Detailed instructions for the lifting of the SWGR shall beincluded in the Operating and Maintenance Instructions.

Revision A

10.0 Circuit Breakers

Circuit breakers shall comply with IEC 947 Parts 1 and 2 [36], utilisation category B suitablefor uninterrupted duty.

The performance of the circuit breakers described in IEC 947 Parts 1 and 2 [36] shall beverified when they are installed within the enclosure or assembly for the exact configurationbeing offered and purchased, see also (8.5) and (8.7).

All CBs shall be withdrawable. Their circuit requirements shall be stated in the data sheets.

All CBs shall be capable of being tripped mechanically in the event of loss of electricity.

For the application of 3 or 4 pole CBs, see (9.7.1) and (9.7.2).

Circuit breakers shall be used for motor starters where the kW rating of the motor is too highfor a fuse-contactor or MCCB-contactor combination to be used in a fully proven and testedmanner.

See also Appendix A.

10.1 Functional Requirements

• Each CB shall be connected to the bus bars and its feeder circuits through plug andsocket type isolating devices.

• The isolating devices shall be self-aligning.

• See also (9.13) and (12.13).

10.1.1 Operating mechanisms

Operating mechanisms shall have the following facilities : -

• Shall incorporate an anti-pumping device.

• The spring charging mechanism shall function automatically and a soon as the CB hasclosed. A manual spring charging facility shall also be provided.

• A local manual trip fitted with a fully guarded button.

• All CBs with automatic close operations shall have the manual close facility on thecubicle pad-lockable in the non-operative position. The mechanical trip mechanism shallnot be inhibited when the close facility is locked OFF.

• If the standard equipment has a local manual close facility, then this shall be disabled onall CBs having synchronising check relays and on any other CBs, which areinterchangeable.

• Directly driven mechanical indication of the CB position visible from the front of thecubicle.

• For incomers, bus-section and switchboard inter-connectors, which have their operatingmechanisms fitted with d.c. shunt-trip circuits (i.e. energise to trip), they shall also befitted with trip circuit supervision. This supervision shall not alarm when the CB isisolated.

Revision A

• Operating mechanisms fitted with electric closing circuits shall have interlocks so thatclosing cannot be initiated when a trip condition exists e.g. lockout relay operated and notreset.

• Close and trip circuits shall be protected by fuses or MCBs, and arranged so that it is notpossible for the closing mechanism to operate if the trip fuse or MCB is open circuit.The protection shall be co-ordinated such that under all conditions, the fuse or MCBnearest the fault operates first without damaging or reducing the life or performance ofother fuses or MCBs.

• A ‘on’ or ‘running’ indicating lamp shall be fitted on the front of each cubicle, see (12.3).

• A ‘off’ or ‘stopped’ indicating lamp shall be fitted on the front of each cubicle, see(12.3).

10.2 Circuit Earthing

10.2.1 Incoming Circuit Earthing

It is necessary to have earthing switches or earthing devices for the incoming circuits. If theyare specified in the project documentation then they should be 3-pole types and shall be fittedon the ‘cable’ side of the circuits, and the manufacturer shall describe these facilities in histender documentation. The earthing switches or earthing devices shall have a short-circuitcapability at least equal to that of their incoming circuit breakers.

10.2.2 Outgoing Circuit Earthing

It is not generally necessary to have earthing switches or earthing devices for the outgoingcircuits. If they are specified in the project documentation then they should be 3-pole types andshall be fitted on the ‘cable’ side of the circuits, and the manufacturer shall describe thesefacilities in his tender documentation. The earthing switches or earthing devices shall have ashort-circuit capability at least equal to that of their outgoing switching devices.

Revision A

11.0 Contactor Motor Starters and Contactor Feeders

DOL motor starters shall comply with IEC 947, Part 4 [36].

The requirements for all special starters, i.e. other than DOL starters, shall be described indetail by QGPC in the project documentation.

Auto-transformer motor starters shall comply with IEC 947, Part 4 [36], and be suitable forClass 12 intermittent operating duty i.e. 12 starts per hour. They shall have tappings for 50%,65% and 80% of the nominal line voltage. They shall selected assuming that the motors willbe designed to BS 4999, Part 112 [42], Design D.

Star-delta motor starters shall comply with IEC 947, Part 4 [36].

Rheostatic motor starters shall comply with IEC 947, Part 4 [36].

Contactors shall comply with IEC 947 [36].

All motor starters and feeder contactors shall be withdrawable.

Each direct-on-line starter circuit and contactor feeder circuit shall be provided with thefollowing equipment : -

• Isolation.

The isolation shall be mechanically and electrically interlocked with the contactor toprevent on-load operation.

• Main fuses or MCCBs.

Either of these shall be used to protect the contactor against short circuit damage, see(11.1).

• Contactor.

A 3-pole power contactor shall be provided for both 3-wire and 4-wire consumer circuits.A neutral link shall be provided for 4-wire consumer circuit.

• Control.

Individual control supplies shall be provided for each motor starter and contactor feeder.

• Encapsulated control transformer is preferred for each circuit, with one primary fuse andneutral link, and with one secondary fuse and an earthed link. The primary fuse andneutral link shall be connected to the circuit side of the main isolating device.

• The control circuit auxiliary power transformer shall be suitably over-rated above theconsumption of the LV contactor coil and other devices in the control circuit.

• A fuse and a neutral link shall connect phase-to-neutral control supplies, if a controltransformer system is not available.

• Earthing connections of auxiliary supplies and CTs shall be removable by means of alink for testing.

• Auxiliary switches. See (12.12).

Revision A

• Protective relay equipment as listed in the data sheets. The equipment listed in AppendixA shall be the minimum required. Extra equipment required shall be shown on the projectdata sheets.

• All contactors shall trip in the event of loss of electricity at the main bus bars.

• All motor contactors shall close upon restoration of the electricity at the main bus bars ifa ‘close’ signal exists.

• If stated in the data sheets or the project documentation all motor contactors shall closeas required in a ‘secondary selective’ scheme described in ES.2.14.0060 [51] and in there-acceleration scheme described in Appendix L of ES.2.03.0001 [50].

11.1 All Contactors

See Appendix A.

• Shall be anti-pumping in operation.

• Contactors shall comply with IEC 947, Part 4 [36], and shall have an uninterrupted dutyand a intermittent duty of Class 30.

• The coordination between starters and contactor feeders and the associated short circuitprotective devices shall comply with IEC 947, Part 2 [36] as Type 2. Wheninstantaneous earth fault protection is specified and Type 2 cannot be achieved, a timedelay may only be incorporated with the approval in writing by QGPC. Themanufacturer shall provide test evidence at the tendering stage to verify that thespecified coordination has been achieved.

• Contactors shall be electrically held. If they are to be mechanically latched then this shallbe stated on the data sheets, and shown on the single-line diagrams. The mechanismsshall be trip free in their design. Mechanically latched contactors shall incorporate anelectrical trip coil and a manual release. The manual release shall be guarded to preventinadvertent operation.

• Earthing connections of auxiliary supplies and CTs shall be removable for testing.

• A ‘on’ or ‘running’ indicating lamp shall be fitted on the front of each cubicle, see (12.3).

• A ‘off’ or ‘stopped’ indicating lamp shall be fitted on the front of each cubicle, see(12.3).

11.2 Additional Requirements for Motor Starters

See Appendix A.

Each direct-on-line starter circuit shall be provided with the following additionalequipment : -

• Motor starters shall be rated for both uninterrupted duty and intermittent duty Class 0.3and have a utilization category AC-3 according to IEC 947, Part 4 [36].

• Current transformers for remote ammeters shall be fitted only if specified on the datasheets.

Revision A

11.3 Additional Requirements for Feeder Contactors.

See Appendix A.

Each plain feeder circuit shall be provided with the following additionalequipment : -

• Contactor feeders, other than for motors, shall be rated for both uninterrupted duty andintermittent duty Class 0.1 and have a utilisation category AC-3 according to IEC 947,Part 4 [36].

• ‘Close’ push button on the front of the cubicle.

• ‘Open’ push button on the front of the cubicle.

11.4 Manually Switched Feeders

Manually switched feeders shall be of the swing-out or fixed panel type, unless the use of awithdrawable type is stated on the project data sheets or in the project documentation.

A manually operated mechanism shall be provided with a handle or push buttons on the frontpanel.

11.5 Isolating Devices or Disconnectors

Isolating devices shall consist of a MCCB, disconnector-fuse combination or a fuse-disconnect.

Disconnector-fuse combination or a fuse-disconnect shall comply with IEC 947, Part 3 [36],for uninterrupted duty, and AC-23B utilisation category.

The rated fused short circuit current of a disconnector-fuse combination or a fuse-disconnectshall be at least equal to the value specified in the data sheets.

The mechanism shall be of the independent manual type.

All external circuits not deriving their supply from the unit shall be connected via auxiliarycontacts on the isolator.

Revision A

12.0 Components

All components which need to be mounted on the front face of the SWGR shall be flushmounted, e.g. ammeters, voltmeters, ELCBs, relays, push buttons. If the manufacturer can notcomply with this requirement then he shall explain this in his tender documentation. Switches,MCCBs and MCBs of the ‘on’ and ‘off’ toggle operated type shall be oriented with the togglemoveable in the vertical plane.

All current (and voltage) transformers shall have labels attached, which shall detail theirratings in accordance with IEC 185 [15] and IEC 186 [16] respectively.

12.1 Electrical Protective Relays

See Appendix A, and (9.1) for ingress protection.

Electrical protective relays shall comply with the following : -

• IEC 255 [19] or other national standard approved by the QGPC. Unless otherwise statedall relays shall be the electronic type capable of communicating with SCADA and DCSsystems through network topology (referred to herein as ‘intelligent relays’). Themanufacturer shall describe in detail at the tender stage all the relays he proposes to useand the network communication details e.g. digital software language, protocol, hard-wire or optical medium, speed of transmission, hierarchy and management of informationexchange. The software for such protective relays shall be very ‘user friendly’, menudriven, and capable of being used by an operator having little experience in softwareprogramming.

• Protective relays shall be designed to withstand the output current of CTs for at least thespecified withstand time of the SWGR, see (8.5.2).

• Any single protective relay unit may contain various relaying functions in a logicalcombination, but each function shall have its own alarm and trip contacts wired toterminals. The manufacturer shall provide comprehensive brochures of these combinedrelays in his tender documentation.

• Tripping circuits and contacts shall be volt-free and separate from other circuits withinthe relay.

• The relays shall be flush-mounted and fitted on the front of the cubicle within easy reachfor the operator to reset them. They shall not be mounted near the floor. Hand resettingshall be from the outside the relay case.

• For the purposes of testing, draw-out relays shall be withdrawable with all circuitsenergised without open-circuiting current transformer secondary windings or causing theprotective system to operate. Test blocks shall be provided to facilitate secondary currentor voltage injection testing. Test equipment shall be plugged into the relay or its base. Iftest blocks are not available as standard items then the manufacturer shall describe in histender documentation an alternative method of testing each type of relay.

• Protective relays shall be located adjacent to the power-switching device that they actupon, unless this would result in a mal-operation.

• The relay settings shall be self-contained within the relay so that they can only bechanged at the relay, and not by a remote means. If ‘intelligent relays’ are used thenaccess to the settings shall be via the software and a MMI using a password or similarlysecure method.

Revision A

• Where trip circuit supervision is required, the trip circuit wiring including the lockoutrelay shall be arranged so that the supervising relay operates if any of the wiring becomesdiscontinuous. Supervision relays shall monitor the trip circuit when the CB is open orclosed, by a normally energised ‘HEALTHY TRIP’ indicating lamp.

• Tripping of the incoming, generator, bus-section and switchboard inter-connector CBsshall be by two circuits simultaneously, one direct from the protective relay and thesecond through the lockout relay.

• The supplier shall design the relay protection schemes so that they do not operate when:-

i) Transient currents or voltages exist in adjacent circuits, i.e. EMI.

ii) Third harmonic currents or voltages exist in earth fault protection circuits, either inthe steady state or in the transient state.

• The protection of motors shall be arranged that once the motor has tripped on fault, itshall stay tripped until the fault is cleared, its protective relay reset and the contactor isre-energised.

• The manufacturer shall clearly state whether any external resistances or impedances arerequired in the protection circuits. Details shall include ohmic values, rated powerdissipation, and calculations for knee-points voltages, CT and VT burdens, wiring routeimpedance and the like.

12.1.1 Additional Requirements for Motor Starters

All motors shall have under-voltage protection.

All motors shall have phase failure or single-phase protection.

All motor starters shall have operations counters.

Overloading protective relays shall be fed from CTs where the full load current of the circuitis equal to or greater than 30 amps.

12.1.1.1 Motor overload protective relays and thermistor control units.

Overload protection relays shall comply with IEC 947 [36].

Overload protection relays shall be installed in all phases and shall include protection againstsingle phasing and be of the time delayed type. The response to single phasing shall be atleast 10% faster than for balanced three-phase overloading. The relays shall be of the ambienttemperature compensated type. They shall be equipped with manually reset facilities on thefront of the compartment and be accessible without opening the assembly. An inadvertentreset action shall not trip a circuit.

Overload protection relay having a 3-pole thermal image characteristic for the motor, andambient temperature compensation, fed from current transformers. These relays shall bemanually re-set from the front of the cubicle.

The overload characteristic shall have ‘hot’ and ‘cold’ images of the motor being protected.

The overload characteristic of the motor protective relay shall allow the motor to be started atleast twice in succession from its cold state, and re-started at least once from its hot state. Inboth situations the motor voltage during starting shall be assumed to be 80% of its nominalvalue.

Revision A

Thermistor type of motor protection shall be stated in the data sheets if it is to be used.Otherwise line current activated overload relays shall be used. For motors with operatingconditions beyond those covered by overload relays, special protection systems may beconsidered, e.g. installation of thermistor temperature sensors in the motor windings with itsrelay installed in the switchgear compartment. Agreement shall be reached with QGPC in thetendering stage.

Bimetallic thermal relays shall not be used.

For motors with running up times in excess of 5 seconds saturable current transformers incombination with a standard nominal 1 amp or 5 amp relay shall be provided. Alternativelyan electronic protection relay with a suitable protection curve shall be supplied.

Motors may be Type of Protection Ex‘e’ for hazardous area applications, in which caseQGPC shall make this requirement clear in the data sheets for the motors and the SWGR. Themanufacturer shall provide electronic protective relays that will have comprehensive and fullyadjustable characteristics to match the thermal characteristics of the motor. Overload relaysprotecting electric motors of the Ex ‘e’ type installed in Zone 1 areas, shall have acurrent/time characteristic below the maximum locked rotor time (Te). The (Te) time shall beindicated on the schedule attached to the requisition, and an approved testing authority such asBASEEFA or PTB shall certify it. Full details shall be submitted to QGPC at the tenderingstage.

12.1.1.2 Motor Earth Fault Protection

Motors having a full load current of 30 amps and above shall be fitted with earth faultprotection relays of the core balance type, which shall cause all three-phase currents to bedetected and disconnected. Relays shall be manually resetable after opening of the assemblycompartment cover. The relays shall have an earth fault current sensitivity based upon amaximum level of 3% of the name plate current of the motor. If the sensitivity exceeds 6amps, then 6 amps shall be used. If the sensitivity is less than 30 milli-amps, then 30 milli-amps shall be used.

Each earth fault protection relay shall be equipped with a lamp on the tray or compartmentdoor, which shall be illuminated when the relay has tripped.

Each earth fault protection relay shall be equipped with a test button on the tray orcompartment door.

12.1.1.3 Motor Restarting Facilities

The restart control scheme if required shall be stated on the data sheets or in the requisitionand shall be in accordance with Appendix L of ES.2.03.0001 [50], see also (11).

Restart relays shall be included only for those individual motors that are indicated on acorresponding schedule attached to the requisition.

Revision A

12.2 Indicating Instruments.

Electronic protective relays may have a ‘read out’ facility that may be adequate to replace theuse of separate indicating instruments e.g. ammeters, active power meters, voltmeters. If themanufacturer proposes this alternative then he shall describe it in considerable detail at thetendering stage, and it shall be approved in writing by the QGPC. Otherwise indicatinginstruments and lamps shall include the following as appropriate : -

• Flush-mounted to IEC 51 [12] Class Index 2.5.

• All panel-mounted meters shall be square pattern, approximately 100 x 100 mmdimensions and shall be easily readable from a distance of two metres.

• All panel-mounted meters shall have scales marked with the actual quantities beingindicated, not per-unit nor percentage.

• External zero adjustment shall be provided on all instruments.

• If called for on the data sheets, instruments shall have red coloured index pointers, whichshall be adjustable by means of a special tool.

• With the exception of remote ammeters, fuses or MCBs shall protect all other remoteinstruments.

• Remote ammeters shall be fed from current transformers.

• If an ammeter is required for a motor it shall be fed from the yellow phase currenttransformer. Other circuits e.g. generator incomers, transformer incomers, switchboardincomers, shall have three ammeters or one ammeter in combination with a special make-before-break 4-position selector switch and four current transformers, so that the threeline currents and the neutral current can be displayed.

• Ammeter scales shall be selected so that the full-load current appears between 50 % and80 % of the full-scale angular deflection.

• Ammeters for motors shall have suppressed scales at the high levels of currents, so thatat least 8 x times full load current can be seen on the ammeter without it being damaged.

• Ammeters may be analogue (e.g. moving iron) or digital.

• Incoming units shall be equipped with a voltmeter and a 3-position selector switch so thatthe three line-to-line voltages can be displayed. The voltmeters may be analogue (e.g.moving coil) or digital.

• Provision shall be made for all alarms and trip indications to be transmitted to anannunciation panel in a remote CCR, including the wiring of all such signals to terminalblocks, see (9.10) and (9.14).

• Provision shall be made for including energy meters, i.e. kWh meters, in the incomingcircuit breaker cubicles. This provision shall include bus wiring, terminal blocks, voltageand current signals, and space for fixing the meter to the panel. The requirement formeters themselves shall be stated by QGPC on the data sheets.

Revision A

12.3 Indicating Lamps

All power circuit breakers, motor starters and contactor feeders shall be fitted with panelmounted lamps to indicate their status and the state of their tripping circuits (‘trip supplyhealthy’).

Indicating lamps shall comply with the following : -

• Lamps shall be of the non-filament type, e.g. multi-segment LED or neon.

• Flush mounted.

• Colours to be in accordance with IEC 73 [14].

• Lamps operating at different voltages shall be non-interchangeable.

• The nominal voltages of the lamps shall be at least 110 % that of the nominal supplyvoltage of their circuit.

12.4 Current Transformers

Current transformers shall comply with IEC 185 [15] and the following : -

• The rated primary currents shall be selected from the [15] preferred values unlessspecified on the data sheets or single line diagrams.

• All remote ammeter circuits shall be fed from 1 amp secondary windings. Their accuracyshall be as a minimum Class 1 to [15], unless otherwise specified on the data sheets.Their magnetic saturation characteristics shall be such that meters and instruments arenot damaged due to the flow of fault currents in the main power conductors.

• All energy metering circuits shall be fed from 1 amp secondary windings, having aminimum VA rating of 10. Their accuracy shall be Class 3 to [15] for outgoing circuitsCTs supplied as part of the SWGR, and Class 1 for incoming circuits or if supplied forany purpose from a Third Party. Any other requirements such as the use of Class X shallbe specified on the data sheets. The saturation factor ‘n’ shall be 5 or less to preventdamage to their connected devices when high fault currents flow.

• All protective relay circuits shall be fed from 1 amp secondary windings. Their accuracyshall be Class 10P to [15], unless otherwise specified on the data sheets.

• Each current transformer shall have only one secondary winding.

• Only standard ratios shall be used.

• A rated short time current at least equal to that of the SWBD for the let-through current,and rated duration of no less than one second. Unless otherwise approved by QGPC theprimary winding shall match the current of the CB or contactor.

• Separate CTs shall be used for metering, indication and protection.

• The manufacturer may be requested to submit detailed calculations to confirm that theVA ratings of the CTs are adequate to operate their relays under worst-case faultconditions.

Revision A

• The manufacturer shall be responsible for ensuring that the characteristics of the CTsand VTs are matched to the protective relays. The manufacturer shall provide uponrequest all the details that are necessary to match his devices to corresponding devicesprovided by third parties, for example, CT’s for restricted earth fault protection,interposing CT’s.

• Bar type primary windings shall be used for CTs.

• Current transformers shall have 1-amp secondary windings, unless specified otherwise onthe data sheets for special circuits.

• All CT ratios and ratings shall be stated on the data sheets.

• Test Certificates and magnetic saturation characteristics of each CT shall be submittedby the manufacturer, shortly after the purchase order has been placed.

• CTs on outgoing circuits in particular shall be accessible safely without having to de-energise the bus bars in the cubicle.

• CT secondary windings shall earthed at one point through a removable link, which shallbe easily accessible for testing.

• CT secondary connections shall be made on to screwed terminals, slide-on types are notacceptable.

• Current analogue transducers shall have an output current signal of 4 – 20 mA d.c.

Note 12.4a : - Metering in this context relates to consumption of energy and electricitytarrifing.

12.5 Voltage Transformers

Voltage transformers shall comply with the following : -

• Their accuracy shall be Class 1 for measurement functions, Class 3P for protective relayfunctions and Class 0.5 for generator AVR excitation control functions, to IEC 186 [16],unless otherwise specified on the data sheets.

• For three phase purposes VTs shall have double wound star-to-star three phase windings.The primary winding star point shall be connected to the supply neutral. The secondarywinding star point shall be earthed, and an earthed metal screen shall be providedbetween the windings.

• Three phase and single phase VT secondary windings shall earthed at one point through aremovable link, which shall be easily accessible for testing.

• Single phase or special types of VTs shall be specified on the data sheets or on the singleline diagrams.

• The secondary winding nominal voltage shall be 110 VAC between phases unlessotherwise stated on the data sheets or on the single line diagrams.

• Three-phase VTs shall have 3-limb cores.

• Removable HRC fuses or MCBs shall protect VT primary windings.

• VTs shall not be loaded to more than 75 % of their rated output, based on the informationgiven by QGPC at the time the purchase order is placed.

Revision A

•• Voltage analogue transducers shall have an output current signal of 4 – 20 mA d.c.

12.6 Fuses for LV Circuits

Fuses, if used, shall comply with IEC 269-1 and 2 [20] and shall be supplied in shroudedwithdrawable carriers with fixed bases and be moulded in black material. The links shall benon-interchangeable with the neutral links and the earth links.

12.7 Neutral Links for LV Circuits

Neutral links, if used, shall be supplied in shrouded withdrawable carriers with fixed basesand be moulded in white (preferred colour) material. The links shall be non-interchangeablewith the fuses and the earth links.

12.8 Earth Links for LV Circuits

Earth links, if used, shall be supplied in shrouded withdrawable carriers with fixed bases andbe moulded in green (preferred colour) material. The links shall be non-interchangeable withthe fuses and the neutral links.

12.9 Control Relays, Devices and Control Contactors

Control relays and control contactors shall not be of the plug-in type, and shall comply withIEC 947-5-1 [36].

Control relays shall operate correctly when their coil supply voltages vary between 85% and110% of their nominal values, as measured at the bus bars. (The nominal coil voltage shouldequal the nominal supply voltage).

Control relays shall remain energised without chatter at 75% supply voltage, as measured atthe bus bars.

They shall incorporate mechanical or LED indication of their energisation.

12.10 Interposing Control Relays

To avoid problems of voltage drop in the field cabling used for control of power contactors ofmotor starters and plain feeders, it is required that interposing relays be used in conjunctionwith these contactors. Their functions will be to control the ‘on’ and the ‘off’ states of themain or power contactors. The manufacturer shall fit these interposing relays into each tray orcubicle as required. These shall also be indicated by QGPC in an appropriate schedule in therequisition.

12.11 Push-button Switches

All push-button switches shall have a full shroud or be flush mounted to prevent inadvertentoperation, and shall comply with IEC 947-5-1 [36]. Unless otherwise stated in the data sheets,the ‘stop’ buttons shall be of the stay-put type, manually reset and coloured red.

Each outgoing tray or cubicle containing a power contactor shall be fitted with an externallymounted ‘stop’ or ‘open’ push-button on its door.

Revision A

12.12 Auxiliary Contacts for the Power Circuit Breakers and Contactors

Circuit breakers and contactors shall be provided with auxiliary switch contacts with thefollowing features : -

• The bank of auxiliary contacts shall be driven positively into both the open and closedpositions by the main device operating mechanism. Auxiliary contacts shall be wired tooutgoing terminal blocks and identified as shown on the manufacturer’s drawings.

• These contacts shall be in addition to those required for the control circuits within thecubicle.

• All auxiliary contacts shall be positioned to afford easy inspection and maintenance.

• All auxiliary switches and their circuits shall be capable of carrying a current of at least10 amps continuously.

• Unless stated on the data sheets the auxiliary switches shall be capable of breaking atleast a 5 amps inductive load at 110VDC, with a time constant of 20 milli-seconds.

• The manufacturer shall advise the current ratings of all auxiliary switches.

• The manufacturer shall advise in his tender documentation the maximum number ofnormally open, normally closed, changeover and convertible switches that can beattached to and be operated from each type of CB.

• Auxiliary switches for motor anti-condensation heaters shall be double-pole types.

• When specified on the project data sheets the auxiliary switch contacts for each motorheater supply shall be provided so that the heaters are energised when the main switchingdevice is ‘open’. When the main switching device is isolated, the heater supply shall alsobe isolated.

• It is preferred that all functions which use the auxiliary and racking switches shall do soin a direct manner. Repeat relays are not to be used, except for indication and alarmcircuits.

12.13 Test Facilities

An electrical test facility shall be provided for testing of secondary circuits and mainmechanisms of the withdrawable and fixed incomer CBs, bus-section CBs, contactor startersand contactor feeders when they are not in their ‘service’ positions. A ‘test’ position ispreferred. Such electrical testing shall include the control circuits. The manufacturer shalldetail his standard arrangements in his tender documentation. This shall incorporate theinterlocks specified in (9.13) above.

The QGPC preferred schemes are described as follows. One single phase, externally derivedsupply per bus bar section taken between the L2 phase and neutral and internally wired to theunits or by means of a lead, plug and socket arrangement. A ‘test’ switch and associatedcircuits shall be provided at each cubicle and tray.

The test facilities shall also include : -

• Facilities shall be provided to enable primary injection testing to be carried out.

Revision A

• Each SWBD shall incorporate voltage pressure test facilities for the bus bars and allincoming and outgoing circuits. The manufacturer shall supply one set of any test plugsnecessary for this purpose.

12.14 Heat Emission

The manufacturer shall submit heat emission data (in kilowatts) for each tier, assuming thepower circuits are all switched ‘on’ and are fully loaded, and that the anti-condensationheaters are switched ‘on’.

12.15 Control Circuit and Auxiliary Circuit Voltage Supplies

12.15.1 A.C. and D.C. Voltages

The control supplies for each section of main bus bar shall in general be separate, and shouldbe shown in the QGPC standard drawings and project drawings.

Note, the closing, tripping, indication, measurement and protection LV supplies may bedifferent at the various QGPC sites. Table 12.15.1.A shows the preferred voltages forparticular functions, however these shall be confirmed for each QGPC project and site.

Table 12.15.1.APreferred Voltages for Particular Functions

VoltageVolts

A.C. or D.C. Internal orExternal

Function

110 D.C. External Incoming and bus-section CB closing andtripping.

110 D.C. External Incoming and bus-section CB statusindication.

110 D.C. External CB trip circuit supervision110 D.C. External Power supplies to electronic relays110 A.C. External Power supplies to re-acceleration control

systems.110 A.C. Internal Motor starter controls* closing and tripping.110 A.C. Internal Fused contactor feeder controls* closing and

tripping.110 A.C. Internal Motor starter and fused contactor feeder,

status indication.240 A.C. 50 Hz External SWBD anti-condensation heaters.220 A.C. 60 Hz

110 or240220

A.C. or D.C.A.C. 50 HzA.C. 60 Hz

External CB spring charging motor. **

24 V D. C. External E. S. D. and F & G detection interface relaycoil supply.

Note 12.15.1a : - * These include the field control devices e.g. emergency stopbuttons.

Note 12.15.1b : - ** D.C. for incomers and bus-section CBs A.C. for all outgoingcircuits.

Revision A

Note 12.15.1c : - 50 Hz frequency is the QGPC standard, but 60 Hz is used inexceptional locations, e.g. North Field PS-4 Platform.

The static protection relays and the CB tripping coil circuits shall have their power suppliesderived from external UPSs.

12.15.2 Moulded Case and Miniature Circuit Breakers

Low power moulded case circuit breakers (MCCBs) shall comply with IEC 947 Part 2 [36].

Low power miniature circuit breakers (MCBs) shall comply with IEC 898 [34].

QGPC shall state clearly in the requisition whether or not MCCBs are to be used, and whetherthe ‘intelligence’ described below is also required.

If MCCBs are required to communicate through a network in an ‘intelligent’ manner similarto the ‘intelligent relays’ described in (12.1) then they shall be provided with the followingancillary devices : -

• A tripping unit capable of two-way communication by network ‘twisted-pair’ cables, forremote monitoring, and ‘on’ and ‘off’ control. This unit may be required to be of themicroprocessor-based type, which shall be at least capable of monitoring : -

+ Peak kW demand, + Actual kW demand,

+ Total kWh energy consumed, + Power factor,

+ Percentage harmonic current in each line and neutral,

+ Total harmonic distortion in the supply.

• The tripping unit shall have a programmable address and a testing facility of the hand-held or portable computer type.

• The communicable parameters shall include at least, protective relay element settings,CB status, measured variables used in the protective device elements, memory failuretesting, trip and alarm events, test push button operation, communication errors.

The manufacturer shall provide full details of all the options that are available in his tenderdocumentation.

Revision A

13.0 Inspection

The SWGR shall be inspected by QGPC or his nominated representative, called the Inspector.

The manufacturer shall allow the Inspector all reasonable access to his factory anddocumentation with regard to the SWGR at any times during its manufacture. The Inspectorshall give no less than 15 working days notice for pre-planned inspection visits. The Scope ofInspection shall be agreed in advance between QGPC and the manufacturer.

Approval by the Inspector shall not relieve the manufacturer of his responsibilities under theterms of the purchase order and this specification and its accompanying documents.

The SWGR shall be inspected as soon as it arrives at the QGPC site. Equipment sensitive tohumidity shall be kept dry and its dryness checked before site tests are performed.

Revision A

14.0 Testing Specifications

14.1 General

The manufacturer shall have a QA / QC system based on ISO 9000 [39] controlling thequality of the design and assembling work during all stages of the production process.

14.2 Type Tests

Type tests shall be carried out, or shall have been carried out previously as described in forexample (8.8). Type Testing shall be in accordance with IEC 947 [36]. The additionalrequirements specified for QGPC purposes (e.g. bus-bar insulation, diversity factor, highambient temperature, etc.) shall be taken into consideration.

Motor starters and contactor-fuse-isolator combinations shall be tested in accordance withIEC 947 [36] and shall include special tests to verify that the Type 2 co-ordination detailed in(11.1) has been achieved.

A switch of each type and rating shall have been Type Tested in accordance with IEC 947[36], and certificates shall be made available to QGPC upon request.

Certificates shall be available at the tender stage.

Certificates shall be issued by independent testing laboratories.

Adapter chambers or cubicles containing non-withdrawable equipment such as bus bars,transformers, terminations, shall be included in the same certification as the main equipment.

14.3 Witnessed Routine Testing

Before the SWGR leaves the factory the manufacturer shall carry out the witnessed routinetests, also called the Factory Acceptance Tests or FATs, in accordance with IEC 439-1 [26]on the total assembly or parts thereof if the SWGR is to be delivered at different timeintervals, and the results shall be recorded in a test report.

The manufacturer shall provide documents to show that all the electronic and solid stateprotective relays that require an external auxiliary power supply have under gone a ‘soak’test, from such a supply, for a period of not less than 48 hours.

The manufacturer shall provide documents to show that all the energy meters (kWh) havebeen tested by their makers.

Witnessed tests shall be carried out on every cubicle and every tier of the assembled SWGR.

These tests shall take place at the factory where the SWGR was manufactured. Transportablesections may be wired together instead completing the bus-bar joints.

Contactors shall be tested in accordance with IEC 947 [36].

Disconnectors and isolators shall be tested in accordance with IEC 947 [36].

Switches shall be tested in accordance with IEC 947 [36] at the manufacturer’s factory.

Revision A

VTs shall be subject to the Routine Tests of IEC 186 and 186A [16], and tested forcorrectness in ratio and polarity.

CTs shall be subject to the Routine Tests of IEC 185 [15], and tested for correctness in ratioand polarity.

Type Test certificates shall be made available for inspection at the Routine Testing occasion,see also (8.8), and (11.1) for fused motor starters.

Adapter chambers or cubicles containing non-withdrawable equipment such as bus bars,transformers, terminations, shall have the same certification as the main equipment.

Witnessed tests shall be carried out on every cubicle and every tier of the assembled SWGR.These tests shall take place at the factory where the SWGR was manufactured.

The manufacturer shall give QGPC at least 15 working days notice of the intended datefor the routine tests, which shall be witnessed by QGPC or his nominated representative.

The Inspector may also be present at these tests. The following routine tests shall beperformed to the satisfaction of QGPC : -

The SWGR shall be visually inspected for technical execution and conformity with the latestissue of the approved drawings and documents of the requisition. Spot checks shall be made toverify the following : -

• Completeness of the data on the general equipment nameplate.

• Degree of protection of the enclosure.

• Degree of protection within the compartments.

• Effectiveness of safety shutters, partitions and shrouds.

• Effectiveness of operating mechanisms, locks and interlocking systems.

• Insulation of the bus-bar system.

• Creepage distances and clearances.

• Proper mounting of components.

• Internal wiring, trunking and cabling systems.

• Correct wiring of main and auxiliary circuits.

• Suitability of clamping, earthing and terminating arrangements.

• Correct labelling of functional units and auxiliary devices.

• Availability of the earthing system throughout the SWGR.

• Inter-changeability of electrically identical components.

• Non-inter-changeability of mechanically identical but electrically different components.

Revision A

The following tests shall be witnessed : -

• The insulation resistance test shall be carried out separately between each phase and theneutral against the earth, with the remaining phases and neutral connected to earth. Thesetests shall require all the manually and latched type switching devices in their closedpositions and with all the main fuses installed. The insulation resistance measured shallbe at least 5 mega-ohms when a d.c. voltage of 1.1times the rated a.c. voltage of theequipment is applied.

• Dielectric tests to IEC 439-1 [26], but for 1 minute. The test voltage shall be at least,2500 V a.c. for the main power circuits, and 2 times the rated voltage plus 1000 V a.c.with a minimum of 1500 V a.c. for the control and auxiliary circuits.

• Operational tests of protective relays and circuits by primary injection of current orvoltage as required.

• Interchangeability test.

• A detailed simulated test of the secondary-selective scheme, where provided.

The manufacturer shall provide all the necessary test equipment, which shall have beencalibrated within one year prior to the date of the tests.

The manufacturer shall issue a comprehensive report of the witnessed tests, within tenworking days of the completion of the tests.

Revision A

15.0 Documentation

All documents shall be in English language.

15.1 Design Documents to be Provided by the Manufacturer

15.1.1 Tender Documentation

Data sheets that require the manufacturer to provide information on them shall be completedas required by QGPC, and submitted as part of the manufacturer’s tender documentation.

The requirements in (5.0), (6.1), (8.1), (8.2), (8.3), (8.5.1), (8.7), (9.2), (9.3.1), (9.14), (9.21),(9.23), (10.2.1), (10.2.2), (11.1), (12.0), (12.1), (12.1.1.1), (12.2), (12.12), (12.13),(12.15.2), (14.2) and has listed below, for submissions as tendering information shall bestrictly complied with, because this information will be used by QGPC in the tenderevaluation process.

• Data sheets completed where necessary

• Overall dimensions, plans and elevation drawings.

• Base and skid dimensions.

• Lifting arrangements.

• Jacking points.

• Total weight including withdrawable switching devices.

• Cable entry positions.

15.1.2 After the Purchase Order has been placed

The manufacturer shall supply at least the following documents shortly after receipt of theorder : -

• Preliminary one-line or single-line diagram(s).

• Preliminary LOGIC diagrams for the control and protection of all the different types ofpower circuit breakers and contactors.

• Preliminary schematic diagrams of all the different types of circuits.

• Preliminary SWGR arrangements or layout drawings showing main circuits, maindimensions, front elevations, front panel equipment layouts, floor plans and shippingsections.

• Preliminary wiring, termination and interconnection diagrams for HV, LV, internal (bus-wire) and external (or field) circuits.

• Preliminary cable entry, glanding and securing detail.

• Minimum clearances around the SWGR for ventilation and safety during operation andmaintenance.

• Total mass of the SWGR and of the individual shipping sections.

• Copies of TYPE TEST CERTIFICATES for the SWGR and its components, see also(8.7) and (8.8).

Revision A

All documents shall show the relevant purchase order number, item and the manufacturer’sreferences, dates, and shall be distributed as specified in the requisition.

15.2 Documents for the Delivery, Installation, Operation and Maintenance

The manufacturer shall supply at least the following documents after receipt of the order andbefore the FAT takes place : -

• Instruction manuals for, transportation, long term storage at site, installation,commissioning and maintenance. These documents must be specific to the equipment aspurchased and not of a general nature.

• Comprehensive list of commissioning spare parts.

• Comprehensive list of spare parts, cross-referenced to the cubicle equipment layoutdrawings, for use after commissioning has been completed and which will cover a periodof two years.

• Drawing of the General Equipment Nameplate, see (9.20.2).

The manufacturer shall supply the following documents after the FAT takes place : -

• Report of the Witnessed Routine (FAT) Tests.

• Final revisions of all of the above ‘preliminary’ documents.

All documents shall show the relevant purchase order number, item and the manufacturer’sreferences, dates, and shall be distributed as specified in the requisition.

16.0 Packing

Packing of the SWGR shall prevent ingress of moisture or damage to the equipment protectivefinishes during transportation and storage.

SWGR packing shall be suitable for unheated indoor storage. The manufacturer shall adviseof any requirement for energisation of the anti-condensation heaters.

Labeling of the packaging will be detailed in the requisition documents.

SWGR shall only be crated if specially requested in the requisition documents.

Revision A

17.0 Approval to Deviate

Strict compliance with this standard specification is required. Any deviation must obtain priorwritten approval from its custodian.

18.0 Revision History Log

A record or log shall be kept of the revision history of each engineering document, and beincorporated in the document’s accompanying electronic “readme” file [5]. In this way, thereshould be no need for a history log to be included in a document - only details of its latestapproved revision need be shown (note that the readme file will contain information about theparticular operating system plus application software versions which were used to create thedocument’s electronic file ; it can also include “help pages” in the form of background notesand explanations, where such details are considered of benefit to its reader).

The following is recommended for the contents of a document’s revision history log :-

Revision Number 0,1,2,3, etc.Prepared By/Date Name or reference indicator and date (ddmmmyy)Checked By/Date Name or reference indicator and date (ddmmmyy)Approved By/Date Name or reference indicator and date (ddmmmyy)Reason For Change Short description, with “change request reference” if availableRelease/Date Release/transmittal reference and date (ddmmmyy)

19.0 Bibliography

19.1 Common References

Identifier Standard Revision DescriptionCode andNumber

[1] ISO 216 1989 Writing Paper and Certain Classes of1st Edition Printed Matter. Trimmed Sizes - A and B Series.

[2] ES.0.10.0001 Rev 0 Standard Database - Key Words & Phrases. [3]ES.0.10.0002 Rev 0 Standard Database - Acronyms.

[4] ES.0.07.0010 Rev 0 Engineering Document Classifications. [5] ES.0.06.0021 Rev 0 Electronic “Read Me” Files.

Revision A

19.2 Technical References

The following technical standards and codes of practices shall be used : -

Identifier Standard Revision DescriptionCode andNumber

[10] IEC 38 IEC Standard voltages.

[11] IEC 50 International electro-technical vocabulary.

[12] IEC 51 Recommendations for direct acting indicatingelectrical measuring instruments and theiraccessories. Part 2 : Special requirementsfor ampere meters and volt meters.

[13] IEC 59 IEC Standard current ratings.

[14] IEC 73 Indicating lamps.

[15] IEC 185 Current transformers.

[16] IEC 186 Voltage transformers.

[17] IEC 227 PVC cables up to 750V.

[18] IEC 228 Conductors for insulated cables.

[19] IEC 255 Electrical protection relays.

[20] IEC 269 Low-voltage fuses with high-breakingcapacity.

[21] IEC 298 A.C. metal-enclosed switchgear andcontrolgear for rated voltages above 1 kVand up to and including 52 kV.

[22] IEC 332 Tests on electric cables under fire conditions.

[23] IEC 363 Short-circuit current evaluation with specialregard to rated short-circuit capacity ofcircuit breakers in installations in ships.

[24] IEC 417 Graphical symbols for use in equipment.

[25] IEC 420 High-voltage alternating current switch-fusecombinations.

[26] IEC 439 Factory built assemblies of low-voltageswitchgear and controlgear.

Revision A

[27] IEC 445 Identification of apparatus terminals andgeneral rules for a uniform system ofterminal marking, using an alphanumericnotation.

[28] IEC 446 Identification of insulated and bareconductors by colours.

[29] IEC 473 Dimensions for panel-mounted indicating andrecording electrical measuring instruments.

[30] IEC 529 Classification of degrees of protectionprovided by enclosures. ( IP system ofnumbering ).

[31] IEC 664 Insulation coordination for equipment withinlow-voltage systems.

[32] IEC 688 Electrical measuring transducers forconverting a.c. electrical quantities into D.C.electrical quantities. Part 1: General purposetransducers.

[33] IEC 801 Electromagnetic compatibility for industrialprocess measurement and control equipment.Part 3: Radiated electromagnetic fieldrequirements.

[34] IEC 898 Circuit-breakers for over-current protectionfor house-hold and similar installations.

[35] IEC 909 Short-circuit current calculation in three-phase AC systems.

[36] IEC 947 Low voltage switchgear and control gear.

[37] IEC 1000 Electromagnetic compatibility (EMC)

[38] EN 50085 Cable trunking systems and cable ductingsystems for electrical installations Part 1:General requirement ratified European text.

[39] ISO 9000 Quality management and quality assurancestandards - guidelines for selection and use.

[40] EN 55022 Limits and methods of measurement of radiointerference characteristics of informationtechnology equipment.

[41] BS 4800 Specification for paint colours for buildingpurposes.

[42] BS 4999 General requirements for rotating electricalmachines.

Revision A

Part 112: Specification for startingperformance of single-speed three-phase cageinduction motors.

[43] BS 6231 PVC-insulated cables for switchgear andcontrol wiring.

[44] IEEE C37.2 IEEE standard electrical power systemdevice function numbers.

19.3 QGPC Documents

[50] ES.2.03.0001 Electrical engineering philosophy.

[51] ES.2.14.0060 Secondary selective systems.

19.4 Periodic Revision of Reference Documents

At the time of publication of this specification the revision of each of the above references, as theycross-relate to the revision of this document, were valid. As all references are subject to changefrom time to time, the reader is required to first check with the custodian of this document to findout the latest “cross-revision” status with respect to the above bibliographic list.

Revision A

APPENDIX A

MINIMUM CIRCUIT EQUIPMENT LISTFOR LV SWITCHBOARDS

CONTENTS

A.1 Low voltage generator incomers.

A.2 Transformer incomers, primary circuit for solid earthed secondary windings.

A.3 Transformer incomers, secondary circuit for solid earthed secondary windings.

A.4 Plain incomers and interconnectors.

A.5 Bus-section circuit breakers.

A.6 Motor starter feeders using circuit breakers

A.7 Motor starter feeders using fuses and contactors

A.8 Static load feeders using fuses and contactors

Note A.a : - These lists are to be used as the basis for project requirements andwhere the tender or purchase order documents do not define the circuitrequirements in detail.

Note A.b : - Modern electronic protective relays may have facilities which incorporatesome of those listed, e.g. digital indication of variables. QGPC shallapprove any such incorporation.

Note A.c : - The requirements for protective relays are derived from the Table J.A inApprendix J of QGPC document ES.2.03.0001 [50].

Note A.d : - The definitions of protective relay ANSI / IEEE numbers are given inAppendix K of QGPC QGPC document ES.2.03.0001 [50]. Numbers 95, 96and 97 are used by QGPC for particular cases.

Revision A

A.1 Low Voltage Generator Incomers.

Each cubicle shall be equipped with at least the following facilities : -

Indication and metering.

a) 1 - Ammeter.

b) 1 - Ammeter selector switch.

c) 1 - Voltmeter.

d) 1 - Voltmeter selector switch.

e) 1 - Kilo-watt meter.

f) 1 - Kilo-var meter.

g) 1 - Power factor meter.

h) 1 - Frequency meter.

Analogue transducers if required by PMS or SCADA.

i) 1 - Current transducer.

j) 1 - Voltage transducer.

k) 1 - Kilo-watt transducer.

l) 1 - Kilo-var transducer.

Control devices.

m) 1 - Set of necessary auxiliary switches.

n) 1 - Local / off / remote control selector switch for open and close operatinglocations.

o) 1 - Open / neutral / close local control switch.

p) 1 - Set of indicating lamps for, tripped, closed, open, protection operated, tripsupply healthy.

q) 1 - Open / close mechanical indicating flag.

r) 1 - Operations counter.

Current and voltage transformers.

s) 2 - Sets of 3 off CTs for operating differential (64) relays which will be mountedremote from the switchboard. These CTs may be free-issue by a third party.

See Note A.1a.

t) 1 - Set of 3 - phase VTs for operating protective relays, e.g. (27, 32, 40, 59, 51V,81).

u) 1 - set of 3 - phase VTs for indication.

v) 1 - set of 3 off CTs for indication.

Revision A

Protective relays.

w) 1 - 86G Trip and lockout relay for the generator circuits.

x) 1 - 95 Trip circuit supervision relay (95, see Note A.d ).

y) 1 - 26 Stator winding temperature relay.

z) 1 - 27 Under-voltage relay.

aa) 1 - 32 Reverse power relay.

bb) 1 - 40 Loss of excitation relay.

cc) 1 - 51V Voltage restrained over-current relay.

dd) 1 - 51G Star point un-restricted earth fault relay.

ee) 1 - 58 Excitation diode failure relay.

ff) 1 - 59 Over-voltage relay.

gg) 1 - 64 Restricted earth fault relay.

hh) 1 - 81 Under and over-frequency relay.

ii) 1 - 87 Generator differential current relay, 3-phase type. See Note A.1a.

Note A.1a : - A second set of 3 off CTs may be required for generators rated 1000kW and above, for use with a 87 relay.

Revision A

A.2 Transformer incomers, primary circuit for solid earthed secondary windings.

These transformers will normally supply a LV switchboard from a HV switchboard.

These transformers are upstream of the LV switchboard, hence the list below is not partof the Scope of Supply of the LV switchboard, but has been included for informationonly.

The following relates to the primary winding circuit of the transformer. There will also beequipment needed in the switchgear for the secondary circuit, see (A.3).

Each primary circuit cubicle shall be equipped with at least the following facilities : -

Indication and metering

a) 1 - Ammeter.


c) 1 - Kilo-watt meter, optional.

d) 1 - Power factor meter, optional.

f) 1 - Buchholz relay alarm and trip indicator.


e) 1 - Current transducer.

f) 1 - Kilo-watt transducer.

g) 1 - Kilo-var transducer.

Control devices

h) 1 - set of necessary auxiliary switches.

i) 1 - Local / off / remote control selector switch for open and close operatinglocations.

j) 1 - Open / neutral / close local control switch.

k) 1 - Set of indicating lamps for, tripped, closed, open, protection operated, tripsupply healthy.

l) 1 - Open / close mechanical indicating flag.

m) 1 - Operations counter.

Current and voltage transformers

n) 1 - set of 3 off CTs for operating the differential (87, see Note A2.a) relay.

o) 1 - 3-phase interposing CT may be required to match the circuits of the (87, seeNote A2.a) relay above.

p) 1 - core balance CT for operating over-current (51N) relay.

q) 1 - set of 3 off CTs for operating over-current (50/51) relays.

r) 1 - set of 3 off CTs for indication.

Revision A

Protective relays

s) 1 - 86 Trip and lockout relay for the transformer secondary circuits.

t) 1 - 95 Trip circuit supervision relay (95, see Note A.d ).

u) 1 - 23 Alternative location of cooling fan controller or relay.

v) 1 - 50 / 51 Over-current relay.

w) 1 - 51N Un-restricted earth fault relay.

x) 1 - 87 Transformer differential current relay, 3-phase type, see Note A2.a.

y) 1 - Buchholz relay alarm and trip relay.

Note A2.a:- Not required for transformers having ratings below 5 MVA.

Revision A

A.3 Transformer incomers, secondary circuit for solid earthed secondary windings.

The following relates to the secondary winding circuit of the transformer. There will also beequipment needed in the switchgear for the primary circuit, see (A.2).

Each secondary circuit cubicle shall be equipped with at least the following facilities : -


a) 1 - Ammeter.


c) 1 - Voltmeter.


e) 1 - Kilo-watt meter, optional.

f) 1 - Kilo-watt-hour meter, optional.

g) 1 - Power factor meter, optional.

Analogue transducers if required by PMS or SCADA.NONE

Control devices

l) 1 - set of necessary auxiliary switches.

m) 1 - Local / off / remote control selector switch for open and close operatinglocations.

n) 1 - Open / neutral / close local control switch.

o) 1 - Set of indicating lamps for, tripped, closed, open, protection operated, tripsupply healthy.

p) 1 - Open / close mechanical indicating flag.

q) 1 - Operations counter.


r) 1 - set of 3 off CTs for operating the differential (87) relay which may be mountedin the primary circuit switchboard. See Note A.3a. These CTs may be free-issue from a third party.

s) 1 - 3-phase interposing CT may br required to match the circuits of the (87) relayabove, see Note A.3a.

r) 1 - set of 3 off CTs for operating the restricted earth fault (64) relay, see NoteA.3b.

r) 1 - CT for operating the over-current (64) relay, to be fitted in the star-point toearth circuit of the secondary winding, see Note A.3b.

r) 1 - CT for operating the over-current (51G) relay, to be fitted in the star-point toearth circuit of the secondary winding, see Note A.3c.

t) 1 - set of 3 - phase VTs for indication, optional.

u) 1 - set of 3 off CTs for indication, optional.

Revision A

Protective relays

v) 1 - 86 Trip and lockout relay or function.

w) 1 - 95 Trip circuit supervision relay (95, see Note A.d ).

x) 1 - 51G Star point un-restricted earth fault relay, see Note A.3c.

y) 1 - 64 Restricted earth fault relay or function, see Note A.3b.

Note A.3a:- Not required for transformers rated 5 MVA and below, for use with a (87)relay.

Note A.3b:- Restricted earth fault protection, not required for transformers rated 1.25 MVAand below.

Note A.3c:- Un-restricted earth fault protection, required for transformers of all ratings.

Revision A

A.4 Plain Incomers and Interconnectors.

The following relates to the receiving end of a plain feeder, and to both ends of aninterconnector between two switchboards of the same voltage.



a) 1 - Ammeter, optional.

b) 1 - Ammeter selector switch, optional.

c) 1 - Voltmeter.


e) 1 - Kilo-watt meter, optional.

f) 1 - Kilo-watt-hour meter, optional.

g) 1 - Power factor meter, optional.


NONE

Control devices

h) 1 - set of necessary auxiliary switches.

i) 1 - Local / off / remote control selector switch for open and close operatinglocations.

j) 1 - Open / neutral / close local control switch.

k) 1 - Set of indicating lamps for, tripped, closed, open, protection operated, tripsupply healthy.

l) 1 - Open / close mechanical indicating flag.

m) 1 - Operations counter.


n) 1 - set of 3 off CTs for operating the over-current (51) relay, which also has anearth fault (51N) element.

o) 1 - set of 3 - phase VTs for indication, optional.

p) 1 - set of 3 off CTs for indication, optional.

Protective relays

q) 1 - 86 Trip and lockout relay or function.

r) 1 - 95 Trip circuit supervision relay (95, see Note A.d ).

s) 1 - 51 Over-current relay.

t) 1 - 51N Earth fault element or relay.

Revision A

A.5 Bus-Section Circuit Breakers.



a) 1 - LHS bus-bar voltmeter.

b) 1 - RHS bus-bar voltmeter.

c) 2 - Voltmeter selector switches.


d) 2 - Voltage transducers, optional.

Control devices

e) 1 - set of necessary auxiliary switches.

f) 1 - Local / off / remote control selector switch for open and close operatinglocations.

g) 1 - Open / neutral / close local control switch.

h) 1 - Set of indicating lamps for, tripped, closed, open, protection operated, tripsupply healthy.

i) 1 - Open / close mechanical indicating flag.

j) 1 - Operations counter.


k) 1 - set of 3 - phase VTs for indication.

Protective relays

l) 1 - 86 Trip and lockout relay for the transformer secondary circuits.

m) 1 - 95 Trip circuit supervision relay (95, see Note A.d ).

n) 1 - 25 Synchronising check relay, see Appendix B.

Revision A

A.6 Motor Starter Feeders Using Circuit Breakers.

See (10) for restrictions on the use of CBs for motor starters.

Each motor starter cubicle shall be equipped with at least the following facilities : -


a) 1 - Ammeter.


c) 1 - Current transducer.

Control devices

e) 1 - set of necessary auxiliary switches.

f) 1 - Local / off / remote control selector switch for open and close operatinglocations.

g) 1 - Stop / neutral / start local control switch.

h) 1 - Set of indicating lamps for, tripped, running, stopped, protection

operated, trip supply healthy.

i) 1 - Open / close mechanical indicating flag.

j) 1 - Operations counter.


m) 1 - core balance CT for operating over-current (50N) relay, see Note A.6a.

n) 1 - set of 3 off CTs for operating over-current (46/49/50) relays.

o) 1 - CT for indication.

Protective relays

p) 1 - (86) Trip and lockout function.

u) 1 - 50N Un-restricted earth fault relay.

The following functions may be combined into one relay

w) 1 - 27 Under-voltage relay.

x) 1 - 37 Under-current relay

y) 1 - 46 Negative phase sequence relay.

z) 1 - 49 Thermal image over-load relay.

aa) 1 - 50 Over-current relay.

bb) 1 - Shaft stalling relay.

cc) 1 - Number of starts limiting relay.

Note A.6a: - Not required for motors having full load current ratings below 30 amps, see(12.1.1.2).

Revision A

A.7 Motor Starter Feeders Using Fuses or MCCBs and Contactors.

As for A.6, but with the following additions : -

Protective relays

a) 1 - Fuse or MCCB fault operation relay for the main contactor combination.

b) 1 - Time delay relay to prevent the main contactor from opening before the fusesoperate, see (11.1). The supplier shall confirm whether this relay is needed.

A.8 Static Load Feeders Using Fuses or MCCBs and Contactors.

The following relates to the sending end of a static load feeder.

Additions and deletions may be needed to suit the particular load.



a) 1 - Ammeter, optional.


NONE

Control devices

b) 1 - set of necessary auxiliary switches.

c) 1 - Local / off / remote control selector switch for open and close operatinglocations.

d) 1 - Open / neutral / close local control switch.

e) 1 - Set of indicating lamps for, tripped, closed, open, protection operated, tripsupply healthy.

f) 1 - Open / close mechanical indicating flag.

g) 1 - Operations counter.


h) 1 - set of 3 off CTs for operating an over-current (50/51) relay, which also has anearth fault (51N) element.

i) 1 - CT for indication, optional.

Revision A

Protective relays

j) 1 - (86) Trip and lockout function.

k) 1 - 50 / 51 Over-current relay.

l) 1 - 51N Earth fault element or relay.

m) 1 - Fuse or MCCB fault operation relay for the main contactor combination.

n) 1 - Time delay relay to prevent the main contactor from opening before the fusesoperate, see (11.1). The supplier shall confirm whether this relay is needed.

Revision A

APPENDIX B

INTERLOCKING FOR DUAL FEEDERS TO SWITCHBOARDS

B.1 Momentary paralleling interlocking schemes

Note B.1a : - ‘Momentary paralleling interlocking schemes’ are also called‘ 2 - out of - 3 ‘ paralleling schemes.

Where the purpose of the switchboard is to supply production, essential or vital loads and ithas two or more sections of busbars, then the incoming and bus section circuit breakers shallbe provided with a momentary paralleling interlocking scheme. This is necessary to ensurethat a no-break transfer can be achieved when one circuit breaker is to be opened and apreviously open one is to be closed. When one closes the other shall open after a pre-set timedelay.

B.2 Interlocking Schemes for the Incoming Feeders

Transformer and plain feeders will normally be provided with circuit breakers at both ends.To ensure safe operation and the same switching sequence when feeders are to be energized,the following interlocking shall be provided between the ends :-

• The downstream circuit breaker must not be closed if the upstream circuit breaker isopen, i.e. Close the upstream circuit breaker first to charge the feeder.

• If the downstream circuit breaker is opened for faults, then it should back-trip theupstream circuit breaker (only if it is provided with protective relays).

• If the downstream circuit breaker is opened as a normal operation then the upstreamcircuit breaker shall remain closed.

• If the upstream circuit breaker is opened for any reason then the downstream circuitbreaker shall be back-tripped.

B.3 Interlocking Schemes for Bus-Section Circuit Breakers

Where a downstream multi-busbar section switchboard is fed with more than one feeder froma multi-busbar section switchboard upstream, then there exists a possibility that the feederscould carry unsynchronised supplies. This is due to the possibility that the upstreamgeneration or intake switchboard is being operated temporarily with an open bus-sectioncircuit breaker and hence the sections of its busbars could be unsynchronised and energised bygenerators or utility in feeds.

In order to prevent paralleling unsynchronised sources at a downstream location, by theclosure of a bus-section circuit breaker, or the operation of a momentary paralleling scheme, itis necessary that suitable interlocking will prevent such operations. Essentially this shall beachieved by taking status signals from the bus-section circuit breakers of the generation orintake switchboard, and sending them to each downstream switchboard that will be concernedwith such undesirable operations. The status signal(s) received at a particular downstreamswitchboard shall be wired into the closing circuits of the concerned circuit breakers, and itshall also inhibit the momentary paralleling scheme.

Revision A

B.4 Interlocking Schemes for 3 Bus-Section Switchboards, with a Centre-fed Generator

********************* To be written *********************

23-es.2.14.0015 rev a - lv switchgear & controlgear for use qatar

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