THE PROVEN POWER.

Earth-Fault Compensation ControllerEFC60m

THE PROVEN POWER.

In resonant grounded power distribu on networksthe neutral point of the network is connected to earthby means of a stepless adjustable inductor. If the res-onance circuit formed by the adjustable induc ve coiland the earth capacitance of the network is tuned toor close to resonance, the fault current is greatly re-duced in case of a line-to-earth fault (earth fault). Inmost cases the arc caused by the fault current is ex n-guished without the need to switch o the faulty partof the network.

As the Arc Suppression Coil (ASC) and the earth capac-itance form a resonance circuit, the neutral-to-groundvoltage of the network depends on the value of theinductance of the ASC and reaches a maximum whenthe ASC is tuned to resonance. The ASC can be tunedautoma cally by evalua on of the voltage maximumof the resonance curve (by coil adjustment) or by im-pedance-measurement of the resonance circuit (bycurrent injec on).

Due to the growing share of cables the networks todayn akre net-w h-e onso l togr eaut n-t em s-sa

Since the mul -frequency current injec on enablesnetwork analysis with frequencies, di erent from theopera ng frequency, the EFC60m proves to be a com-pact new control device, which is extremely resistant tonetwork interferences.

Determining the resonance peak byMul -Frequency Current-Injec onBy means of a thyristor the 50 (60) Hz injec on cur-rent can be pulsed quickly. This generates side bandsaround the 50 (60) Hz main frequency. The evalua onof the side frequencies makes this method immune tonetwork interferences.

Fig. 1: pulsed 50 Hz injec on current

Fig. 2: generated frequency spectrum

In addi on, by evalua ng at least two frequencies, acalcula on of the total capacitance or inductance ofthe zero sequence system can be performed, takinginto account possibly exis ng xed coils or decentralcoils.

Application Control Algoritm

Due to the growing share of cables today networksbecome more symmetric, so that the peak resonancevoltage, which is caused by the natural network asymmetry, consequently decreases. On the oth-er hand, interferences, e.g. caused by load fluctua onsor decentral genera on, increase. The neutral toground voltage, which is the only control criteria for the automa c controller therefore looses its quality. Con-trol problems probably lead to excessive stress on the mechanism of the ASC and / or to annoying error mes-sages.

3THE PROVEN POWER.

Determining the resonance peakby 50 (60) Hz - Current-Injec on

It is possible to calculate the resonance curve by in-jec ng a current at fundamental frequency into thezero sequence system of the network and to measurethe vectors of both the neutral-to-ground voltage andthe injected current. It is therefore not required tochange the coil posi on. This protects the adjustmentmechanism in case of uctua ng neutral to groundvoltage against too frequent use.Where a network is essen ally symmetrical and theneutral-to-ground voltage extremely low, it is possibleto increase the neutral-to-ground voltage by using thecurrent injec on permanently so that changes of thenetwork con gura on provide a reliable signal for thecontroller (inverse opera on mode).

Fig. 3: Current injec on into zero sequence system

The fundamental frequency injec on can be ac vat-ed alterna vely to the mul -frequency method, if theneutral to ground voltage is su ciently stable.

Vo neutral to ground voltageECI current injec on deviceL inductance of Petersen coilIpos coil posi on (stated in Ampere)Ro equivalent resistance, represen ng lossesC capacitance of network versus groundIo zero sequence current (mostly capaci ve)Iu unbalance currentEu equivalent voltage for unbalance currentZu asymmetry impedance of network

Determining the resonance peak byminor coil movement

During a tuning opera on the ASC is adjusted by asmall amount. Measuring the coil-posi on as well asthe neutral-to-ground voltage during the adjustmentopera on, the controller computes the detuning factorv, the asymmetry factor k and the damping factor d,which determine the resonance curve of the neutral-to-ground voltage. Taking into considera on a custom-er se able under- or overcompensa on, the controllercalculates the necessary posi on and directlyadjusts the ASC to the calculated value. In order toachieve a high tuning accuracy, the controller movesthe coil beyond the resonance point, if allowed to doso (Vo <Vmax). This is par cularly necessary for smalldisplacement voltages and voltage uctua ons due tointerference e ects.

Fig. 4: control with coil adjustment

In the EFC60m this method may be used as a backup,

e.g. in the event of current injec on failures.

Important network parameter :

v = Ipos—Ires / Ires [%] detuning factorIv = Ipos—Ires [A] detuning currentIpos [A] coil posi onIres [A] resonance posi on of networkd = Id / Ires [%] damping factorId [A] = Vo/Ro damping (residual) currentk = Zu * jwC [%] asymmetry factor

4THE PROVEN POWER.

Hardware Op ons

Alterna ve power supply

Addi onal external digital inputs

Addi onal external digital outputs

IEC 61850 Ed2 module (externally mounted)

Assembly variant on moun ng plate

Assembly variant in electrical cabinet ( outdoordesign for moun ng at the coil—controller andcoil already wired and prepared)

Variant without current injec on (tuning with coiladjustment)

Addi onal parallel inductance L2 in order to in-crease the injected current (L2 externally mount-ed)

Design features EFC60m

Hardware

Microprocessor based controller 19“ -rack mount-ed (3 RU), width 84 HP with integrated currentinjec on.

Op mized opera on by means of a graphic 7“LCD touchscreen.

Extended opera on via PC by means of a terminalprogram E-So

Indica on of the digital outputs via customer la-belled and parameterized LEDs at the front

Central acquisi on and display of arc suppression coilalarms via LEDs at the front

USB A and B at the front

Analogue output modules 0...20 mA for externalindica on of coil posi on and neutral to groundvoltage.

Fig. 5: EFC60m

5THE PROVEN POWER.

Opera on

Easy opera on by means of an integrated 7“ Colour-Touchscreen. This display can principally be installed

Easy adap on to individual network condi ons by exi-ble parameterisa on and changeable pre – set factoryvalues.

remotely from the controller, if a communica onover Ethernet is possible.

Fig. 6 Resonance curve display at controller and E-So

Terminal program E-So for Microso Windows forparameter se ng and on-site opera on via PC as wellas for remote control over Ethernet .

Fig. 7 Parameter tree in E-So

Fig. 8 E-So C-Interpreter for internal PLC-commands

6THE PROVEN POWER.

So ware

easy parameter se ng, since pre-set factory val-ues can be adjusted by the user as required.

high exibility through so ware controlled inputsand outputs, free assignment of digital outputs todi erent state func ons as well as free assignmentof digital inputs to di erent control func ons.

powerful PLC—in case special func ons are re-quired a powerful PLC is available, which can beprogrammed with the help of a C-interpreter.

indica on of opera ng status via a short text mes-sage

coun ng of various events (e.g. transient earthfault) and controller condi ons for sta s cal eval-ua ons. Data-Download via USB or Ethernet inter-face (RJ45) onto PC or directly to a USB—s ck.

remote parameter changes by means of a PC con-nected via USB or Ethernet.

several parameter levels for adap ve user se ngs

So ware-Update by USB or Ethernet interface(RJ45) from PC or directly from a USB—s ck.

So ware Op ons

several controllers within the same networkreliable control without mutual in uence, no re-mote connec on necessary

external circuit breakeradjus ng the ASC to a prede ned value when theASC is switched o

resistor controlautoma c resistor control at earthfault

x coil controlautoma c switching on/o of the xed coil

control at earthfaultcontrol back to ideal compensa on (v=0) if anearth fault occurs

SCADASPABusIEC 60870-5-101/103/104IEC 61850 Ed2 (with op onal external hardwaremodule)

automa c switch Vo>Vmaxautoma c switching of a damping resistor duringsearch opera on if V exceeds Vmax

vectorial triggerConsidera on of amount and phase angle of Vo astrigger criterion.

7THE PROVEN POWER.

Technical Data EFC60m

Standard operating7'' LCD, 800 x 480 pixels (WVGA), Touchscreen,16 LEDs 1

Front16 LEDsUSB-AUSB-B for SCADA, PC or modem

111

BackUSB-A on the backsideRS485, 3 pole connectorRJ12 (via converter connector) RS232 for SCADA modemRJ45 for SCADA or PC

2211

Analog voltage Input10 mV ... 230 V AC 50 Hz, rated burden < 0,5 VA 5

Analog current Input0 A … 5 A / AC 50 Hz 4

Analog current Outputfor e.g. Vo, coil position 0 ... 20 mA/DC, maximum burden at 20 mA/DC: 800 Ohm 3

Coil positionLinear potentiometer, 0 ... 200 Ohm or 0 ... 2 kOhm or 0 ... 20 mA/DC - input signal 1

Digital Inputs4x potential free input 24 ...... 230V AC/DC (aBE)15x potential free inputs insulated in groups of terminals 110 … 230V AC/DC (BE)(Optional 15x potential free inputs 24-110V DC are mandatory if power supply 80-130V DCis used)

19

Digital Outputspotential free changeover contact (normal open, normal closed) 230 V AC/DCmax 5 A continuous, max making capacity 1000 VA, max breaking capacity 30 VA(1x EFC, 2x E-REL)

3

Digital Outputspotential free contact insulated in groups of terminals (normal open) 230 V AC/DCmax 5 A continuous, max making capacity 1000 VA,max breaking capacity 30 VA (5x EFC, 10x E-REL)

15

Power supplyStandard: 120 - 300V DC 110-230V ACOptional: 80 – 130 DC!!!!(Observe polarity – internal fuse blows in case of wrong connection)Power consumption max. 20W

1

Maximum permissible overvoltage at the voltage inputs 230V AC continuous (2 x Un for 1s)Maximum permissible over current at the current inputs (1,2 x In continuous, 100 x In for 1s)

Hardware component Amount

8THE PROVEN POWER.

C60m

Mechanical DataDimensions EFC60m Rack

Width 483.0 mmHeight 133 mmDepth 388 mm (incl. handles)cut-out for front moun ng : Width 450 mm, Height 134 mmnecessary gap below and above : min. 1 HU (44 mm)

Weight 18 kg

Temperatures Opera on 0°C... +40°C

Storage -25°C... +55°C

Transport -25°C... +70°C

Max. installa on al tude O2000m. a.m.s.l.

Humidity (24 h average) from 5% to 95% acc. IEC 60255-1

Protec on class IP20

Fig. 9: EFC60m—dimensionsFig. 9: EFC60m—dimensions

Mechanical Data EFC60m

9THE PROVEN POWER.

Multi-Frequency Current-Injection

The Current Injec on Device ECI is used to producedi eren al measurement values by means of a cur-rent injec on into the zero-sequence system. Theinjec on components are integrated inside the EF-C60m 19“ rack and connected to the control unit.Where a network is essen ally symmetrical the

The current is injected into the zero sequence system via asuitably rated power auxiliary winding of the arc suppres-sion coil. The current injec on device essen ally consists ofa current limi ng inductance, thyristor and a control unit.

neutral-to-ground voltage is extremely low and nospeci c resonance curve is available. In such case theneutral to ground voltage can be increased by perma-nent current injec on, so that network changes willreliably lead to a trigger of the tuning procedure.(Inverse mode with 50 Hz permanent current injec-

on).

A residual current device (RCD) must not be used inthe 230 V AC power supply, because there is no gal-vanic separa on between current injec on device andthe grounded power auxiliary winding.

Fig. 10 Inverse mode of current injec on

Fig. 11 Mul -frequency current-injec on

10THE PROVEN POWER.

Fig. 12 EFC60m wiring diagram—standard / page 1

11THE PROVEN POWER.

Fig. 13 EFC60m wiring diagram—standard / page 2

12THE PROVEN POWER.

Fig. 14 EFC60m wiring diagram—standard / page 3

13THE PROVEN POWER.

The Trench Group is your partner of choice for electrical power transmission and distribution solutions today andfor the development of your new technology solutions of tomorrow.

For more information check out our website at www.trench-group.com

or send an e-mail to sales@trench-group.com

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E 657 08.08

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