E P S YEarthfault Protection System

Electronic-Components

2

Introduction

to the operators of medium-voltage networks. This is notavailable using the traditionalmethods and devices.

The electronic components ofthe new earthfault protectionsystem (EPSY) and their configu-rations are summarized asfollows.

devices for the recognition anddetection of earthfaults. Devicesand systems of traditional earth-fault protection engineering donot meet or only meet theserequirements in a limited way.

The protection system EPSYessentially consists of a contin-uously adjustable arc sup-pression coil combined with anautomatic compensation con-trol device and a selective,highly sensitive earthfaultdetection device. In particular,the newly developed method forselective detection of high-impe-dance earthfaults, which isintegrated in EPSY, offers thepossiblity of early fault detection

EPSY (Earthfault Protection Sys-tem) is a new and comprehensi-ve earthfault protection systemdesigned for compensatednetworks. As compared to othermethods of neutral pointtreatment, earthfault compen-sation shows clear advantagesin ensuring both the safety ofpersonnel and supply as well aslimiting possible consequentialdamages during an earthfault.

In comparison with lowimpedance neutral pointgrounding, the reduction of thefault currents during earthfaultcompensation places high requi-rements on the reliability and theselectivity of the protection

Fig. 1 Front view EFC30

Earthfault Compensation Controller EFC30

The controller EFC30, available since 1991, determines the resonance point using a short detuning of theASC-coil. Remarks: For details see page 9 and EFC30/EFC40 brochure.

Basic Units

3

For determination of theresonance point, the new method of the earthfault com-pensation controller EFC40 usesthe current injection into thezero-phase sequence system andtherefore detuning of the arcsuppression coil is not necessary.

The EFC40 calculates the zero-sequence impedance by measuringthe vectors of both the neutral-to-ground voltage and thecurrent injected into the zero-sequence system of the network(according to the EDF licence)before and during the injection.

If the network is very symmetric,the neutral to ground voltage isextremely low and there is nomarked resonance curve whichcould be used as a control criterion.In this case it is possible to increasethe neutral-to-ground voltage,by using a permanent injectionof a current into the zero sequencenetwork, so that changes of thenetwork configuration lead to areliable trigger of the EFC40controller. Furthermore, theEFC40 is able to tune on-loadadjustable step-coils s.

Remarks:

• The operation mode of theEFC40 necessarily requires theinstallation of the currentinjecting device ECI.

• Without the current injectingdevice ECI, the EFC40 can beused in the EFC30 operationmode.

• For details see page 9 and theEFC30/EFC40 brochure.

Fig. 2 Front view EFC40

Earthfault Compensation Controller EFC40

4

Earth Fault DetectionSystem EFD

The core of the electronic part ofEPSY is the earth fault detectiondevice EFD, which is used bothin the separate earthfault detec-tion device EFD10 and in the com-bined control and detection unitEFD40 (compact device). Thedifference in the new earth faultdetection method compared toprevious relay methods availableis that the measuring signals ofthe zero-sequence currents areperiodically recorded and combi-ned in a central unit for furtherprocessing. The zero-sequenceadmittances of the feeders (ad-mittance method) are determi-ned by the vectorial measure-ment of the zero- sequencecurrents (Iol .... Ion) and of thezero-sequence voltage (Uo) befo-re and during a defined modifi-cation of the zero-sequence sy-stem. The modifica-tion of thezero-sequence system is causedby a current injection, i.e., withthe assistance of the current in-jection, in the healthy network,the EFD system determines thereference values of admittanceagainst earth and their naturalasymmetry per feeder by vecto-rial measurement of Uo and Io.

After this initial phase, a checkwithout current injection is madeperiodically to identify the feederin which the asymmetry chan-ges.The calculations of this chan-ge are made by using the vec-torial measurements of the ac-tual values of Uo and Io andtheir reference values recordedduring the initial phase. The feederindicating the greatest change ofasymmetry is recognized as thefaulty feeder. Using this methodit is possible to detect high-ohmic faults up to 100 kOhm.This selectivity and sensitivity cannot be achieved by using any de-vice or system of the traditionalearth fault protection technique.

Fundamentals inthe Detection of theFaulty Feeder

If an earth fault appears in a net-work, it leads to a steady-stateasymmetry of the network afterthe decay of the transient pro-cesses. The zero-sequence voltage(Uo) as well as the zero-sequencecurrents of all feeders which aresupplied by the same busbar( Iol .... Ion ) are available asmeasurement variables for thedetection of the feeder in whichthe earth fault occurs. In thecase of an earthfault, the highestzero-sequence current does notflow in the faulty feeder but inthe one that has the highest lineto earth capacitance. Thus theamplitude of the zero-sequencecurrent cannot be used as a crite-rion for detecting the faulty fee-der. Traditional earthfault detec-tion relays have problems toachieve a reliable and selectivedetection of low and high impe-dance earthfaults. This is due toa combination of the measure-ment principles used, the effectsof instrument transformer errorsand implications of fault evalua-tion in a single relay mode.

Earthfault Detection Device EFD10

5

EFD10-Types(for details see page 9):• EFD10-8 (Earth fault detection

device for a maximum of8 feeders)

• EFD10-16 (Earth fault detectiondevice for a maximum of16 feeders)

Remarks:• If there are more than 16

feeders, the expansion unitEFX10 is required.

• The EFD requires theinstallation of the current in-jecting device ECI.

Fig. 3 Front view EFD10-16

6

Compact Device EFD40(Earth Fault Compensation Controller and Detection)

Fig. 4 Front view EFD40-16

The compact device EFD40combines all the functions of theearth fault compensationcontroller EFC40 and the earthfault detection device EFD10.

EFD40-Types(for details see page 9):

• EFD40-8 (earth fault controllerand detection device for amaximum of 8 feeders)

• EFD40-16 EFD40-16 (earth faultcontroller and detection devicefor a maximum of 16 feeders)

Remarks:

• If there are more than 16feeders, the expansion unitEFX10 is required.

• The EFD necessarily requiresthe installation of the currentinjecting device ECI.

7

Expansion Unit EFX10

Fig. 5 Front view EFX10

In case it is necessary to monitormore than 16 feeders in onesubstation, the devices EFD10and EFD40 have to be extendedwith one expansion unit EFX10.

In addition, the expansion unitEFX10 can be used to increasethe number of the digital inputs/outputs which are required, forexample, for the replica of theswitching state of the circuit-breakers in multiple bus-baroperation.

EFX10-Types(for details see page 9):

• EFX10-8 (earth fault detectionexpansion unit for 8 additionalfeeders)

• EFX10-16 (earth fault detectionexpansion unit for 16 additionalfeeders)

8

The current injection device ECIis used to change the zero-sequence voltage by injecting acurrent into the zero-sequencesystem. This change of the zero-sequence voltage is requiredboth for the earth fault compen-sation controller EFC40 (seepage 3) and for the earth faultdetection device EFD (see page 4).

Current Injection Device ECI

ECI - Technical Data

Voltage supplyvoltage 230 V AC, 50 Hzcurrent 7 A at healthy network condition

max. 23 A in case of an earth faultinrush current approx. 140 A

Control contactsvoltage range 24...240 V AC oder V DCcurrent max. 40 mApower consumption max. 2 W

Output to the ASCinjection voltage 230 V AC, 50 Hzinjection current approx. 7 A (max. 23 A))

Output to the controllercurrent transformer 1 Apotential-free signal contacts 5 A / 250 V AC

Dimensionswidth / height /depth 640 / 800 / 250 mmmass approx. 75 kg

The current injection into thezero-phase sequence system isusually done on the low-voltageside via a secondary auxiliarywinding and a sufficient dimen-sioned voltage winding of thearc suppression coil.

The current injection device ECIessentially consists of a transform-er, capacitors for current-limiting,relays, control- and signalcontacts.

9

Technical Data for Basic Devices

EFC

30

EFC

40

EFD

10-8

EFD

10-1

6

EFD

40-8

EFD

40-1

6

EFX

10-8

EFX

10-1

6

Basic Device Controller Detection Controller & ExpansionDetection

Data

HardwareCPU: 32 bit Transputer (RISC Prozessor)with floating point unit

x x x x x x x x

ROM 1 MB 2 MB 2 MB 2 MB 2 MB 2 MB 2 MB 2MBRAM 1 MB 8 MB 8 MB 8 MB 8 MB 8 MB 4 MB 4 MBDisplay: double supertwist LCD 640 x 200 Pixelwith back-light

x x x x x x

Film designed keyboard x x x x x xPower supply: 110-220 V DC, 230 V AC, 50 Hz, 50 WOptional: 24, 48, 60 V DC

x x x x x x x x

Analogue inputs for voltage (amplitude):3 mV...230 V AC

1

Analogue inputs for voltage (amplitude and phase):3 mV...110 V AC

4 4 4 4 4

Analogue inputs for current injection (ECI):0...1 A AC

4 4 4 4 4

Analogue inputs for zero-sequence currents:0...1 A AC oder 0...5 A AC

8 16 8 16 8 16

Analogue input for coil position:linear potentiometer 0...200 Ω bis 0...2 kΩ 1 1 1 1or current imput 0...20 mAAnalogue output (for Uo, coil position, distance location):0...20 mA, programmable

2 2 2 2 2 2

Digital inputs: potential free contacts24...250 V AC od. DC

16 32 32 32 32 16 16

Digital inputs: potential free contacts24 V DC, 60 mA

4

Digital inputs: potential free contacts24...250 V AC od. DC

2

Digital autputs: potential free change over contactsmax: 250 V AC 1000 VA or 250 V DC 100 W

4 8 8 8 8 4 4

Digital autputs: potential free make contactsmax: 250 V AC 1000 VA or 250 V DC 100 W

7 12 24 24 24 24 12 12

Serial Interface: 3 x RS232 opt. opt. opt. opt. opt. opt.Expansion with controller possible x xExpansion with detection possible x xUpgradeable for up to 24 feeders x x x xReplica of the substation´s switching condition by means of groups x x x x x xReplica of the substation´s switching board x x x x x x100 V AC reference voltage necessary x x x x xSoftwareControl operation by tuning of the ASC x x x xControl operation by means of current injection x x xControl operation at very low neutral-to-ground volt. x x xDetection of high- and low-ohmic earth faults x x x x x xDual bus bar operation possible opt. x x x x x x xSCADA system (SPABus, IEC/VDEW 6) opt. opt. opt. opt. opt. opt.Mechanical DataMass in kg 8,2 13,5 18,0 19,5 18,0 19,5 15,5 18,0Height of the 19“ rack in HE 3 6 6 6 6 6 6 6

W 483 483 483 483 483 483 483 483Dimension in mm H 132,5 266 266 266 266 266 266 266

D 252 300 300 300 300 300 300 300Case opt. opt. opt. opt. opt. opt. opt. opt.

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Summary of the Electronic-Componentsof EPSY (incl. Options)

EFC30 Basic device, earth fault compensation controller EFC30EFD10-UD-8 EFC30-upgrade with the detection EFD10 for 8 feedersEFD10-UD-16 EFC30-upgrade with the detection EFD10 for 16 feeders

EFC30-SIF Serial interface optionEFC30-AKL Terminal strip optionEFC30-WAND Wall-mounting optionEFC30-ADAPT EZR2-adapterEFC30-DC Optional power supply voltageEFC30-GEH Protective case for the EFC30EFC30-HB Additional user manualEFC30-SW-FIX Optional software for fixed coil controlEFC30-SW-RC* Optional software for resistor controlEFC30-SW-KN Optional software for KNOSPE resistor controlEFC30-SW-LS Optional software for control by external power switchEFC30-SW-MR Optional software for more than one controller in the same networkEFC30-SW-UM Optional software for control at U>UmaxEFC30-SW-ZS* Optional software for time synchronisation by means of impulse input EFC30-SW-U Optional software with special functions for large U0EFC30-SW-LT Optional software for SCADA

EFC40 Basic device earth fault compensation controller EFC40EFD40-UD-8 EFC40-upgrade by the detection for 8 feeders in the basic deviceEFD40-UD-16 EFC40-upgrade by the detection for 16 feeders in the basic device

EFD10-8 Basic device for earth fault detection EFD10 for 8 feedersEFD10-16 Basic device for earth fault detection EFD10 for 16 feedersEFD40-UC EFD10-upgrade by the controller EFC40 in the basic device

EFD40-8 Compact device for 8 feeders, including controller and detectionEFD40-16 Compact device for 16 feeders, including controller and detection

EFD40-GEH Protective case for EFC40, EFD10 and EFD40EFD40-SIF Serial interface option for EFC40, EFD10 and EFD40EFD40-SW-LT Optional software for SCADAEFD40-SW-STU Optional software for control of a step adjustable ASCEFD40-SW-AWE Optional software for automatic reclosing function

EFX10-8 Expansion device for additional 8 feedersEFX10-16 Expansion device for additional 16 feeders

EFX10-0 Expansion unit (empty)EFX10-UD-8 EFX10 plug-in modul for additional 8 feedersEFX10-UD-DI EFX10 plug-in modul for additional 16 digital inputsEFX10-UD-DO EFX10 plug-in modul for additional 16 digital outputs

ECI-FL Current injection device (outdoor construction type)ECI-IR Current injection device (indoor construction type)

EFD-EdC Detuning capacitor for polygon-method (fault distance location) incl. software

Remark: For detailed information about hard- and software-options please inquire and see thecorresponding user manual.* These software options are also available in the EFC40 operation mode.

11

Examples for Upgrading Basic Devices

Upgrading of the controller EFC30 by the earth fault detection:

requested 8 Feeder 16 Feeder 24 Feederconfig. EFC30 EFC30 EFC30

EFD10-8 EFD10-16 EFD10-16actual EFX10-8config.EFC30 EFD10-UD-8 EFD10-UD-16 EFD10-UD-16

EFX10-8

Upgrading of the controller EFC40 by the earth fault detection:

requested 8 Feeder 16 Feeder 24 Feederconfig. EFD40-8 EFD40-16 EFD40-16

EFX10-8actualconfig.EFC40 EFD40-UD-8 EFD40-UD-16 EFD40-UD-16

EFX10-8

Upgrading of the earthfault detection EFD10 by additional feeders resp. by the controll function:

requested detection detection, controlconfig. 24 Feeder 16 Feeder

EFD10-16 EFD40-16actual EFX10-8config.EFD10-16 EFX10-8 EFD40-UC

Upgrading of the compact device EFD40-16 by additional feeders:

requested 24 Feederconfig. EFD40-16

EFX10-8actualconfig.EFD40-16 EFX10-8

.... Necessary units for the upgrade

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Examples of System Configurations

Fig. 6 EFC30 in a one-busbar configuration

Fig. 7 EFC40 in a one-busbar configuration

13

Fig. 8 EFC40 in a two-busbar configuration

Fig. 9 EFD10 in a one-busbar configuration

14

Fig. 10 EFD10 in a two-busbar configuration

Fig. 11 Control and detection with EFD40 in a one-busbar configuration

15

Fig. 12 Control and detection with EFD40 in a two-busbar configuration with one tuneable and one fixed arc suppression coil

Fig. 13 Control and detection with EFD40 in a two-busbar configuration with two tuneable arc suppression coils

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E 665Subject to change without notice (05.2006)Printed in Canada.