type lfcb digital current differential relay
TRANSCRIPT
Type LFCBDigital Current Differential Relay
2
Type LFCBDigital Current Differential Relay
Features• Unit protection for two and three
terminal feeders
• Phase segregated differentialcurrent protection with highsensitivity
• Single and three pole tripping
• Suitable for use with dedicatedoptical fibre links or multiplexedsystems
• Optional dual redundantcommunication channels for twoterminal feeders
• Continuous channel propagationdelay measurement andcompensation
• 1 to 11/2 cycle operating timewhen used with a standard 56 or64kb/s channel
• Power-on diagnostic andcontinuous self-monitoring
• Event recording, fault recordingand intertripping
• Remote interrogation via RS232serial link
Models AvailableThree models are available:
LFCB102 – for two terminalapplications
LFCB103 – for three terminalapplications
LFCB202 – for two terminalapplications, with dualredundantcommunicationchannels
Introduced in July 1993, there arethree versions of the LFCB whichhave the facility to provideprotection where the line is fed fromtwo circuit breakers, as often foundin 11/2 switch substations or meshcorner applications. This protectionof the line between the CircuitBreakers (when closed) and LineIsolator (when open) ensures thatonly the local relay operates forfaults in this area. Normal currentdifferential protection is carried outwhen the Line Isolator is closed.
These versions are:
LFCB122 – for two terminalapplications
LFCB123 – for three terminalapplications
LFCB222 – for two terminalapplications, with dualredundantcommunicationchannels
A range of communicationinterfaces is available to allow theLFCB to work with different types ofdedicated or multiplexedcommunications links.
ApplicationCurrent differential protectionrequires a comparison of thecurrents entering and leaving aprotected zone.A dependable communicationfacility is needed to allowinformation exchange betweenrelays at different line ends so thateach can compare the local currentswith the currents at the remote ends.
The digital current differential relay,type LFCB, offers phase selective,true differential protection for twoand three terminal transmission andsub-transmission lines. The relay isan all digital, microprocessor based
Figure 1: Operator interface
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design for use with modern digitalcommunication systems. Since datacan easily be mixed and carriedwithin a digital data message, allthree phase current signals aretransmitted over the samecommunication channel.Currents are compared on a perphase basis, obviating the biasingproblem of the conventionalsummation current trans-formerapproach and providing phaseselection information for single poletripping and to identify the faulttype. Relays at all ends operatesimultaneously providing rapidfault clearance irrespective ofwhether the fault current is fed fromall terminals or from only one lineend.
Intertripping commands and statusinformation are also carried withinthe data message to provideauxiliary intertripping facilities andother information.
An LFCB102 version is availablewith segregated phase directintertripping.
The LFCB202 relay providesredundancy of communication bytransmitting and receivingmessages over two communicationchannels. Both channels aremonitored continuously by therelay. If one of the channels hasfailed, communication between therelays can still be maintained bythe other healthy channel.The LFCB202 is applicable to twoterminal lines only.
The LFCB does not include harmonicrestraint against transformermagnetising in-rush currents and sois not suitable for circuits whichhave power transformers within theprotected zone.
DescriptionThe relay is housed in a 4U(178mm) high case suitable foreither rack or panel mounting.The relay has a modularconstruction using plug-in moduleswhich are individually tested andcalibrated in the factory.If necessary, modules can beexchanged without any need torecalibrate the relay.
The analogue inputs from maincurrent transformers (1A or 5A) arescaled down by very low burden(<0.1VA) relay current transformersand then converted into digital databy a 12 bit analogue to digitalconverter. External plant status andcontrol signals are received via optoisolated inputs in the same module.The analogue and status inputs aresampled at a rate of 8 samples percycle.
A 16 bit microprocessor module isused to control data acquisition,process protection and controlalgorithms, and to control the outputand communication modules.It contains read-only memory (ROM)for programmes, non volatile read/write memory (EEPROM) for settingsand operation records and read/
write memory (RAM) for temporarydata.
An RS232 serial communicationfacility is also provided which canbe used to interrogate the relayeither locally or remotely.
A high performance communicationmodule provides two independentduplex channels for signallingbetween relays. These are based onthe high level data link controlprotocol (HDLC). The channels arecapable of operating at up to1Mb/s but are normally set tooperate at 56 or 64kb/s.The module incorporates its ownmicroprocessor to handle the highspeed data communication and toprocess part of the protection andsignalling functions.
Two output relay modules, eachcontaining eight hinged armaturerelays, provide twenty six trip andalarm contacts.
A power supply module convertspower from a dc supply to internalvoltage rails. A power failuremonitoring circuit with alarm outputcontact is included. The relayconsumes less than 10W in thequiescent state and less than 20Wunder tripping conditions.
The front panel operator interface,shown in Figure 1, consists of a 2row by 16 character alphanumericliquid crystal display (LCD) togetherwith a seven pushbutton keypad.With the cover in position only the‘ACCEPT/READ’ key, for reading
Figure 2: Block diagram
Currentinputt
A/Dconverter
Opto-Isolators Microcomputer
DC – DCconverter
Auxiliaryrelay
outputs
Communication
Operatorinterface
Ia, Ib, Ic
Plant andprotectioncontacts
Auxiliarydc supply
+6.5V+19.5V–19.5V+24V
Digitalcommunicationlink to remoterelays
Trip and alarms
LCD displayand keypadLED indicationsserial andparallel I/O
4
A number of methods can be usedto synchronise data sampling ofrelays at different ends. Most of themethods however require anexternal clock reference andcomplex clock generation andcontrol circuitry.The LFCB uses a novel softwarecontrolled ‘poll and answer’technique which has been devisedto provide a means of continuouslymonitoring and measuring thepropagation delay of thecommunication channels during theprocess of obtaining current vectorinformation from remote ends.The technique assumes equalchannel propagation delay for thedata transmit and receive paths.No synchronisation is required fordata sampling at the different lineends as the process of polling vectorinformation also includesmeasurement of the time deviationof data sampling between line ends.A software technique is then used totime align current vectors fromdifferent line ends to a common timeframe before the differential andbias currents are calculated.
and accepting alarms, and readingthe relay settings, and the ‘RESET’key, for clearing alarms, areaccessible.
Other information available fordisplay includes phase, differentialand bias current magnitudes at localand remote ends, fault and alarmrecords, communication errorstatistics and setting values.They are selected for display usingthe five pushbuttons arranged in acruciform pattern, four of these actas cursor keys for selectingcommands or altering parameters ina menu fashion.The ‘SET’ key at the centre is used toconfirm new settings and othersecurity related commands.
The relay has four indicating lampsand two 25 pin D type socketsmounted on its front panel.One socket is used for local RS232serial communication whilst theother is a parallel input/output portwhich functions either as a parallelprinter port or as a test port forconnection to computer basedinjection testing equipment.
OperationAn LFCB current differentialprotection system consists ofidentical relay units located at eachend of the protected line. In contrastto conventional analogue relays, thethree phase currents at each lineend are measured by sampling at afixed frequency. The data samplesrepresent the instantaneous valuesof the current waveforms and maycontain dc offset, harmonics andhigh frequency components. It isdesirable therefore to filter andpreprocess the data to a formsuitable for the calculation of themagnitudes of differential and biascurrents. This is achieved by digitalfiltering using the One Cycle Fourierfiltering technique which yields thepower frequency components of thecurrent waveforms in vector form.The vector values of all three phasestogether with other relevant timingand status information aretransmitted over the communicationchannels to the other ends of theline. Based on the local andreceived vector information, thedifferential currents and biascurrents of all three phases can becalculated and compared on a perphase basis to make the trippingdecision.
When vector samples from eachend are compared, they mustcorrespond to the same samplinginstant to prevent an erroneousdifferential current being measured.Unless the sampling times aresynchronised at each end, it isnecessary for the vector samples tobe time aligned to compensate forthe different sampling instants andthe channel propagation delay fordata to be sent from one end toanother.
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Figure 3: External connection diagram: type LFCB digital current differential relay with fibre optic communications interface.
A25
A26
A
B
C
A
B
C
P2 P1
(See Note 2)
Protected Zone
TX
RX
TX
RX
A21
A22
A23
A24
H13
H14
A5
A6
A7
A8
A9
A10
A11
A12
A3
A4
A1
A2
F17
F19 Trip A (1)94A–1
F18
F20 Trip A (2)94A–2
G17
G19 Trip A (3)94A–3
G18
G20 Trip A (4)94A–4
F21
F23 Trip B (1)94B–1
F22
F24 Trip B (2)94B–2
G21
G23 Trip B (3)94B–3
G22
G24 Trip B (4)94B–4
F25
F27 Trip C (1)94C–1
F26
F28 Trip C (2)94C–2
G25
G27 Trip C (3)94C–3
G26
G28 Trip C (4)94C–4
F13
F15 Any trip (1)94–1
F14
F16 Any trip (2)94–2
G13
G15 Block autoreclose (1)
96–1
G14
G16 Block autoreclose (2)
96–2
F9
F11 Intertrip (1)85–1
F10
F12 Intertrip (2)85–2
G9
G11 Intertrip (3)85–3
G10
G12 Intertrip (4)85–4
F1
F3 Protection operated A94D(A)–1
F594D(A)–2Spare
F2
F4 Protection operated B94D(B)–1
F694D(B)–2Spare
F7
F8 Protection operated (C)94D(C)–1
G7
G8Communicationsupervision alarm
97Z–1
G2
G4 Protection schemeinoperative alarm
97X–1
G697X–2Spare
G1
G3Relay inoperative alarm(see Notes 3 & 4)
97Y–2
G5
Spare
97Y–1
H5
H6 Power supply failurealarm (see Note 3)
97W–1
Phase rotation
A
BC
SeeNote 7
SeeNote 6
LFCB103Digital current
differential relay
DC supplyVX(1)
Inhibittrip/alarm
outputs
Reconfigurationinterlock (Note 6)
Initiatepermissive
intertrip
Initiateintertrip
Resetindicationand alarm
Time sync
CH1
CH2
Fibre opticcommunication
(see Note 5)
Case earth
Opto-inputAuxiliary
supplyVX(2)
S1S2
5. Optical connectors are of SMA 9mm typeunless otherwise specified.
6. The block auto-reclose contacts can beselected to close on permissive intertrip orto close on permissive intertrip and 3 phasefault trip.
7. The trip A, trip B and trip C contacts close forany trip conditions if three pole tripping modeis selected.
Notes
1. (a) CT shorting links makebefore (b) and (c) disconnect.
(b) Short terminals break before (c). (c) Long terminals.
2. Earthing connections are typical only.
3. All outputs are shown de-energised. Underhealthy operating conditions the output isenergised. The following conditions willcause the contacts to reset:
B. Loss of internal dc rail voltage.A. Loss of dc supply.
Failure detected by micro computer duringrun-time self monitoring.
4. The following conditions will also cause thecontacts to reset:A. Failure detected by micro computer during
power-on diagnostics.B.
C. Loss of internal clock pulse signals.
D. Operation of internal watchdog circuit.
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Bias RestraintCharacteristicThe relay has a dual slopepercentage bias restraintcharacteristic as shown in Figure 4.The initial bias slope ensuressensitivity to low level faults. As thefault level rises, extra errors may beintroduced as a result of currenttransformer saturation and the biasslope is therefore increased tocompensate for this.
Power-on Diagnosticsand Continuous Self-MonitoringPower-on diagnostic tests arecarried out automatically by therelay when it is switched on.These tests include checks on thetimer, microprocessor, memory andother major components. There arealso a number of system checkswhich continuously monitor theoperation of the relay.
In the event of a failure detected bythe power-on diagnostic or self-monitoring tests, an error messageis displayed on the front panel LCDand the ‘relay inoperative alarm’output contact closes. The relay willthen either lock out or attempt arecovery depending on the type offailure detected.
Event and FaultRecordingThe relay keeps a record of the lastten alarms/events which are storedin non-volatile EEPROM memoryand these are preserved, even incase of a power loss. Each eventrecord gives the cause of the eventand the time and date of itsoccurrence.
The relay also records the last threefault records in non-volatile EEPROMmemory. Each fault record containsinformation on the fault type and themagnitudes of the local, remote,differential and bias currents of thethree phases and time and date ofthe operation of the relay.
Print FacilitySettings and recorded informationstored in the relay can be printedout via the parallel port or the serialport on the front panel.Each printout contains the userdefined relay identification and timeand date of printing.
Remote Interrogation viaRS232 Serial LinkA 25 pin D type socket is alsoprovided at the rear of the relay toallow an operator to communicatewith the relay via the serial portusing a visual display unit (VDU) orpersonal computer. The facilityemulates the front panel keypad andLCD and allows access to the
Test FacilitiesTest facilities are provided to enablethe relay to be thoroughly testedduring commissioning, routinemaintenance and fault findingoperations. One test facility is the25 way parallel socket on the frontpanel which allows the internalvoltage rails and the states of thetrip and block auto-reclose outputsof the relay to be checked whilst therelay is in service. The socket alsohas input lines which can be used toemulate keystrokes on the frontpanel, facilitating the use ofcomputer based secondary injectiontest sets to interact with the relayand issue operator commands foroutputting data or changingsettings. This reduces line outageduring routine testing.
A number of tests are availablethrough the operator interface.A measurement function is providedwhich displays local and remotephase and sequence componentcurrents on the LCD. This can beused to check the analogue inputhardware and software, also currenttransformer polarity andconnections. Test options areprovided to display the on/off statesof the opto-isolated status inputs andto perform a lamp test on the fourrelay indicating lamps.
Further test options enable the relaytrip and alarm outputs and theirassociated circuits to be tested.
Figure 4: Bias restraint characteristic
0.5 ( Ia + Ib + Ic )
Ia Ib
Ic
IS1
IS2
Trip
Percentagebias k1
Percentagebias k2
No trip
Bias currentIbias
Differentialcurrent
IdiffIdiff
Ibias
Ia + Ib + Ic=
=
The relay operates when
(1) For IS2Ibias+ IS1Idiff Ibiask1
(2) For IS2Ibias– (k2 – k1) IS2 + IS1Idiff Ibiask2
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Figure 5: Direct intertrip
command menu. Given a suitableserial communication link theoperator can interrogate the relayremotely and ask for print-outs offault and alarm records and otherinformation. It is also possible tochange settings, if the relay hasbeen set up to allow full remoteaccess.
Intertrip FacilityThis is an auxiliary signalling facilitywhereby when the ‘initiate intertrip’opto isolator is activated, the relaysets a corresponding status bit in itstransmit message to command theremote relays to close their intertripoutput contacts (85-1 to 85-4).It may be assigned by the user toany trip or signalling function suchas direct transfer trip or to blockauto-reclose.
Figure 6: Permissive intertrip
Permissive IntertripFacilityThe permissive intertrip facility isprovided to intertrip circuit breakersat the remote ends. The ‘initiatepermissive intertrip’ opto-isolatedinput may, for example, beconnected to an output contact of abusbar relay to intertrip remotebreakers upon a busbar fault.When the ‘Initiate permissiveintertrip’ input is activated, the relaysets a corresponding status bit in itstransmit message.This commands the remote relays tocheck if the current flowing into theinitiating end exceeds the currentthreshold setting IS1 and if so, to tripafter the permissive intertrip timesetting is exceeded. The permissiveintertrip time delay allows time forthe fault to be cleared by circuitbreakers at the initiating end. This issimilar to a conventional interlocked
overcurrent scheme except that theovercurrent check is done at theremote ends and no additionalrelays are needed.The permissive intertrip shares thetrip output contacts of the currentdifferential protection function butalways trips three phase.
The relay provides two outputcontacts for blocking auto-reclose onpermissive intertrip. These contactsmay also be selected to block auto-reclose on three phase faults.
Relay A Relay B Transformerprotection
DTT = 1
Data messageOpto
Relay A Relay B Busbarrelay
PIT = 1
Data messageOpto
IBF
8
Figure 7: Reconfiguration
For operational reasons it may benecessary to switch out one of theline ends, and its associated relay,on a three terminal circuit. A secondreconfiguration feature is providedwith the LFCB103 by which, after allsecurity checks are satisfied, anoperator at one end can commandthe two remote relays to work as atwo terminal system. The local relaycan then be switched off leaving thenow two terminal line to beprotected by the two remote relays.A restore command can similarly beissued to bring the system back tothree terminal operation.
Relay A Relay B
Opto
3 2
Relay C
3 2
Three to Two TerminalReconfiguration(LFCB103 or LFCB123only)The LFCB103 relay is normally usedfor the protection of three terminallines. The relay can, however, be setfor two terminal operation.This allows the relay to be appliedto a two terminal line which may beconverted to a three terminal line ata later date. Since only a settingchange is required to configure therelay for two or three terminaloperation, no hardware or wiringchanges are required when the thirdterminal is added. Additionalsecurity interlocks are incorporatedin the setting procedure to provideadded security when changing therelay configuration.
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CommunicationInterfacingTo ensure compatibility with a widerange of communication equipmentand media the LFCB is designed towork within the signallingbandwidth of a basic 56/64kb/spulse code modulated (PCM)channel.
Several options are available forinterfacing the LFCB to acommunications link. The link can
be either dedicated to the currentdifferential protection signalling ormultiplexed and shared with otherprotection and telecommunicationequipment, employing optical fibresor conventional media (see Figure8). The modular design of the LFCBmeans only the communicationinterface module need be varied tosuit different requirements. The basicinterface options are describedbelow.
Figure 8: Communications arrangements
Dedicated Optical LinkDifferent ranges of communicationdistance require different types ofoptical transmitting and receivingdevices. The LFCB has three basicversions of optical communicationinterface, all of which operate with50/125µm multimode fibres at the850nm wavelength and use SMA9mm type optical connectors.
The basic short range 850nminterface has an optical budget of0–14dB. Medium and long range850nm interfaces are alsoavailable.
Details of versions suitable fordedicated 1300nm or 1550nmwavelength applications areavailable upon request.The 1300nm interface can bespecified for use on either multimode or single mode optical fibre.The 1500nm interface can only beused with single mode fibre.All 1300nm and 1500nm interfacesare available with ST or FC/PC styleoptical connectors.
Multiplexed Link-OpticalCables Connecting Relayand MultiplexerWhen using multiplexers, the LFCBrelay should contain the short range850nm optical interface (seesection: Dedicated Optical Link fordetails).An MITZ interface is required at themultiplexer end for optical/electricalsignal conversions. One MITZ unit isrequired per communicationschannel per relay. All MITZ units usethe same type of optical transmitterand receiver as the LFCB shortrange 850nm optical interface.
MITZ versionsThe MITZ 01 interface unit supportsG.703 co-directional interfacing.
The MITZ 02 interface unit supportsV.35 interfacing.
The MITZ 03 interface unit supportsX.21 interfacing. This unit may alsosupport subsets of RS449.Please contact ALSTOM T&DProtection & Control Ltd for anyfurther information.
Note: The co-directional G.703,V.35 and X.21 interfaces complywith CCITT recommendations.
LFCBPCMMUX
Multiplexed link – relay connected to a remote PCM multiplexerusing optical fibres and via an MITZ interface unit
(b)
Optical fibresMITZ
Electricalconnections Multiplexed
link
Other protection andtelecommunication
equipment
LFCBLFCB
Optical fibres
(a) Direct link using optical fibres
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Technical Data
Ratings
Current (In) 1A or 5A(4 x In continuous)(100In or 400A or 1s)
Frequency Nominal Operative Range50Hz 47 to 51Hz60Hz 56.4 to 61.2Hz
Auxiliary voltage Vx(1) (DC) Nominal Operative Range(Relay power supply) 24/27V 19.2 – 32.4V
30/34V 24 – 40.8V48/54V 38.4 – 64.8V110/125V 88 – 150V220/250V 176 – 300V
Auxiliary voltage Vx(2) (DC) Nominal Operative Range(Opto-isolator supply) 24/34V 19.2 – 40.8V
48/54V 38.4 – 64.8V110/125V 88 – 150V220/250V 176 – 300V
Note: Vx(2) may be differentfrom Vx(1)
Characteristic See Figure 4
Settings
Basic differential current (IS1) 0.2 to 2In in 0.05 stepsThreshold for increase bias (IS2) 1 to 30In in 0.05 steps
Bias k1 (Ibias < IS2) 30% to 150% in 5% steps
Bias k2 (Ibias > IS2) 30% to 150% in 5% steps
Accuracy Better than ±10% under referenceconditions.The effective accuracy range is upto 30In.
Accuracy is unaffected by dc supplyor ambient temperature variationswithin their operative ranges.
Operating time Frequency Minimum Typical50Hz 18ms 22 – 30ms60Hz 16ms 19 – 25ms
Reset time 59ms max (50Hz)
52ms max (60Hz)
Note: The trip contacts remainclosed for a minimum of 60ms.
Returning ratio 75%
Note: This is the differential currentat which the relay resets, divided bythe differential current at which therelay operates.
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Contact rating
Make and carry for 0.2s 7500VA (30A or 300V ac or dcmaxima)
Carry continuously 5A ac or dcBreak (104 operations) AC 1250VA
DC 50W resistive 5A or 300V25W inductive, maximaL/R=40ms
Durability
Loaded contact 10,000 operations minimum
Unloaded contact 100,000 operations minimum
Burdens
AC <0.1VA
DC (Vx(1)) 10W quiescent: 20W tripping
DC (Vx(2)) Maximum 0.3W mean burdenper input.
Calendar clock Based on an internal free runningcrystal oscillator. Accuracy is within±2s per day.
The clock can be synchronised to anexternal source at either 5, 10, 15,30 or 60 minute intervals.
Intertrip
Operating time 20 – 25ms typical (50Hz)18 – 22ms typical (60Hz)
Reset time 25ms max (50Hz)21ms max (60Hz)
Note: The intertrip contacts remainclosed for a minimum of 60ms.
Permissive intertrip
Time delay setting 0 – 200ms in 5ms steps
Operating time after delaysetting 22 – 27ms typical (50Hz)
19 – 23ms typical (60Hz)
Reset time 26ms max (50Hz)24ms max (60Hz)
Note: The trip contacts remainclosed for a minimum of 60ms.
Current transformer requirements
BS3938 Class X For applications where themaximum value of secondarythrough fault current x primarysystem X/R is less than 120In, then:
for IS2 = 2In; k1 = 30%; k2 = 100%Vk>95In (RCT + 2RL)
for IS2 = 2In; k1 = 30%; k2 = 150%Vk>65In (RCT + 2RL); X/R <40
Vk>75In (RCT + 2RL); X/R <70
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For applications where themaximum value of secondarythrough fault current x primarysystem X/R is less than 350In, then:
for IS2 = 2In; k1 = 30%; k2 = 100%Vk>180In (RCT + 2RL)
for IS2 = 2In; k1 = 30%; k2 = 150%Vk>85In (RCT + 2RL)
Where Vk = kneepoint voltageof currenttransformer forthrough faultstability.
RCT = resistance ofcurrent transformersecondary circuit(ohms).
RL = lead resistance ofsingle lead fromrelay to currenttransformer (ohms).
Note: IF x X/R >120 generallyoccurs when the feeder beingprotected is short and is connecteddirectly to a power station busbar,where the generator X/R value ishigh.
High voltage withstand
Dielectric withstandIEC 60255-5:1977 2kV rms for 1 minute between all
case terminals connected togetherand the case earth terminal.
2kV rms for 1 minute between allterminals of independent circuits,with terminals on each circuitconnected together.
1kV rms for 1 minute acrossnormally open outgoing contactpairs.
High voltage impulseIEC 60255-5:1977 Three positive and three negative
impulses of 5kV peak, 1.2/50µs,0.5J between all terminalsconnected together and the caseearth terminal.
Three positive and three negativeimpulses of 5kV peak, 1.2/50µs,0.5J between all independentcircuits.
Three positive and three negativeimpulses of 5kV peak, 1.2/50µs,0.5J between all terminals, exceptcontact circuits.
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Electrical environment
High frequency disturbanceIEC 60255-22-1:1988 Class III 2.5kV peak between independent
circuits. 2.5kV peak betweenindependent circuits and case earth.
1kV peak across input circuits.
Fast transient disturbanceIEC 60255-22-4:1992 Class IVIEC 60801-4:1988 Level 4 4kV, 2.5kHz applied directly to
auxiliary supply.
4kV, 2.5kHz applied directly to allinputs.
Electrostatic dischargeIEC 60255-22-2:1989 Class IV 15kV – discharge in air with cover
in place.IEC 60801-2:1991 Level 4 8kV – point discharge with cover
removed.
EMC compliance89/336/EEC Compliance with the European
Commission directive on EMC isclaimed via the TechnicalConstruction File route.
EN 50081-2:1994EN 50082-2:1995 Generic standards were used to
establish conformity.
Product safety73/23/EEC Compliance with the European
Commission Low Voltage Directive.
EN 61010-1: 1993/A2: 1995 Compliance is demonstrated byEN 60950-1: 1992/A11: 1997 reference to generic safety
standards.
5
4
3
2
1
0 1 2 3 4 5
(a) 50Hz Ibias (x In)
Idiff(x In)
5
4
3
2
1
0 1 2 3 4 5
(b) 60Hz Ibias (x In)
Idiff(x In)
Relay settings:
IS1k1IS2k2
= 0.2 In= 30%= 2.0 In= 150%
25m
s
27ms
30ms
35ms
23ms
25ms
30ms
35ms
Figure 9: Typical operating times
14
Atmospheric environment
TemperatureIEC 60255-6:1988 Storage and transit
–25°C to +70°COperating –25°C to +55°C
IEC 60068-2-1:1990 ColdIEC 60068-2-2:1974 Dry heat
HumidityIEC 60068-2-3: 1969 56 days at 93% RH and 40°C
Enclosure protectionIEC 60529: 1989 IP50 (dust protected)
Mechanical environment
VibrationIEC 60255-21-1:1988 Response Class 1
CaseType LFCB relays are housed inMulti-module MIDOS cases.(See Figure 10).
Information Required with Order
Type of relay LFCB102, LFCB103 or LFCB202
Rated current 1A or 5A
Rated frequency 50Hz or 60Hz
Auxiliary supply voltages Vx(1) & Vx(2)
Type of communicationinterface being used:
Direct optical link Length of link and type of fibreused, including optical loss budget ifavailable.
Multiplexed link Channel data rate and interfacespecification.
Distance between relay andmultiplexing equipment.
A type MITZ unit is required foroptical to electrical signalconversions.
Case mounting Rack
Panel.
15
432
438
Removablecover
Hinged frontpanel
465483
178 101.6
Front
252
10
Push buttonprojection 10mm max.
10
450 min.
465.1 ±1.6
7 max.
31.75±0.4
12.7±0.4
Tolerance betweenany two holeswithin a distanceof 1mm ±0.4
10.67
Fixing hole detail
U ScaleU = 44.45
Allow a minimum of50mm for teeminal blockand wiringSide
Rack mounting
Panel mounting
483mm Rack detailsDimensions to IEC 297
432
438
Removablecover
Hinged frontpanel
443
201
Front
252
10
Push buttonprojection
10mm max.
10
440
Allow a minimum of 50mm forteeminal block and wiringSide
Panel cut-out detail
37
178
400
200
191180.5
Fixing holesØ5.4
All dimensions in mm
Mounting screws are not provided
Terminal screws:M4 x 8 brass Cheese Head withLockwashers are provided
37
Figure 10: Case outlines
St Leonards Works, Stafford, ST17 4LX EnglandTel: 44 (0) 1785 223251 Fax: 44 (0) 1785 212232 Email: [email protected] Internet: www.alstom.com
©1999 ALSTOM T&D Protection & Control Ltd
Our policy is one of continuous development. Accordingly the design of our products may change at any time. Whilst every effort is made to produce up to date literature, this brochure shouldonly be regarded as a guide and is intended for information purposes only. Its contents do not constitute an offer for sale or advice on the application of any product referred to in it.
ALSTOM T&D Protection & Control Ltd cannot be held responsible for any reliance on any decisions taken on its contents without specific advice.
Publication R4054M 029920 CPS Printed in England.
ALSTOM T&D Protection & Control Ltd