intruction manual of 500kv pt in dung quoc subs

7/27/2019 Intruction Manual of 500kV PT in Dung Quoc Subs

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APPROVEDVBIE.672834.025 IM

Power transformers.

Instruction on mounting, start-up

and operation.

VBIE. 672834.025 IM

2007



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Разраб. Золотарев Лит. Лист Листов

Проверил Решетняк 2 39

Н. контр Донец И н в . № п

о д л .

Утвердил Баурин

Power transformers.Instruction on mounting, start-up and

operation

CONTENTS

Introduction……………..………………………………………………………………………….. 31 Safety precautions……………………………………………………………………………….. 32 Work stages…..……….…………………………………………………………………………… 33 Acceptance and inspection of transport packages……………………………………………. 44 Transformer transportation to the site…………………………………………………………... 45 Moving on its own rollers………….……………………………………………………………… 5

6 Insulation estimation after transportation……………………………………………………….. 57 Storage…………………………………………………………………………………………….... 58 Preparation for mounting………………………………………………………………………….. 69 Mounting.…………………………………………………………………………………………… 710 Vacuum-free oil filling and topping-up of transformers………..………………………………. 1011 Vacuum oil filling…………………………………………………………………………………… 1012 Testing and

adjustment…………………………………………………………………………………………... 1213 Trial run and adjustment……………….………………………………………………………….. 13 Appendix А Requirements on transformer oil………………………………………………… 15 Appendix B List of the main technological equipment, instruments, fittings and materials

for transformer mounting…………………………………………………..…….. 17 Appendix C 6-35 kV bushing test circuit……………………………………..……...……….. 20 Appendix D Transformer inspection with lifting the removable tank part or the active

part…….………………………………………………………………………….. 21 Appendix E Additional treatment (drying, predrying) of transformer insulation…………… 23 Appendix F Recommendations for restoration of damaged paint coats on metal sur-

faces……………………………………………………………………………….. 30 Appendix G Features of transformer mounting at negative tempera-

tures…………………………………………….....................…………………….. 32 Appendix H Insulation moistening protection during transformer depressuriza-

tion………………………………....................................……………………… 31 Appendix I Control and evaluation of the transformer insulation condition……………….. 33

ATTENTION!

1) On transformer arrival to the site, it is necessary to follow the requirements of the present instruction to avoid insulation moistening (sections 3, 6, 7).

If transformer unsealing revealed, take urgent measures to restore sealing and determinedegree of insulation moistening to take further measures.

2) If, within work execution, any failure to follow the requirements of the present instruction has revealed, it is necessary to draw up the report (act) and to inform the Manufacturer.




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INTRODUCTIONThe present instruction is applied to power transformers, autotransformers and reactors (here-

inafter referred to as transformers) intended for general purpose, rated for voltage classes 110-750kV, and contains the main requirements as well as methods of performance of technological opera-tions as for transportation, unloading, storage, mounting and start-up of the transformers.

Additional and particular requirements as referred to the transformers with design features areprovided in operating documents on the specific transformer.

Works should be performed by skilled specialists in strict correspondence with the requirements

of operating documents (as a rule, to be supplied to the Customer in transport case № 1, unlessotherwise stated in the Contract).

1 SAFETY PRECAUTIONS

1.1 Guidelines stated in the present section serve as addition to general valid regulations andinstructions on safety measures for electric equipment operation, local instructions and rules to befollowed during preparation to mounting, installation, testing and commissioning of the transform-ers.

1.2 Take measures to remove nitrogen before man enters into the tank of transformer beentransported oil-free but filled with nitrogen.

1.3 Supervise continuously the staff performing the operations inside the transformer tank.1.4 Within the transformer depressurization with dry air supply into the tank, follow the specified

requirements:- personnel working inside the tank and close to open manhole should be provided with rather

warm (depending upon ambient temperature) and clean clothes;- avoid men’s work inside the tank for more than 4 hours per day and 20 hours per month. 1.5 During development of fire-fighting measures during mounting works, consider that trans-

former is fire risk equipment due to the fact that transformer oil and oil-impregnated paper of the

transformers is combustible material and could be inflamed within fire-hazardous works (welding,warming-up of the transformer).

Works should be performed by skilled team of specialists being specially trained and certi-fied.

Perform welding works on the transformer tank only after oil filling up to the level approxi-mately 250 mm above welding place to avoid oil vapour ignition. When welding for eliminationoil leaks, transformer should be under vacuum to ensure absence of leakage and safety weld-

ing.1.6 Earth the transformer tank for the period of mounting works.

Earth winding leads during oil filling or draining to avoid electric charge at transformer.

At transformer oil filling or draining, it is necessary to earth the winding leads to avoid electriccharge on the transformer. For transformers transported with oil, prior to mounting of current trans-former installations and bushings, earth the winding leads.

2 WORK STAGES2.1 Works on the transformer from the moment of unloading at the station (in the port) are sub-

divided in the present instruction for the following stages:- acceptance and inspection of transport cases (on arrival to the station or in the port of des-tination);- transportation to the site;

- moving on the rollers;- estimation of insulation after shipment (not later than in 10 days after transportation);- arrangement for storage (if necessary);- preparation for mounting;- mounting of components;- oil filling (topping-up);- testing and adjustment;- trial run and start-up.




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2.2 Scope of the main technological operations at each stage depends on kind of the trans-former shipment from the Manufacturer.

3 ACCEPTANCE AND INSPECTION OF TRANSPORT PACKAGES3.1 After arrival to unloading point (railway station, port, site) make visual inspection and accept

transport cases in accordance with shipping documents.3.2 During acceptance check condition of the transformer tank fasteners to the platform or

transporter floor: stoppers, thrusts, braces and other fixing devices. Mismatch of reference marksand upsetting of fasteners is the evidence of inadmissible mechanical affects within transportation.

3.3 Inspect transport cases as for:- absence of mechanical damages, signs of impacts;- absence of oil leakage traces;- availability and integrity of provided seals;- absence of depressurization of bushings, current transformer installations, cooling systemelements.

In case if any signs of unauthorized opening of the packing revealed, check complete set of deliv-ery of opened transport case.

3.4 After acceptance, jointly with transport company, draw up the report as for all mismatchesrevealed.

3.5 Check the transformer tank tightness:- with installed conservator – according to oil indicator of the conservator;- without conservator, being partially filled with oil – according to difference in pressure values

(«hissing» at loosening of one of the tank upper plugs);- without conservator, without oil – according to presence of excessive pressure (10 kPa min) of nitrogen in the tank.3.6 Prevention of insulation moistening. In case of unsealing, create nitrogen (or dry air) exces-

sive pressure 25 kPa in the transformer tank:- by nitrogen supply from the balloon, or air via silica gel air breather using compressor, or withhelp of air drying plant;- by pumping of oil into the tank, oil should correspond to the requirements of Appendix А.The transformer is considered to be sealed if pressure would not decrease for more than 2 kPa

after 3 h. In case of bigger decrease it is necessary to restore tightness.

4 TRANSFORMER TRANSPORTATION TO THE SITE

4.1 Selection of transportation method. If transformer is unloaded at other location than at site,the Customer should choose method of transportation to the site (highway freighter, sledge, andinherent carriages), procedure of loading, unloading, calculation of fastening, considering distance,local conditions and requirements of operation documents related to the specific transformer.

4.2 Procedure of the transformer unloading. Unloading is performed by crane of proper liftingcapacity. Places and layout of slinging are stated in the outline drawing.

The transformer can be unloaded without crane – by pulling off from the trailer on to the slipper tie using tractors via pulley blocks, over beams (rails) to be installed under the transformer bottom.The beams should be installed adjacent to the bottom stiffening girders. Number of installed metalbeams (rails) and their strength should ensure the transformer safety during unloading. For trans-former transport mass of the transformer up to 60 t it is necessary to provide at least 3 beams, thatup to 120 t – 3 beams min., transport mass under 220 t requires at least 4 beams, that above 220 t – not less than 6 beams.

If transformer is to be unloaded on to its own carriages, prior to installation on to the carriages,inspect the rollers and the carriages, check grease on the rollers’ axles.

4.3 Lift and lower the transformer using hydraulic jacks in turn: at first one side of the trans-former, then the other one. The transformer should not be inclined for more than 3 %. Do not liftthe transformer from all sides simultaneously. Arrange the hydraulic jacks at places indicated in theoutline drawing. It is forbidden to install the jacks in other places.

4.4 Follow the relevant instructions during unloading the separate packages (bushings, coolingsystem, etc.).




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5 MOVING ON ITS OWN CARRIAGES5.1 Requirements to rail tracks. The tracks should be horizontal (angle 1% max), linear (loss

of linearity in horizontal plane 0,1 % max), displacement of abutting rails in regard to each other in vertical plane 1 mm max, in horizontal plane 2 mm max, gap between abutting rails shall notexceed 5 mm. Type of employed rails should be at least Р 50 and ensure deflection 3 mm maxunder load (at moving).

5.2 Moving procedure. When transformer moving on its own carriages, fix the ropes to spe-cial devices on the tank and move the transformer using electric hoist or tractor with pulley-

block. Moving rate should not exceed 8 m/min. Avoid jerks during moving.The transformers with 4 carriages can be moved in transverse and longitudinal direction,

transformers with more than 4 carriages – along transverse axis of the transformer, by trackswith inclination up to 2%.

When transformer moving by its own carriages start-off force is about 1 kN, moving force –approximately 0,6 kN per 1 t of transformer. Direction of pulling power during rolling should co-incide with the transformer moving direction.

If necessary to change the moving direction, lift the transformer with hydraulic jacks (it. 4.3)to rotate the carriages. In doing so, the roller flanges should be arranged according to outlinedrawing.

6 INSULATION ESTIMATION AFTER TRANSPORTATION6.1 Not later than in 10 days after transformer arrival make the preliminary estimation of its insu-

lation.

6.2 Insulation estimation should be performed by means of the following:- oil sample analysis (bottom residuals) from the transformer tank as for correspondence to the

requirements of Appendix I;-measurement of active part resistance relatively to tank (if measuring lead is available), the

resistance value measured by megger 2500V should be not less than 2 МW, unless othewisespecified in the drawing.

6.3 Draw up the report (act) of insulation state estimation results.6.4 If results are unsatisfactory, contact the Manufacturer.

7 STORAGE7.1. Do not store the transformer in transport state for more than 4 months from the date of

delivery from the Manufacturer, on the assumption of satisfactory results of insulation estimationafter transportation (it.6).

Within storage period, control the transformer tank tightness according to it. 3.5 at least onceper month.

Take measures to minimize storage period of the transformer in transport state.7.2 Long-term storage of the transformer. Install the conservator following the instruction on

conservator. Prior to oil filling of the transformer transported without oil, drain oil residuals. Fill thetransformer with oil completely, prior to do this the tank should be checked for tightness (it. 2.5).Parameters of oil for filling should correspond to the requirements of Appendix A.

Within storage, control oil level in the conservator once per month. Periodically but at least 2times per year, take sample and analyze parameters of oil (breakdown voltage and moisture con-tent) from the transformer tank to check correspondence to Appendix A.

7.3 Long-term storage of components. Apparatus, fasteners, general mechanical rubber goods transported in packing should be stored

on boarding indoors or under the shelter. Storage of individual packages (bushings, cooling systemelements, etc.) should be stored in accordance with their instructions.

7.4 Termination of storage. Based on storage results, draw up the report. In case of failure tocomply storage condition, make integrated assessment of transformer insulation in accordancewith requirements of Appendix I (it. 1) and take the decision as for additional treatment of trans-former insulation.




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8 PREPARATION FOR MOUNTING8.1 Foundation should withstand the loads passed to carriage rollers (single loads).8.2 Area for mounting.Prepare special area for mounting, considering convenience as for arrangement of components,

required equipment and facilities. Equip the area with power supply cabinet of proper capacity,technological vessels for oil, mobile dwelling for duty personnel and storage of tools, instrumentsand materials. Area should be equipped with fire-fighting means, telephone, and illumination, suffi-cient to work during night time.

8.3 Mounting staff. Technological equipment. Documentation.

Mounting and setting-up tests of the transformer should be performed by specialized team of qualified specialists.

Prepare the necessary certified equipment, instruments, tools and materials as for Appendix B. Prior to mounting prepare and render to the mounting organization (team) one copy of the

Manufacturer’s documents as for mounting, reports pertaining to transportation, unloading andstorage of the transformer for the purpose of studying the features and to use them during workperformance.

8.4 Oil.Prepare oil in quantity required for complete filling (topping-up) into the transformer, plus addi-

tional quantity - 5 % of volume – for technological needs. Oil should correspond to the require-ments of Appendix A.

8.5 Calling out of supervising engineer: If supervisor is stipulated in the Contract to supervisemounting works, so, not later than in 10 days before mounting works’ commencement, send invita-

tion of supervisor simultaneously with confirmation of preparedness as for it. 8.1-8.4.8.6 Develop the mounting schedule. Determine scope and sequence of mounting works. Make

up the schedule of mounting works’ execution.8.7 Estimation of insulation condition.Estimate insulation condition following Appendix I. It is permitted to take sample and analysis of

oil from OLTC diverter tank after installation of tap changer pipelines, within mounting works’ exe-cution.

In case of failure to follow storage conditions and unsatisfactory results of oil analyses, it is addi-tionally required to check moisture content of solid insulation models.

Insulation model is installed on the transformer active part and dried during production processup to residual moisture content 0,5 % max. It is purposed for estimation of insulation moisteningwithin the transformer transportation, storage, mounting and operation.

Model consists of electric cardboard samples having different thickness and is to be used at

preliminary estimation of insulation moistening as well as for determination the necessity and per-formance of additional treatment of insulation according to Appendices I and E.

Place of insulation model installation is stated in the transformer operation documents. On thetank, adjacent to the nearest manhole there is an inscription “Insulation model”.

Draw up the report as for obtained results.8.8 Estimation of active part condition.In case of violations during transportation and unloading, it is necessary to inspect active part

inside the tank or perform examination with untanking (or active part lift ing) in scope and sequenceas stated in Appendix D.

8.9 Following the relevant instruction, prepare components, protection and control instrumenta-tion.

Test the detachable bushings 6–35 kV according to Appendix C, if, based on the inspection re-sults, any damage of bushing packing and/or mechanical defects revealed. If no any remarks, testsare omitted.

8.10 Conservator and gas-collecting pipelines. If pipes became unsealed during transportationand storage do as follows:

- seal the conservator, create air or nitrogen pressure 20 kPa, check sealing with soap solutionand wash the internal surface with transformer oil;

- clean the internal surface of gas-collecting pipes, wash them with transformer oil and test thepipelines with pressure 300 kPa during 0,5 h.




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Oil temperature during testing and washing should be min 293 K (20°C), breakdown voltage – 55kV min.

8.11 Cylinders, bushings shields. Prepare the bushing cylinders, bushing shields and other in-sulating parts if they were transported in the separate tank. Check oil used for cylinder and insulat-ing parts transporting. Oil breakdown voltage should be min 55 kV, moisture content 20 g/t max.

If oil does not correspond to the above norms, dry insulating units and parts at temperature95-100°C during 120 hours without vacuum, or during 60 hours at residual pressure 665-1330Pa (5-10 mm Hg).

9 MOUNTING9.1 During mounting of components follow the requirements of the drawings and instruc-

tions. Avoid any “overtightening” during mounting of components. Consider marking. Final tighten-

ing of fasteners should be performed after installation of all branch pipes and compensators.Rubber seals employed for mounting should be free from mechanical damages, cracks and

delaminations.When sealing the joints tighten the fasteners evenly “criss-cross” along the whole perimeter.

When tightening the rubber gasket shrinkage should not exceed 30% of thickness.9.2 In case of tracks for transformer moving on to its operating foundation, it is permitted to per-

form mounting of components at separate mounting area, if unsealing of the transformer required.During transformer moving, follow the requirements of section 5.9.3 Mounting of components not requiring active part unsealing.

9.3.1 Mounting of components (conservator, gas relay, shutoff valve, control and power cables,manometric thermometers, etc.) can be performed both before and after unsealing.

9.3.2 Cooling system mounting is not dependent on the transformer unsealing. Instructions onmounting are provided in Operating Manual of cooling system.

9.3.3 For transformers with flexible envelope, prior to the conservator installation on the trans-former, mount the flexible envelope and release air following operating documents on the conser-vator with flexible envelope.

Perform installation of oil indicators, gas relay and shutoff valve in accordance with relevantdrawings and instructions.

9.3.4 Pockets for sensors of oil and winding temperature indicators, or manometric thermome-ters’ sensors should be filled with transformer oil.

9.4 Mounting of components requiring active part unsealing.9.4.1 Unsealing.

9.4.1.1 Start point of unsealing is the opening any of the plugs providing access of ambient air into the transformer tank, end point is the tank sealing.

9.4.1.2 Depressurisation process should be continuous, and requires such organization of mounting staff as to reduce period of transformer being in unsealed state.

9.4.1.3 Skilled specialists should perform works inside the tank. Personnel cloth must beclean and free of any metal fasteners. In case of pockets on the cloth they should be free of for-eign objects; watches, rings, etc. should be avoided. Do not use adjustable wrenches for workperformance.

Do not step on to insulating parts. Count and check quantity of fasteners, tools and devicesbefore and after works;

9.4.1.4 Within unsealing, take special measures to avoid moistening of the transformer activepart. Insulation protection from moistening should be performed by dried air supplying into thetransformer tank in accordance with the requirements of Appendices G and H.

9.4.1.5 For transformers with active part insulation being totally covered with oil, unsealing of above-oil space during not more than 2 h is permitted without dry air blowing, at relative humidity85% max.




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9.4.2 Transformers 110-330 kV, up to 400 MVA can be depressurised without dry air supplyin to the tank, subject to the following requirements:

- active part temperature for the whole period of depressurisation must be at least 283 K (10°C)and should exceed ambient air temperature for 10°C min - with oil draining, for 5°C min – at un-

sealing without oil draining. If natural ambient conditions do not provide the specified temperature requirement, warm up

the transformer before unsealing. Make measurement active part temperature by thermometer of any type (excluding mercury one) being installed on upper yoke of magnetic core. Active parttemperature of transformers not subjected to heating is determined by oil temperature.

- duration of depressurisation should be 12 h, max – with oil drained, and 20 h, max – at unseal-ing without oil draining.

- retelative humidity of ambient air should not exceed 85%. 9.4.3 Mounting of components of the transformers being partially oil-filled, rated for 220 kV in-

clusive, can be performed without oil draining from the tank below level of winding pressing rings.Full oil draining is required in case of disconnection of leads from the bushings inside the tank,

when active part fasteners requires adjustment, as well as in case of complicated transport condi-tions or non-compliance to storage conditions, when active part and tap changer require inspection(observation).

9.4.4 At mounting of components of the transformers rated for voltage above 220 kV, oil shouldbe completely drained from the transformer.

9.4.5 For transformers shipped without oil, or in case of works requiring oil draining, do asfollows:

9.4.5.1 Remove HV bushing insulating cylinders and their fasteners, if they were shipped inthe transformer tank being in transport state;

9.4.5.2 Remove transport parts and lead fasteners following the drawing requirements of op-erating documents;

9.4.5.3 Make visual inspection of active part, mechanism and electrical contacts of OLTC de-vice. To check OLTC make one commutation cycle manually with drives installed and co-ordinated with selectors. In doing so, check proper operation of mechanism and interferencebetween fixed and moving contacts following OLTC manual.

9.4.5.4 Within bushing installation, it is necessary to observe insulation distances:

- “bushing screen – bushing cylinder”, for bushings 110-230 kV should be min 20 mm, for bushings 400-500 kV – min 30 mm, for bushings 750 kV – min 50 mm;

- “bushing cylinder – winding, insulating barrier” – should be according to operating docu-mentation, if there are no requirements in documentation: for bushings 110-330 kV – min 20mm and for bushings 500 and 750 kV – min 30 mm;

- other insulation distances stated in the.9.4.5.5 Check state and set in operating condition the active part fastening elements in the

transformer tank following the operation documents.9.4.6 At winding leads’ connection, measure insulation distances of flexible joints between them

and other earthed and current-conducting elements, that should correspond to the transformer documents. In doing so, avoid tightness of flexible connections and ensure safety of contact joints. At inspection of insulation distances consider possibility of their shortening at short-circuit condi-tions, deflect the flexible connection to the maximum in the required direction.

9.4.7 Within unsealing period the following should be installed: built-in current transformers,bushings, insulating cylinders of bushings, gas bleeding pipeline and other components included in

the transformer structure and dismantled for transportation period.

9.4.8 On completion of transformer depressurization, the executors should record data of the following checks in the mounting log:- insulation distances stated in technical documentation – actual distances;- proper installation of cylinders and bushings – actual distances;- position of fasteners in active part;- condition of selector of built-in OLTC devices;




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9.5 In case of failure to follow the requirements of it. 9.4.2 as well as Appendices G and H, toestimate the transformer insulation state take cardboard samples and check them as for moisturecontent at the end of unsealing.

9.6 If required, additional treatment of the transformer insulation is to be performed before finaloil filling of the transformer following the requirements of Appendix E.

9.7 After conservator mounting and connection to the transformer, set oil level in the conserva-tor according to oil temperature.

9.8 On completion of mounting works, restore damaged painting coating in accordance with

Appendix F.9.9 Each transformer is shipped with the set of spares for transformer mounting and mainte-

nance within warranty period of operation in accordance with the Manufacturer standard. Oncompletion of mounting, all unused spares are provided to the Customer based on the report(act) with listing the products and the materials.




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10 VACUUM-FREE OIL FILLING AND TOPPING-UP OF TRANSFORMERS10.1 Vacuum-free oil filling and topping up is performed for mounting of the transformers

rated for voltages 110-150 kV, unless otherwise stated in operating documents.10.2 Prior to filling or topping up, install conservator, gas-collecting pipeline and other compo-

nents required for transformer operation. Conservator should be equipped with oil indicator and air breather.

10.3 Make transformer oil filling diagram and connect oil pipeline to shutoff valves at the tankbottom part. It is recommended to install oil treatment plants in the filling diagram for oil supply.Employed oil pipelines should be preliminary cleaned and washed with oil.

10.4 Switch on oil plant (oil treatment plant) and supply oil to the transformer with speed max5 t/h, up to reaching the required oil level in conservator.

Set oil level in conservator by checking marks on the level indicator depending upon trans-former oil temperature.

10.5 Oil filling (topping-up of the transformers equipped with flexible envelope.10.5.1 Install the conservator with mounted flexible envelope on the transformer following the

requirements of relevant instruction.10.5.2 Preliminary fill the conservator up to the level 2/3.10.5.3 Fill (top-up) the transformer up to the level of the tank cover.10.5.4 Assemble pipeline system diagram of the conservator mounting according to the drawing

and fill the transformer with oil from the conservator, in doing so release air from gas relay. Set therequired oil level in the conservator depending on oil temperature in the transformer.

10.6 Open air plugs on the tank and the components and release air remained in closed pock-

ets of the transformer, re-check absence of air in the tank after 12 h oil settling. Perform oil top-ping-up, if oil level is decreased below required one after air release.

10.7 Take oil sample from the transformer tank and analyze it parameters as for correspon-dence to the requirements of Appendix 1.

11 VACUUM OIL FILLING OF TRANSFORMERS11.1 Vacuum oil filling and topping-up of 110-150 kV transformers (if there is reference as for

vacuum filling), with tanks rated for full vacuum, and 220 kV and above, of all types and capacities.11.2 Evacuation scheme of the transformers with attached OLTC devices should ensure main-

taining of the same pressure at both sides of the transition plate to avoid its damage.Directions as for such scheme assembling are given in instructions on tap changer mounting.11.3 Evacuation scheme of the transformers with OLTC devices of immerced type should

ensure maintaining of the same pressure in the transformer tank, the diverter tank, at space

between diverter diaphragm and transport plug, if so stated in OLTC device instruction.11.4 Assembling of evacuation scheme.11.4.1 Install instrument for residual pressure measurement (vacuum gauge) on the tank.11.4.2 Assemble evacuation scheme in accordance with Fig. 1.Connect transformer tank to vacuum pump by vacuum pipeline (internal diameter min 80 mm

and purposed for full vacuum) via a special shutoff fittings at the tank upper part. Install a provi-sional vacuum vessel between the transformer tank and the pump according to Fig. 1.

On the transformer cover it is necessary to install the branch pipe of gas relay with shutoff fit-tings and other components that require tank unsealing.

11.5 Make tightness test of the transformer tank. For this purpose switch on vacuum pump,open shutoff valves of vacuum pipeline and produce residual pressure max 665 Pa in the tank,then close shutoff valves of vacuum pipeline, stop the vacuum pump and record a value of re-sidual pressure in transformer tank. Repeat measurement of residual pressure in the tank in 1

hour after transformer being sealed.Consider transformer sealed, if for that period the residual pressure in the tank has increased

by not more than 665 Pa.Tightness test of the transformers rated for voltage 750 kV is performed at residual pressure in

the tank not exceeding 200 Pa.




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Figure 1 – Evacuation and filling scheme

1 - transformer tank; 2 – shutoff fittings; 3 – instrument for residual pressure measurement;4 - provisional vessel, volume about 0,3 m

3; 5 – vacuum pump; 6 - degassing unit.

11.6 Tank evacuation before oil filling11.6.1 Evacuate the transformer at residual pressure not exceeding 665 Pa within at least 20 h.

Evacuation of the transformers been mounted without oil drain below pressing rings’ level shouldbe performed at residual pressure at least 665 Pa within 2 h min.

11.6.2 Evacuation of the transformers rated for voltage 750 kV should be performed at residualpressure not more than 200 within at least 72 h. At residual pressure 133 Pa and below, durationof evacuation before oil filling can be reduced to 48 h.

11.7 Assembling of filling schemePrepare filling scheme and connect oil duct to shutoff fittings for oil draining at the tank bot-

tom part. Pipelines should be oil-tight, preliminary cleaned and washed with oil. To avoid me-chanical impurities in oil, it is recommended to install sealed filters.

Use degassing plants for oil filling. Special features for filling the transformers with detach-

able OLTC device are stated in specific manuals.11.8 Oil filling.11.8.1 Perform filling with degassed oil having parameters as stated in Appendix A at residual

pressure not exceeding 665 Pa .In doing so, no any speed limitations are applied.Oil filling of the transformers rated for voltage 750 kV should be performed at residual pressure

in the tank not more than 200 Pa.11.8.2 Minimize oil speed feeding, when oil reaches the level 250-300 mm from the cover of the

transformer tank.11.8.3 Continue oil filling of the transformer at residual pressure according to it.11.6 up to oil oc-

currence in oil indicator of provisional vacuum vessel. Disconnect vacuum pipeline.It is permitted to control process of oil topping-up by Допускается осуществлять контроль

процесса доливки по показанию manometric vacuum meter to record pressure in the transformer

tank. In doing so, safety devices to prevent pressure increase in the tank should be in operatingstate.

11.8.4 Assemble pipeline system of conservator mounting following the drawing, and fill thetransformer with oil from the conservator with air release from gas relay. Set the required oil levelin the conservator depending on oil temperature in the transformer.

11.9 Topping and treatment of 150 – 220 kV transformers, if their bushings installed without oildraining should be performed in accordance with it. 11.8.3, 11.8.4.

11.10 Open air plugs on the tank and the components to release residual air.

Р

32

2

1

2

2

4

2

2

5

6




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11.11 Take oil sample and oil testing as for correspondence to the requirements of Appendix A.

When degassed oil sampling take measures to avoid sampled oil contact with air. To follow this

requirement it is recommended to use special sealed oil sampler, syringe, etc.

11.12 Cooling system filling is performed together with the tank, unless otherwise stated in op-erating manual on cooling system.

12 TESTING AND ADJUSTMENT

12.1 Having transformer assembled, check oil tightness.Test the transformers with oil film protection by excessive pressure of dry air 10 kPa.Other transformers are to be tested by creation of excessive pressure of nitrogen or dry air

10 kPa in above-oil space of the conservator.

At testing, oil temperature in the transformer tank should be min 283 K (10°C). Test durationshould be at least 3 h. Disconnect air breather for the period of testing. Consider transformer sealed if there is no leakage observed during visual inspection

12.2 Check oil from the transformer tank as for correspondence to the requirements of Appendix A, and that from OLTC diverter tank – as for correspondence to OLTC manual.

12.3 Measure no-load losses at low voltage using the same circuits as at Manufacturer’s, fre-quency and value of applied voltage should correspond to that stated in the certificate.

Make no-load test prior to commencement of all tests and measurements, before DC supply

to the transformer windings.For three-phase transformer, ratio of phase losses should not differ from that stated in certifi-

cate by more than 5%.For single-phase transformer the losses should not differ by more than 10%.Larger difference are subjected to the agreement with the Manufacturer.12.4 Check OLTC and NLTC devices as for relevant instructions.12.5 Check transformation ratio at all steps of commutation.Measured transformation ratio shall not differ by more than 2% from that calculated by nomi-

nal voltages. For transformers with OLTC the difference between transformation ratios shouldnot exceed values of regulation step.

12.6 Measure DC resistance of windings stated in transformer certificate. For transformers withOLTC and NLTC devices, prior to DC winding resistance make at least 3 cycles of commutationsof tap changer throughout the whole range.

Resistance values of three-phase transformers at the same tapings of different phases at thesame temperature shall not differ between each other by more than 2%. If, due to design fea-tures, the deviation by more than 2% is stated in the certificate, consider deviation value asstated in the certificate.

Measured resistance values of single-phase transformers shall not differ by more than 5%from that stated in the transformer certificate.

12.7 Measure insulation characteristics (R 60 and tg δ ) of transformer and estimate the results inaccordance with Appendix I.

12.8 It is recommended to perform measurement of short-circuit resistance Zк . Measurement of Zк are purposed for obtaining initial values to monitor conditions of the transformer windings withinoperation, after their subjecting to short-circuit current.

12.9 Measure the active part insulation resistance relative to the tank (in case if earthing circuitof active part is led out from the tank). Resistance value, measured by megger 2500V should not

be less than 2 МW, unless otherwise stated in the drawings.12.10 Perform testing and adjustment of cooling system following operating manual on this sys-

tem.




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12.11 Adjust gas protection of the transformer.Functioning of gas relay installed on the transformers with film protection should be checked in

accordance with the manual on gas relay. Functional check by air injection in to the gas relay in-stalled on transformers with film protection is forbidden.

Fill gas relay with oil during slow opening of shutoff fittings at conservator side. In doing so, theplug for gas release from gas relay should be open.

Setting value of gas relay should correspond to the requirements of transformer operatingdocuments. If no statements in documents, setting should correspond to maximum sensitivity,avoiding relay actuation at start and stop of cooling system electric pumps.

12.12 Measure insulation of protection and instrumentation circuits installed on the transformer using voltage 1000V, 50Hz during 1 min, with joints of manometric thermometers being discon-nected. Test insulation of manometric thermometers with voltage 750 V, 50 Hz during 1 min.

12.13 Check built-in current transformers following the relevant instruction.12.14 Prior to transformer trial run under rated voltage, draw up technical report (act) as referred

to the transformer mounting and testing to be signed by representatives of mounting organisation,persons performing testing as well as by manufacturer’s supervisor (if supervision provided).

Report should be in two copies (if supervision is stipulated).

13 TRIAL RUN AND COMMISSIONING

13.1 If more than three months have passed after the last inspection and measuring of insula-tion characteristics, so prior to transformer trial run make the following:

- repeat measurements and checks acc. to it 12.2 and 12.7;- measure DC winding resistance with OLTC and NLTC in operation condition, prior to do

this, make at least three cycles of commutations of tap changer throughout the whole range;13.2 Check readings of all thermometers and correspondence of oil level in conservator to oil

temperature in the transformer tank.13.3 Make sure in opening of shutoff valve, shutoff fittings on oil pipelines of the cooling system

and the gas relay, absence of air in the gas relay. Check correspondence of position indicators of all OLTC and NLTC devices, tank earthing, absence of foreign objects on the transformer and oilleaks. Short-circuit the unused secondary windings of current transformers.

13.4 Check connection to linear bushings and arrester neutral, overvoltage limiters included intransformer protection system according to project.

Unused LV and MV windings of three-phase transformer (autotransformer) should be star or delta connected according to diagram, as required, and protected with valve-type arresters con-

nected between bushings of each phase and the ground. It is permitted to protect unused LVwindings, arranged as the first from the magnetic core, by earthing of one of delta vertex or star neutral.

Do not protect the unused windings if they are constantly connected to at least 30 m cable linewith its enclosure or armor being earthed.

13.5 Check function of all the protections employed. Draw up the test report.13.6 Energise the transformer with protections being actuated for trip. Alarm contacts of the gas

relay should be set to trip. Energise the transformer not earlier than in 12 h since the oil filling (top-ping-up) – for transformers 110-500 kV, and 20 h – for transformers 750 kV.

13.7 Energise the transformer from one of the sides (HV, MV or LV voltage side) at no-load,rated voltage, for the purpose to listen and observe its state at least for 30 min. To listen the trans-formers with ONAF and OFAF, it is permitted to energise them with fans .

Follow operating documents on cooling system and on transformer when energising the cool-ing facilities.

“Push” the transformer several times (3-5 times) to switch it under nominal voltage for thepurpose of checking the protection settings and to avoid magnetising current inrush.

13.8 If trial run and audition results are satisfactory, set the protections to operating position.Then transformer can be energised under load and put into operation.




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13.9 Oil samples should be taken from the transformers energised according to the presentmanual:

- from transformers up to 220 kV inclusive – after energising within 10 days, 1 month and fur-ther as stated in the Manufacturer’s manual on the specific transformer, if no statements – onceper year.

- from transformers 330-750 kV – after energising within 10 days, 1 month, 3 months and fur-ther as stated in the Manufacturer’s manual on the specific transformer, if no statements – onceper year.

Check oil sample according to it.1 – 6 of Table 1 in Appendix A.Contact the Manufacturer if signs of oil quality loss revealed at the initial stage of operation.13.10 Prior to energising, chromatographic analysis should be performed for all the transform-

ers.Further, at the initial stage of operation it is recommended to make chromatographic analysis

of gases dissolved in oil within the following intervals:- in 6 months of operation – for transformers 110 kV, with capacity below 60 MVA;- within the first 3 days, 1 month, 3 months, 6 months of operation – for transformers 110 kV,

60 MVA and above, and for all transformers 220-500 kV;- within the first 3 days, in 2 weeks, 1 month, 3 month, 6 months of operation of transformers

rated for 750 kV.13.11 Draw up the report (act) of the results of measurements and trial run.




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Appendix A(Obligatory)

REQUIREMENTS ON TRANSFORMER OIL1 Fill and top up the transformer with unused oil.2 Parameters of oil for f illing and topping up should correspond to the requirements of Table A1.

Table A1

StandardsName of parameters

Before filling* After filling*

Test meth-ods

1 Breakdown voltage, kV, (min) for trans-

formers rated: up to 500 kV inclusiveover 500-750 kV;over 750 kV

657075

606570 IEC 60156

(IEC 60156)

2 Dielectric loss tangent at 90ºC, %, max,for transformers rated:- up to 750 kV inclusiveover 750kV

0.50.5

0.70.5

IEC 60247

3 Acid number, mg KOH/g, max, for trans-formers rated:up to 500 kV inclusiveover 500 kV

0.020.01 IEC 60296

Norm for oil classISO 2719

I II III4 Flash point, °С, min

140 130 95

5 Water content, % of mass, max,-for transformer with film protection- for transformer without oil film protec-

tion

0.0010.0015

IEC 60814,IEC 60733

6 Mechanical impurities content, purityclass, for transformer :- up to 220 kV inclusive

- свыше 220 kV до 750 kV включительно

16/13

14/12

17/14

15/12

ISO4406

7 Gas content, % of volume, max No norms 1,0 IEC 60567

Norms for oil grade ISO 3016

I II III8 Pour point, °С, min, for transformers, filled

with arctic oil, °С Minus 30 Minus 45 Minus 60

IEC 60422

9 Color and appearancePure oil, free of sediments and

suspended particlesISO 2049,IEC 60296

10 Oxidation stability: According to oil grade IEC 601125

11 Density, kg/dm3

at 20 °С, not more than 0,895ISO 3675,IEC 60296

Norms for oil grade ISO 3104

I II III

12 Kinematic viscosity, mm2/s, max, at tem-

perature:

40 °С

minus 15 °С

minus 30 °С

minus 40 °С

16,5800

--

11-

1800-

3,5--

150

13 Inhibitor content, % of mass0,15 - 0,40 DВРС or DВР IEC 60666

NOTE: *-unless otherwise is specified in operating documents for a specific transformer.




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3 Each oil lot purposed for the transformer filling and topping up should be provided with oilSupplier certificate proving oil correspondence to IEC 60296 requirements.

Oil characteristics supplied with transformer (filled in tank or in separate transport vessels), arechecked as per cl. 1-7 table А1.

4 In case of mixing the transformer oil follow IEC 60296 and IEC 60422.5 Oil from transformers in case of storage above 1 year should be tested in accordance with

items 1,2,5 of Table 1 at least once in 3 months.

6 Oil to be filled into the transformer should be heated up to 318 К (45 °С).7 Before filling oil should be de-gassed using special plant and after this it is recommended

to perform chromatographic and gas-in oil analysis.8 It is allowed to perform testing of oil parameters according to international and national

standards, acting in the country of transformer mounting.




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Appendix B(Recommended)

LIST OF THE MAIN TECHNOLOGICAL EQUIPMENT, INTSTRUMENTS, FITTINGS AND MATE-RIALS FOR TRANSFORMER MOUNTING

№ п/п

Name of equipment

Requirement to equipment

1 Equipment for transformer oil treatment

1.1

Transformer oil treatmentplant(degassingplant)

Production capacity in duty of heating, degassing, drying and filtration 3 m3/h

min,Gas content per volume, max 0,1 %,Water content per mass, max 0,001 % (10 g/t),

Fineness of filtration, max 5 mm,

Max oil temperature at outlet 363 К (90 °С),Oil heater capacity, min 120 kW,Pressure at outlet, min 0.3 МPa (3 kgf/cm2)

1.2

Drying andfiltrationplant (zeoliteplant)

Capacity, m3/h, min:In duty of drying and filtration – 1,2In duty of heating and filtration – 3,6;Water content per mass at outlet per one cycle of treatment, max 0,0005 %of mass (5 g/t);Mechanical impurities per mass per one treatment cycle, max 0,0005 % of mass (5 g/t)

1.3Plant for zeolite re-generation

Capacity by dry air min 100 m3/h,

Dry air temperature at outlet min 673 К (400 °С),

Dew point temperature of dried air max 223 К (minus 50 °С), Dried air pres-sure max 0,08 МPa,Time of regeneration (restoration) of zeolite max 7 h

1.4 Oil heater Capacity min 120 kW

1.5Oil refiningfilter

Fineness of filtration min 5 mm

1.6Centrifugalelectricpump

Capacity min 50 m3/h, pressure at outlet min 80 kPa

1.7 Wheel elec-tric pump

Capacity min 3 m3/h

2 Equipment for transformer vacuum treatment

2.1 Vacuum pumps Capacity min 0,075 m3/s, excessive pressure provided, max 133 Pa

2.2

High-vacuumpump with va-pour freeze-outtrap

Pumping speed of gas-vapor mixture at residual pressure 2,6-60 Pа min0.4 m

3/s,

Residual pressure with inlet branch pipe closed, max2,6 Pa,surface temperature of water vapor condensation measured by coolingmixture temperature, max: refrigerant – solid carbon dioxide and acetone

- 223 К (minus 70 °С),

refrigerant – liquid nitrogen – 113 K (minus 160°С)




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3 Equipment for transformer insulation warm-up and protection from moistening

3.1 Rectifier plant DC at outlet, more than 500 А

3.2 Air drying plant

Dew point temperature of dried air, max 223 К (minus 50 °С), fineness of

filtration max 5 mm,Production capacity as for dry air, min 100 m3/h, pressure at outlet min 30к Pa

4 Equipment for winding compression

4.1 Mounting integratedhydraulic drive

Operating pressure, МPa (kgf/cm2), min:

In low pressure downstream line – 4,In high pressure downstream line – 50

4.2

Hydraulic jacks (4 pcs)with hoses of highpressure (5 pcs) andterminal box

Operating piston diameter 85–130 mm,Technological force created by jack in correspondence with pres-sure in operating liquid 35 Мpa, min 17 tf, hose length, min 10 m

5 Other equipment

5.1Mounting integrated hydraulic drive for lifting thelarge-size products

Operating pressure min 50 МPa (500kgf/cm2),Operating liquid supply 2–5 l/min,Jack load capacity min100 tf,Total load capacity min 400 tf

5.2 Portable lamp with feeding transformer Supply voltage 12 V5.3 Lifting and rigging equipment According to equipment mass

6 Instruments

6.1Instrument set for transformer oil testing

Acc. to IEC 296, IEC 422

6.2 Set of instruments for transformer testing Acc. to IEC 60051

6.3Instrument for measuring water content of insula-tion

Measuring range: 0,5% and over

6.4 Electronic vacuum gauge Measuring range: 1,33-655 Pa

6.5 Manometers, vacuum manometers Measuring range: 655 Pa-0,4 МPa

6.6 Instrument for measuring the dew point of driedair

Measuring range: 203-253 К (minus70 –

minus 20 °С)

6.7 Aspiration psychrometer Measuring range: 5-100 % relative air humidity

6.8 Thermometers Measuring range:

273-573 К (0-300 °С);

183-293 К (minus 90-20 °С)

6.9 Thermal converter of resistance Measuring range: 173-373 К (minus-100

°С)

6.10 Chromel-cupel potentiometer with thermocouples Measuring range: 173-373 К(minus 100-

plus 100 °С)

6.11 Ultrasonic leak tester Sensitivity: At diameter of leak hole above 0,125mm and pressure above 34 kPa (0,34

kgf/cm2)




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7 Fittings

7.1 Seamless steel tubes Dу25 - Dу100

7.2 Metal hose Dу25 - Dу100

7.3 Oil-proof crimped rubber sleeves, diameter 30-80 mm

7.4 Sleeves for gas welding

7.5 Flat tray

7.6 Wooden and plastic ladder

7.7 Sectional ladder for operations on active part inside the transformer tank

7.8 Temporary staging (racks)

7.9 Slings

7.10 Timber sleepers

7.11 Vessel for storage of solid carbon dioxide

7.12 Vessel for liquid nitrogen

7.13 Pads for bushings

7.14 Oil sprayer, collecting drum

7.15 Vessels for transformer oil equipped with moisture protecting system

7.16 Furnace for bottom heating

7.17 Set of bench tools

8 Materials

8.1 Transformer oil for technological needs (5% of oil volume in transformer)

8.2 Oil for vacuum-pump in necessary quantity providing normal operating mode acc. 2.1 dur-ing transformer vacuum treatment

8.3 Vacuum lubrication

8.4 Clean uniform set and boots (for inspection of active part)

8.5 Calico tissues, rag, rubber glue, varnished cloth, solvent, petrol




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Appendix C(recommended)

6 – 35 KV BUSHING TEST CIRCUIT

1- current-carrying pin2- insulator 3- technological tank4- transformer oil5- air release plug

FIG. C1-6-35 KV BUSHING POWER FREQUENCY VOLTAGE TEST, 1 MIN.

Table C.1 – Test voltages of bushings

Bushing voltage class,kV

3 6 10 15 20 24 27 35

Test voltage 24 32 42 55 65 75 80 95

1 Bushing internal part should be fully filled with oil having breakdown voltage not less than 35 kV.2 During bushing filling with oil remove air through air release plug 5.

100m i n

4

3

2

1

5

100 min100 min

3 0 m i n




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Appendix D(Obligatory)

TRANSFORMER INSPECTION WITH LIFTING THE REMOVABLE TANK PART OR THE ACTIVEPART

1 INSPECTION CONDITIONS AND REQUIREMENTS1.1 Perform inspection with lifting the detachable tank part or transformer active part in case

of failure to comply with the requirements of the present manual as well as other violations that

may result in damages inside the transformer.This inspection includes set of works on transformer opening, checking, troubleshooting and

sealing.1.2 Duration and conditions of inspection with tank detachable part or transformer active part

being lifted should correspond to the requirements of section 9 of the present manual.Pay special attention to protect transformer insulation from ingress of dust and other foreign

matters as well as precipitation.It is recommended to perform inspection indoors. Otherwise, provide the tent to close active

part from the top and sides.

2 WORK SCOPE AND SEQUENCE

2.1 Install the transformer by level, check horizontal position of tank frame by the joint.

2.2 Dismantle units and transformer parts if they prevent lifting of active part or removable partof transformer tank.

2.3 During inspection cylinders and screens with cardboard insulation, bushing insulatingtubes should be stored in oil or in sealed package.

2.4 Remove transport fasteners of active part fixing in the tank.2.5 Dismantle drives and insulating shafts of OLTC or NLTC device if they prevent lifting of

active part or detachable tank part.Drives and shafts removed should be marked acc. to phasesDuring inspection OLTC or NLTC drives and shafts should be stored in oil or in sealed pack-

age.

2.6 Check tap fastening Taps (leads) should be disconnected and tied in such manner toprovide lifting of active part or detachable tank part.

2.7 Disconnect active part earthing to the tank and taps of current transformers if they pre-vent lifting.

2.8 Prior to cover or detachable tank part lifting, disconnect fasteners of OLTC device to thetank and lower to active part as stated in operating manual directives.

2.9 Remove cover and lift an active part or dismantle detachable part of the tank. Whencover or detachable tank part unbolting, loose the bolts uniformly along the whole joint perime-ter.

When lifting strictly follow the transformer outline drawing. During lifting observe the gapbetween tank and active part being along the whole perimeter. Do not perform lifting with mis-alignment.

2.10 Active part of transformers with upper joint should be placed on to horizontalwooden pad. Works are forbidden if active part or detachable tank part is in suspended state.

2.11 Provide temporary racks with safety guards to ensure comfortable and safety op-

eration during inspection.Do not rest on to transformer leads, wooden fasteners, windings and insulating parts

during operations with active part.




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2.12 Check tightening of accessible coupling pins and semi-bandages of yokes, leadfasteners, barriers, OLTC and NLTC devices, magnetic shunts of detachable tank part and ac-tive part of transformer. Eliminate looseness.

2.13 Check forces of axial pressing of windings, they should correspond to that stated intransformer operating documents. Adjust the axial pressing force if required. If there is no infor-mation on pressing forces and places of hydraulic jacks installation, contact the transformer manufacturer.

Use hydraulic jacks for checking axial pressing and pre-pressing of windings of trans-formers above 80 MVA.

Axial pressing and pre-pressing of windings of transformers below 80 MVA is adjusted bytorque wrenches.

Adjust axial pressing uniformly by the whole circle. On completion of checking and pre-pressing tighten locknuts of pressing elements.

2.14 Check tightening and tighten the lead joints and locknuts2.15 Inspect insulation of accessible parts of windings, leads, cylinders, bushing installa-

tion and other insulating elements. Eliminate damages revealed.2.16 Check accessible contact surfaces of OLTC device.

2.17 Remove oil residuals from tank bottom. Wash and clean the accessible parts insidethe tank.

2.18 On completion of works on active part, the following should be measured and checked:- Check earthing scheme acc. to drawing;

- measure insulation resistance of all accessible coupling pins and semi-bandages of yokes (in-

cluding vertical yokes of forked magnetic cores) referring to active steel and yoke beams;- measure insulation resistance of pressing rings referring to active steel and yoke beams;- measure yoke beam insulation resistance referring to active steel;- measure electrostatic screen resistance referring to windings and magnetic core. At the

same time check circuit between earthing buses of the screen.Besides the specified earthing diagram, check clearances avoiding short-circuit. If there

is no information in operating documents, the clearances min 10 mm should be provided for transformers above 80 MVA and that min 5 mm – for transformers below 80 MVA.

Measured resistance should be min 2 MΩ, and the resistance of yoke beams referring toactive steel – min 0,5 MΩ.

On completion of measurements specified, restore earthing diagram following operatingdocuments.

2.19 Wash active part with hot jet of dry transformer oil.2.20 Install active part in the tank of transformer with upper joint. Replace the cover or de-

tachable tank part.2.21 Restore active part earthing to the tank.2.22 Install bushings and connect them to the leads Check visually the proper connection.2.23 Make assessment of transformer insulation, perform mounting and oil filling accord-

ing to the requirements of the present manual.2.24 Draw up the report on inspection results.




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Appendix E(Obligatory)

ADDITIONAL TREATMENT (DRYING AND PRE-DRYING) OF TRANSFORMER INSULA-TION

1 Insulation thermo-vacuum treatment of transformer with tanks designed for full vacuum.1.1 Prepare technological equipment, instruments acc. to Fig.E 1, with an exception of vapour

freeze-out trap, following parameters stated in Appendix B. Make technological diagram of insu-lation treatment.

1.2 Prior to pre-drying take electric cardboard specimens from insulation mock-up in thetransformer and set them under the cover, they are to be accessible for sampling.

1.3 Assemble and seal the transformer. Check transformer tightness following cl. 11.5 of thepresent manual.

1.4 Prepare transformer oil, and fill it into transformer. Oil parameters should correspond to Appendix А (with an exception of requirement to gas content).

1.5 Heated up transformer by any method to temperature 353 К (80 °С) during the period asstated in table E.1. In case of negative ambient temperature take measures to warm up thetransformer

Table E.1 – Minimal time of transformer heating up

Transformer voltage and capacity Heating time, h

above 750 kV for all capacities 76220–500 kV and reactor of all capacities 72

220–330 kV, capacity less than 200 МV· А 54110–150 kV, capacity above 400 МV· А 72110–150 kV, capacity (80–400) МV· А 54Below 150 kV, capacity less than 80 МV· А 36

Note – During pre-drying provide continuous oil circulation in the transformer tank.1.6 On disconnection of heating drain oil from the transformer tank under vacuum with simul-

taneous tank filling with nitrogen or dry air.1.7 Make vacuum treatment of transformer at residual pressure max 665 Pa during min 20 h.1.8 Further operations should be in accordance with cl. 3.2 Cold-vacuum treatment of transformer insulation, tanks are designed for full vacuum.

2.1 Pre-drying is effective at insulation temperature not less than 293 К (20 °С) during the

whole drying period. If insulation temperature is lower than 293 К (20 °С), heat the transformer additionally following manual on heating of transformers.

In case of negative ambient temperature take measures to warm up the transformer toavoid moisture condensation inside the transformer and its components.

2.2 Prepare technological equipment, instruments acc. to Fig.E 1, following parameters stated in Appendix B. Make technological scheme of insulation treatment

2.3 Prior to pre-drying take electric cardboard specimens from insulation mock-up in the trans-former and set them under the cover, they are to be accessible for sampling.

2.4 Assemble and seal the transformer. Check transformer tightness following cl. 11.5 of thepresent manual.

2.5 Fill cooler of vapour freeze-out with cooling mixture.2.6 Make in transformer min possible residual pressure and continue vacuum treatment of

transformer.

2.7 Within treatment process it is necessary to carry out the following:- add coolant freeze-out trap maintaining temperature max 203 K (minus 70 °С);- condensate removal and water measuring should be carried out during the first 12 h, further

removal - once per 24 hours (at the same time);- simultaneously with condenser removal it is necessary to check the transformer tightness.Decreasing of leakage value, measured at condenser removal, is evidence of process effec-

tiveness.2.8 During vacuum treatment the following measurements should be performed:




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- residual pressure in transformer - at least once per 2 h;- cooling mixture temperature in cooler – at least once per 2 h, cooling mixture temperature

should be max 203 К (minus 70 °С);- active part temperature by ohmic resistance of HV winding phase B – once per 24 h (at the

same time);- all results should be recorded in the log.2.9 Treatment is to be continued till the moment when:- water escape in cooler should not exceed 0.3 liters per 24 h during last 48 h;- residual pressure in transformer tank should not exceed 26 Pa (0,2 mm Hg).

Fig. E.1-Connecting diagram of equipment for treatment of transformer insulation1- transformer, 2- vacuum manometer, 3- stop valve, 4- electronic vacuum-gauge, 5- vacuum

conductor Ду80-100, 6- vacuum pump of deep discharging with vapour freeze-out trap, 7- vacuumpump of preliminary discharging, 8- oil heater, 9- oil pipeline Ду80-100

2.10 Further works should be in accordance with cl. 3.3 Final works.3.1 Fill transformer with oil up to 200 mm from tank cover in accordance with requirement of

cl. 11 of the present manual.3.2 Create in above-oil space pressure by filling it with dry air with dew point max minus

50°С. Take electric cardboard specimens 0,5; 1,0; 3,0 mm, measure moisture content. Resultsare considered satisfactory ones if moisture content in 1,0 mm specimens is not more than 1 %.

3.3 In case of unsatisfactory results repeat pre-drying.3.4 In case of satisfactory results top up the transformer and oil according to cl.11 of the pre-

sent manual and connect it with conservator.3.5 Draw up the report on pre-drying.4 Drying, washing and regeneration of transformer insulation by hot oil spraying.4.1 Preparatory works.4.1.1 Prepare technological equipment, instruments and materials acc. Appendix B.4.1.2 Prepare transformer oil in quantity as necessary for transformer tank filling up to the

level of upper flanges of bottom yoke beams. Oil should be as stated in cl. 1-5 of table 1 of Ap-pendix A.

4.1.3 Assembling of heating diagram.

4.1.3.1 Assemble outer and inner circuits of heating diagram. Elementary diagram for connec-tion of equipment and instruments is shown in Fig.E.2 (for tanks designed for full vacuum) and inFig.E.3 (for tanks not designed for full vacuum). Assemble sprayers above active part in such away that active part and diverter tank (if available) are washed uniformly. Total length of sprayersdepends upon size of active part. The recommended construction of sprayers and collector isshown in fig. E.4. After drilling remove bars and wash the sprayers with dry transformer oil. Collec-tor for sprayer connection may be arranged as follows: at branch pipe of safety valve installation, at

4

1

9

32

3

6

3

5

87




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flange of inspection manhole and other. The main requirements to collector – total sectional area of inlet branch pipes should be not less than that of outlet branch pipes.

4.1.3.2 Set thermocouples on to active part: one – in magnetic core upper yoke channel(above phase “B” core - in three-phase transformer; over the main core – in single-phase trans-former), the second – in outer sheath of windings, the third – in channel of outer winding (atlower part) of phase “B” (or of the main core).

4.1.3.3 Outer circuit of heating system is to be arranged to minimize the length of oil duct.4.1.3.4 Oil heater should be installed with its upper part below oil level in transformer.4.1.3.5 Oil duct at transformer tank outlet should be equipped with socket for thermometer to

control oil temperature.4.1.3.6 Install electric pumps for oil circulation in heating system and for oil filtration so as to

provide oil “backwater” min 1 m at pump inlet.4.1.3.7 Fill outer circuit of heating system with technological oil with parameters as for table

1, blank-off oil duct at collector side, check tightness by pressure 0,25 МPa during 15 minutes.4.1.3.8 Connect outer circuit to transformer tank.4.1.3.9 Set bottom heating furnaces providing the distance between furnace surface and

transformer tank within being 200 mm.4.1.3.10 Fill the transformer with oil corresponding to the requirements of table 1 up to the level

of upper flange of lower yoke beams.4.1.3.11 Try operation of heating system: direction of electric pump rotation, oil heater func-

tioning, control and protection instruments. It is recommended to make visual inspection of sprayer operation using any of open manholes.

4.1.3.12 Prior to tank sealing take samples of electric cardboard.4.2 Mounting of evacuation system.4.2.1 Mount evacuation system following Fig.E.2 (for tanks designed for full vacuum) or

Fig.E.3 (for tanks designed for partial vacuum). If there is OLTC device, connect transformer tank with diverter above-oil space and with space between membrane and transport plug usingvacuum pipeline, if stated so in OLTC manual. Vacuum treatment diagram for transformers withdetachable tap changers should provide maintaining the same pressure at both sides of reduc-ing plate.

4.2.2 Check tightness of evacuation system be creating air excessive pressure 0,25 МPaand by wetting the welds and seals with soap solution or use ultrasonic leak detector.

4.3 Tightness test of tanks designed for full vacuum.4.3.1 Switch on vacuum plant and create residual pressure in transformer tank max 665 Pa.4.3.2 Switch off vacuum plant and check tightness of transformer tank. Consider the transformer

sealed if increase of residual pressure in the tank does not exceed 665 Pa per 1 hour. If leakagerevealed, eliminate it and repeat checking.

4.4 Tightness test of tanks designed for partial vacuum. Check transformer tank tightness byair excessive pressure 25 kPa. Consider transformer sealed if pressure decrease in the tankdoes not exceed 2 kPa within 3 hours at constant temperature. If leakage revealed, eliminate itand repeat checking.

4.5 Thermal insulation of transformer.Make transformer thermal insulation in two layers:- internal layer – thermal insulating material with glass wool base (or similar);- outer layer – flame-retardant material (under-bottom space inclusive).To avoid thermal insulation wetting due to precipitation, cover the transformer top with water-

proof material.4.6 ACTIVE PART HEATING

4.6.1 Heating of active part of transformer with tank designed for full vacuum.4.6.1.1 Create residual pressure 60– 70 kPa in the transformer tank.4.6.1.2 Switch on oil circulation pump of heating system, turn on oil heater.

4.6.1.3 Heat active part up to magnetic core temperature 353–358 К (80–85 °С) at residual

pressure 60-70 kPa, that of windings – 358–363 К (85-90 °С) (measured by DC winding resis-

tance). Oil temperature at oil heater outlet - 363–368 К (90-95 °С).




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4.6.1.4 Keep the transformer during 48 hours at the temperature reached in accordance with4.6.1.3.

4.6.2 Heating of active part of transformer with tank designed for partial vacuum.4.6.2.1 Create pressure in the transformer tank as designed for the tank.4.6.2.2 Switch on oil circulation pump of heating system, turn on oil heater.

4.6.2.3 Heat active part up to magnetic core temperature 358–363 К (80–90°С), that of wind-

ings – 358–363 К (85-90 °С) (measured by DC winding resistance). Oil temperature at oil heater

outlet - 363–368 К (90-95 °С).4.6.2.4 Keep the transformer during 48 hours at the temperature reached in accordance with

4.6.2.34.6.3 Check operating effectiveness of heating system during the first hours of heating proc-

ess. Evaluation criteria: increase of oil temperature at outlet from oil heater - 278-283 К (5-10

°С) per 1 hour, oil temperature difference between transformer inlet and outlet – max 5 °С.4.6.4 During heating process perform checking and measuring, register the following results in

the log:- magnetic core temperature by thermocouple – each hour -insulation temperature by thermocouple – each hour;- insulation temperature by thermocouple – each hour;- temperature of technological oil at inlet and outlet from the transformer – each hour;- residual pressure in transformer tank – each hour;- parameters of technological oil sample: Ubr, tgδ, moisture content – once per day.4.7 INSULATION TREATMENT

4.7.1 Treatment of transformer with tank designed for full vacuum.4.7.1.1 Insulation is treated by repetitive cycles as follows:-- insulation heating with hot oil spraying up to temperature as stated in cl..4.6.1 (the second

and further cycles – without keeping the time limit 48 hours);- insulation vacuum treatment with circulation being disconnected and at the lowest admissi-

ble residual pressure.4.7.1.2 Coolant should be charged into vapour trap before each cycle of vacuum treatment.

Coolant temperature in vapour trap during evacuation should be max 203 K (minus 70 °С).4.7.1.3 Vacuum treatment of the transformer active part till its temperature decrease up to

343–348 К (70-75 °С) (by DC winding resistance).4.7.1.4 Duration of phases of heating and vacuum treatment within the second and further

cycles is approximately equal, but may be rather different. Make correction of heating and

evacuation duration depending upon actual temperature duty.4.7.2 Treatment of transformer insulation with tank designed for partial vacuum.4.7.2.1 Insulation is treated by repetitive cycles as follows:- insulation heating and washing with hot oil spraying up to temperature as stated in cl.4.6.2 (the

second and further cycles – without time limit 48 hours);- circulation of air-vapour medium at the lowest admissible residual pressure designed for trans-

former tank by simultaneous vacuum treatment of tank and dry air supply.4.7.2.2 Coolant should be charged into freeze-out trap before each cycle of vacuum treat-

ment. Coolant temperature in air-vapour trap during vacuum treatment should be max 203 K (mi-

nus 70 °С).4.7.2.3 Perform circulation of air-vapour medium with evacuation till active part temperature

decrease up to 343–348 К (70-75 °С) (by DC winding resistance).4.8 CHECK MEASUREMENTS DURING TREATMENT.

4.8.1 Measure moisture content of cardboard insulation specimens before and after treatment.4.8.2 Check temperature of active part (insulation, magnetic core, windings) by thermocou-

ples in each hour. Measure temperature of windings by DC resistance on completion of heatingand vacuum treatment (air-vapour circulation) 2 – 3 times.

4.8.3 Check temperature of technological oil at transformer tank inlet and outlet once per each hour.

4.8.4 At the end of vacuum treatment in each cycle, check inleakage in the transformer tankduring 30 min (during drying at deep vacuum only).




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4.8.5 Measure insulation resistance between HV-LV windings (R 60 ) once per 24 h (beforewarming up) at residual pressure 13,3–20 kPa.

4.8.6 Check residual pressure in transformer tank once in hour.

4.8.7 Control moisture content, electric strength and tgd of oil samples from transformer out-

let at reaching oil temperature 333 К (60 °С) – within the first cycle and then, on completion of transformer warming at each cycle.

4.9 COMPLETION OF INSULATION TREATMENT4.9.1 Prior to take the decision on completion of insulation treatment analyze the measuring

results obtained.

4.9.2 Criteria of evaluation to complete treatment of insulation:- stabilization of R60 values at HV-LV section;- reaching of residual pressure in transformer tank min 66 Pa (0,5 mm Hg) (for transformers

designed for full vacuum treatment);- value of water condensate in steam trap should not exceed 0.5 kg per one cycle (within the

last two cycles);- value stabilization of inleakage in transformer tank (at deep vacuum treatment);- oil sample moisture content max 0,001 % of mass (10 g/t);moisture content of 3 mm solid insulation specimens should be max 1,0 %.4.9.3 On completion of insulation treatment proceed with vacuum treatment (air-vapour medium

circulation) till active part being cooled up to the temperature 313-318 К (40-45 °С) (with thermalinsulation dismantled).

4.9.4 Release vacuum and switch on oil electric pump of heating system at active part tem-

perature 313-318 К (40-45 °С) and impregnate insulation with oil during 2 h.4.10 TRANSFORMER DEPRESSURIZATION, HEATING SYSTEM DISMANTLING.4.10.1 Increase the pressure inside the transformer tank up to atmospheric one by dry air sup-

ply in to the tank.4.10.2 Unseal the transformer following the requirements on insulation protection from moisten-

ing.4.10.3 Drain totally oil from the transformer in to the separate vessel. Drain oil residuals

through bottom cocks.4.10.4 Dismantle the sprayers with flexible oil pipelines, thermocouples, fasteners from the tank,

disconnect sprayer collector and remove outer circuit of heating system from the transformer.Mount the components being not installed on the transformer.

4.10.5 Seal the transformer tank, check visually tightening of rubber gaskets. Inspect thetransformer sealing following the requirements of the present manual.

4.10.6 Draw up the report on drying results.




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Fig. E.2 - Connecting diagram of equipment for drying the insulation of transformer with tank de-signed for full vacuum.1 – magnetic core; 2 - transformer windings; 3 - transformer tank; 4 – deep vacuum pump with va-pour freeze-out trap; 5 - electronic vacuum gauge; 6 - vacuum manometer; 7 - vacuum pump of preliminary discharging (evacuation); 8 - air drying plant;

9 – oil heater; 10 – collector; 11 – sprayers; 12 - pipeline Dy80-100;13 – thermometer.

Fig. E.3 - Connecting diagram of equipment for drying the insulation of transformer with tank de-signed for full vacuum.1 – magnetic core; 2 - transformer windings; 3 - transformer tank; 4 – vapour trap;5 – vacuum pump; 6 – vacuum manometer; 7- thermometer; 8- air drying plant;9 – oil heater; 10- collector; 11- sprayers; 12- pipeline Ду80-100.

56

2

4

Level of technological oil

10

8

1

3

11

9

12

12

7

13

22

82

4

Level of technological oil

10

1

3

116

9

12

12

5

7

22




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Fig. E.4 Sketch of oil sprayers and collector

d) sketch of collector (*- Thickness is allowed to be thicker )

Table of sprayer dimensions

Active partlength, м

Pipe number,pcs

а, mm b, mmNumber of

holes per pipeTotal number

of holes

5 10 36 32 120 1200

6 12 44 38 100 12007 14 38 44 88 1232

8 16 41 51 76 1216

9 18 36 58 68 1224

10 20 38 66 60 1200

а в в в в а

Æ 5 0

n holes.Æ2.2

Æ 9 0

Æ 1 0 2

4 holes Æ14а) to be manufactured 2 pcs.

а в в в в а

b) to be manufactured depending on active part length (see Table)

а в в в в а

1000

c) to be manufactured 2 pcs

60

Æ 6 0

15

2 holesÆ4

version1

60

М 5 0

Æ 6 0

Version2

г)способы выполнения соединения между трубами 8 *

hole. Æ 14

Æ12

160*

Æ19

Æ80 4 holes Æ 18

Ду50




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Appendix F(Obligatory)

RECOMMENDATIONS FOR RESTORATION OF DAMAGED PAINT COATS ON METALSTRUCTURES

Restore damaged paint coats occurred during transformer transportation, unloading, storageand mounting in accordance with the following technique:

1 Scratches and strips up to metal.

1.1 Damaged area should be cleaned thoroughly with abrasive paper to remove crumblylayer of paint, oxide film.

1.2 Blow up the surface with compressed air or wipe it with dry cloth.

1.3 Degrease the surface by fabric, moistened in solvent, withstand 20-30 minutes till com-plete evaporation of solvent.

1.4 Using brush, apply two-component primer.For this purpose:- mix primer thoroughly- mix primer with hardener, mark 588.33.99, in proportion 5:1, (service ability of prepared

primer is 8 hours;- apply coat with thickness not less than 80 μm;- dry coating at ambient temperature during 8 hours.1.5 After primer coat become dry, using brush apply two layers of polyurethane enamel PUR

mark 41of the relevant color. For this purpose:- mix enamel thoroughly;- mix enamel with hardener, mark 41.0105, in proportion 3:1(Service ability of prepared enamel – 8hours at temperature 20°C);- apply 2 layers of enamel with thickness of each coat 35-40 μm, (intermediate drying of each layer at temperature 20°C during 24 hours);

2 Materials used:- primer;- hardener for primer;

- enamel;- hardener for enamel.




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Appendix G(Obligatory)

FEATURES OF TRANSFORMER MOUNTING AT NEGATIVE AMBIENT TEMPERATURETo provide the required condition of transformer during works at negative ambient tempera-

ture, take special measures to avoid moisture condensation and freezing inside the transformer and its components, consider the changes of parameters of the materials used, degradation of technological equipment operating reliability, that of accuracy of instruments employed, etc.

1 REQUIREMENTS ON PERFORMANCE OF THE MOST ESSENTIAL MOUNTING-AND- ADJUSTING WORKS

1.1 In case of failure to follow storage conditions of OFAF coolers (unsealing, storage out-doors for more than one year), it is necessary to dry the internal surface with hot air at temperature

min 353 К (80 °С) during at least 5 h, or to open the oil cooler upper and lower covers and checkabsence of ice.

1.2 Perform transformer insulation moisture protection during tank unsealing as follows:

- at ambient temperature up to 263 К (minus 10 °С) - according to cl. 9.4.1.4, 9.4.2 of thepresent manual;

- at ambient temperature from 263 to 253 К (from minus 10 to minus 20 °С), dew point of dry

air supplied to the tank should be max 213 К (minus 60 °С);

- at ambient temperature below 253 К (minus 20 °С), prior to depressurization using dry air,heat the transformer up to the temperature providing the active part temperature at the end of un-

sealing min 273 К (0 °С). In doing so, dew point of dry air should be max 223 К (minus 50 °С). Atthis temperature it is permitted to unseal all the transformers without drying air plant, but with trans-former pre-heating acc. to cl. 9.4.2.

1.3 When mounting the components (insulating cylinders, current transformer installations,OLTC device, HV bushings), in case of abrupt ambient temperature increase (up to positive tem-peratures), take measures to avoid condensation. For this purpose, prior to mounting, preheat thedetachable OLTC devices and insulating cylinders with transformer oil up to positive temperature,and blow through the current-carrying tubes of HV bushings and current transformer installations

with hot air at temperature 353 К (80 °С).Prior to mounting insulation cylinders and bushings installed in oil, wipe their surfaces till dry.1.4 To avoid moisture condensation on internal surfaces of oil-free tank during preheating,

pre-drying and drying, protect the tank with asbestos cloth to provide the positive temperature of the tank top, current transformer installations, gas-collecting tubes, vacuum pipeline of cooling sys-

tem.1.5 When testing and adjustment of transformer equipped with OLTC device change over the

diverter at oil temperature min 248 К (minus 25 °С).1.6 Due to reduction of elasticity of rubber gaskets, tighten them smoothly and uniformly

along the perimeter to avoid cracks in rubber. Prior to installation keep new gaskets in warm placeat least 2 hours, degrease them and dry.

1.7 During pre-assessment of insulation moistening consider the fact that moisture dissolvedin oil becomes suspension and is settled-out during cooling. As a result, in case of satisfactory oilparameters checked during insulation pre-assessment, one could reveal the significant moisturecontent in the transformer. Take special attention when checking the transformer tightness duringpre-assessment of insulation at negative temperature condition.




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Appendix H(Obligatory)

INSULATION MOISTENING PROTECTION DURING TRANSFORMER DEPRESSURIZA-TION

1.Transformer unsealing as for the present technology should be performed at relative hu-midity max 90%, without precipitation and fog. At negative ambient temperature it is necessary tofollow requirements of Appendix G.

2 Prepare air drying plant, instruments for measurement of dry and ambient air parametersas well as materials for closing the transformer manholes.

3 Work order for transformers shipped without oil.3.1 Connect air drying plant to the tank bottom shutoff valves.3.2 Dried air should be supplied in to transformer tank continuously within the whole depres-

surization period. Dew point should not exceed 223 К (minus 50 °С). It should be considered thatthe present technology does not provide full protection of insulation from moistening but signifi-cantly retards moistening process. Therefore, during transformer unsealing follow the below re-quirements:

- Minimize the period of transformer being in unsealed state. Total duration should not ex-ceed 100 hours and unsealing of each of large manholes for current transformers and bushingsshould be max 3 hours;

- Open the manholes and component mounting in turn one by one. Having removed the plug,

close the manhole with clean pile-free material till mounting of the next component. This shouldprotect unsealed tank from direct ingress of ambient air and this is especially important at windyweather;

- Open the manhole for man entering into the transformer tank for the shortest possible time,in doing so, cover it with protecting material to avoid ambient air ingress;

- Do not open the inspection and mounting manholes from opposite tank sides simultane-ously.

3.3 Within unsealing, at the beginning of works and then every 4 hours measure dew point of air at outlet of the plant.

3.4 Upon completion of mounting works or if works should be performed in several stages,make the following operations:

- close and seal all plugs and manholes;- open air release vents, located in the top part of the tank and on the mounted components;

- blow the transformer tank with dry air using the air drying plant, stop blowing at dew point atof air, outgoing from the top shutoff valve on the transformer tank, not exceeding 228 K (45°C);

- close all plugs and shutoff valves on the transformer, produce excessive pressure of dry air within 10-30 kPa (0,1 – 0,3 kgf/cm

2);

- observe air pressure in the tank during transformer storage.Excessive pressure should be not less than 10 kPa.4 Work order for oil fil led transformers.4.1 Connect air drying plant to shutoff valve in the tank upper part.4.2 Drain transformer oil from the tank having simultaneous supply of dry air from air drying

plant.4.3 When further unsealing and component mounting follow cl.3.2-3.4.4.4 Total duration of works as for cl.4.1 and 4.3 should not exceed 100 hours.




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Appendix I(Obligatory)

CONTROL AND EVALUATION OF THE TRANSFORMER INSULATION CONDITION

1 Evaluation of insulation moistening and selection of its restoration method.1.1 Directly after transformer arrival at site it is necessary to establish control over carrying out

the requirements of present instruction as for prevention of transformer insulation moistening dur-ing its storage and mounting period.

Not later than 10 days after arrival, as well as after storage period (prior to commencement of mounting), it is necessary to carry out works on evaluation of insulation moistening degree.

1.2 Transformers transported with the conservator, filled with oil completely:- oil level should be within the limits of the level controlled by oil gauge;- break down voltage of oil in the transformer tank should be min. 55 kV;- tg δ of oil in the transformer tank should not exceed values stated in Table 1, Appendix A;- moisture content of oil in the transformer tank should not exceed 0,0025% - for transformers

110-330kV;- moisture content and break down voltage of oil in diverter tank should meet the requirements

of OLTC operating manual.1.3 Transformers transported without the conservator, filled with oil partially:- above-oil space should be sealed;- break down voltage of oil in the transformer tank should be min. 55 kV;

- tg δ of oil in the transformer tank should not exceed values stated in Table 1, Appendix A;- moisture content of oil in the transformer tank should not exceed 0,0020% - for transformers

500-750kV and 0,0025% - for transformers 110-330kV;- moisture content and break down voltage of oil in diverter tank should meet the requirements

of OLTC operating manual.1.4 For transformers transported without oil, excessive pressure in the transformer tank should

be at least 10 kPa. Break down voltage of oil residuals should be min. 50 kV. Moisture content of oil residuals should be max. 0,0020 % - for transformers 500-750kV and 0,0025% - for transform-ers 110-330kV;

1.5 After mounting of transformer components it is necessary to perform final evaluation of transformer insulation moisture content on the basis of the results of control over carrying out therequirements of present instruction as for prevention of moistening and received results of meas-urements and verifications.

1.6 When absence of violations of stated requirements and positive results of verification, thetransformer can be put into operation without additional treatment of insulation.

1.7 Additional treatment of insulation should be performed in one of the following cases:- failure to follow the requirements of the present instruction as for prevention of transformer

insulation from moistening;-. moisture content of insulation samples of all thicknesses exceed 1 %;- unsatisfactory results of of insulation parameters’ measurement.1.8 Method is selected on the assumption of possible conditions to ensure technology and re-

sults as for required equipment and materials.In case of doubt concerning the selection of insulation treatment method, it is recommended to

contact the transformer Manufacturer.

2 Procedure of measurement and evaluation of insulation parameters.

Measurement of insulation parameters R 60 and tg δ should be performed not less than in 4 hafter filling the transformer and installed conservator with oil, at insulation temperature similar tothat stated in the certificate, with difference ± 5°C, but not lower than 283K (10°С).

In case of necessity, the heating of transformer should be performed..




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If temperature values measured at the Manufacturer are lower than values of ambient air andthe transformer during testing, it is permitted to perform measurements at temperature differenceabove 5°C.

If temperature values of the Manufacturer’s measurements are too high, and as a result of this,further measurements will require additional heating, it is recommended to make measurements of characteristics at temperatures typical for region of the transformer installation. It is purposed toreceive initial data for controlling the transformer insulation condition within operation.

2.2 Measurement of insulation parameters is performed according to the schemes stated inthe transformer certificate.

During measurement, all windings leads of the same voltage are to be interconnected. The re-st windings and the transformer tank should be grounded.

2.3 Temperature of the transformer insulation is assumed as follows:-for transformer without heating, the temperature of top oil;-for transformer subjected to heating, the temperature of HV winding, determined by winding

D.C. resistance. Measurement of above mentioned resistance is carried out not earlier than in 60min after disconnection of winding heating current, or in 30 min after disconnection of externalheating.

Temperature is determined by equation:

( ) ,235235 0 -t Ro

Rx t x

Where: R 0 – winding D.C.resistance measured at the Manufacturer at temperature t 0 , °С

(these values are given in the transformer certificate).R x - measured value of winding D.C. resistance at temperature t x .. 2.4 Insulation resistance is measured by megger rated for 2500 V.Prior to measurement, the tested winding should be grounded for at least 120 s.If uncertain measurement result received (incorrect time countdown, break in power supply

circuit of megger), it is necessary to perform repeated measurement according to the above men-tioned scheme. In doing so, all windings should be preliminary grounded for at least 300 s.

Megger readings are taken in 60 s after applying the voltage to winding insulation.

2.5 R 60 and tg d are to be measured to receive initial data purposed to control the transformer insulation condition within operation and to check absence of its deterioration on completion of mounting works.

Using values R 60 and tg d it is possible to reveal local moistening and pollution of insulatingunits (insulating parts and units of OLTC device, insulation of taps), deterioration of oil condition.

2.6 Evaluation of measurement results is performed by means of their comparison with valuesreceived during manufacturing stage and stated in the transformer certificate.

For comparison, the received values of insulation should be corrected to the conditions of measurement as stated in the certificate.

In doing so, it is necessary to compare the results received at the most similar temperatures.

Recalculation of values R 60 and tg d of insulation to the temperature of certificate measurementis performed by ratios stated in Table 2.

At insulation temperature increase, R 60 is decreased, and tg d is increased.

2.7 Recalculation of values tg d of insulation taking into account influence of oil is performed byequation:

tg d Ф= tg d ИЗ – К (tg d М 2 - tg d М 1 ), (2)

where tg d Ф – is actual value of insulation tg d (taking into account influence of oil);

tg d ИЗ – measured and corrected to certificate temperature value tg d of insulation;

tg d М1 – is tg d value of oil filled at the Manufacturer, corrected to the temperature of measure-ment of insulation parameters by means of factor К 3 according to Table 3;

tg d М 2 – tg d value of oil filled during mounting, corrected to temperature of measurement of in-sulation parameters by means of factor К 3 according to Table 3;

К – correction factor depending on design features of the transformer, approximated to thevalue 0,45.




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Received values of insulation tg d , corrected to certificate temperature of measurement and con-

sidering influence of oil tg d l, should not differ for more than 50 % as for deterioration.

Values of insulation tg d , corrected to certificate temperature, equal or less than 1%, should beconsidered as satisfactory without comparing with certificate values.

2.8 Insulation resistance R 60 , measured during mounting and corrected to temperature of certifi-cate measurement should be at least 50 % from value stated in the transformer certificate.

2.9 In some cases, by agreement with the Manufacturer, insulation R 60 and tg d difference for more than 50 % is permitted, if compared with values stated in the transformer certificate, under the stipulation that this difference can be explained by influence of another type of oil, method of

heating, or other reasons not concerned with dangerous moistening.In this case, it is necessary to check moisture content of insulation samples installed in the

transformer, to determine actual value of insulation tg d taking into account the influence of oil tg d .The results with all initial data should be informed to the Manufacturer.

Decision as for necessity of additional treatment of insulation or putting transformer into opera-tion is to be taken at the Manufacturer on the basis of comprehensive analysis of received resultsof values of insulation parameters, moisture content of samples as well as conditions of transporta-tion, storage and mounting.

3 Example of correction of R 60 and tg d values measured at mounting against the certificate val-ues.

3.1 Value of insulation tg d , measured during mounting at temperature 295 K (22°С), makes up1,1 %.

Value of insulation tg d , measured at the Manufacturer at temperature 25 °С and stated in trans-former certificate (acc. to the same measurement scheme), is 0,95 %.

Measurement temperature difference:

Dt =25 – 22 = 3 °.Conversion rate acc. to Table К 1 = 1,09.

Value of insulation tg d , corrected to temperature 298 K (25°С) (from the certificate)

tg d П = tg d · К 1, (3)

tg d П = 1,1 · 1,09 = 1,2 %

Corrected value of insulation tg d against certificate data is:

tg d П =95.0

1002.1 ·= 126 % .

3.2 Value of insulation tg d , measured during mounting at temperature 289 K (25 °С) made up1,2 %.

Value of insulation tg d , measured at the Manufacturer at temperature 295 K (20°С) and statedin the transformer certificate (acc. to the same measurement scheme), is 0,9 %.

Measurement temperature difference:

Dt =25 – 22 = 3 °.Conversion rate acc.to Table 3: К 1 = 1,09.

Value of insulation tg d , corrected to temperature 295 K (22 °С) (from the certificate).

tg d П = tgδ/K1 (4)

tg d П = 1.2/1,09 = 1,1%

Corrected value of insulation tg d п against the certificate data is:

tg d п =

9.0

1001.1 ·= 122 %.

4 Example of calculation of actual value of insulation tg d , tg d Ф.

Value of insulation tg d , measured during mounting and corrected to insulation parameter meas-

urement temperature 295 K (22 °С):

tg d ИЗ = 1,1 %

Value of oil tg d l, measured at the Manufacturer (from the certificate) at 363 K (90°С)

tgdМ1 = 0,5 %.




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Value of oil tg d , measured during mounting at 363 K (90°С):

tg d М 2 = 2,2 %.

Correction of certificate value of oil tg d to the temperature of measurement of insulation pa-

rameters 295 K (22°С)

tg d M1 = tgδ/K3 (5)where К 3 – is determined acc.to Table 3. For differential temperature:

Dt = 363 K (90) – 295 (22) = 68K, К 3 = 15,92

tg d М 1 = 0,5/15,92 = 0,031 %

Correction of mounting value of oil tg d to the temperature of measurement of insulation parame-

ters 295 K (22°С)

tg d М 2 = tg d М 2 /K 3 (6)where К3 – is determined acc.to Table 3. For differential temperature:

Dt = 363 (90) – 295 (22) = 68 °, К 3 = 15,92

tg d М 2 =92.15

2.2= 0,13 %

Determination of actual value of insulation tg d :

tg d Ф= tg d ИЗ – К (tg d М 2 - tg d М 1 ) (7)

tg d Ф = 1,1 – 0,45 (0,13 – 0,031) = 1,06 %

5 Examples of correcting the insulation value R 60 to the temperature of measurement statedin certificate:

5.1 Value R 60 , measured during mounting at temperature 295 K (22°С), is 510 МW.

Value R 60, measured at the Manufacturer at temperature 298 K (25°С) and stated in the certifi-

cate (acc. to the same measurement scheme), is 530 МW.Difference in temperature of measurement

Dt = 298 (25) – 295 (22) = 3° Conversion rate acc. to Table 2: К 2 = 1,13.

Value R 60, corrected to temperature 298 (25 °С) (from the certificate)R 60 П = R60/R3 (8)

R 60 П = 510/1,13 = 450 МW Corrected value R 60 П against the certificate value is

R 60 П = 530

100450 ·

= 85 % against certificate value;

5.2 Value R 60 , measured during mounting at temperature 289 K (25°С), is 530 МW.

Value R 60 , measured at the Manufacturer at temperature 295 K (22°С) and stated in certificate

(acc. to the same measurement scheme), is 450 МW.Difference in temperature of measurement

Dt = 298 (25) – 295 (22) = 3 °.Conversion rate К 2 = 1,13.

Value R 60 , corrected to temperature 295 K (22°С) (from the certificate)

R 60 П = R 60 2 К ·

R 60 П = 13,1530 · = 600 МW

Corrected value R 60П against the certificate value is

R 60 П =450

100600 ·= 133 %.




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Table 2 – Values of conversion rates for R 60 and tg d of insulation

Differential temperature ( Dt ), оС

Name of pa-rameter

1 2 3 4 5 6 7 10 15 20 25 30

К 1 ( tg d ,)

1,03 1,06 1,09 1,12 1,15 1,18 1,21 1,31 1,51 1,75 2,00 2,30

К 2 (R 60 ), 1,04 1,08 1,13 1,17 1,22 1,28 1,34 1,50 1,84 2,25 2,75 3,40

Table 2.3 – Values of conversion rates for tg d of oil

Differential temperature (Dt ), оС Name of pa-

rameter 1 2 3 4 5 10 20 30 40 50 60 70 80

К 3 ( tg d of oil)

1,04 1,08 1,13 1,17 1,22 1,50 2,25 3,40 5,10 7,50 11,2 17,0 25,5




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intruction manual of 500kv pt in dung quoc subs

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