2Features

l Complete phase and ground faultprotection for all types of ehv anduhv transmission lines

l Suitable for 3 pole or single poletripping

l High speed directional comparisonprotection using a signallingchannel. Operating time of 1/2cycle plus the signalling delay

l Optional distance zone, for back-up in the event of signalling failure,provides either under-reachinginstantaneous protection or over-reaching time delayed protection

l Alternative protection detects faultsoccurring following manual or auto-reclose

l Optional directional earth faultprotection

l Built-in voltage transformersupervision

l Integral operator interface for easyaccess to relay settings andfault/alarm records

l Continuous self-monitoring anddiagnostic facilities

l Remote interrogation via RS232Cserial link if required.

Benefits

The need for improved power lineprotection has led to the developmentof a directional comparison protectionrelay based on new operatingprinciples. This new protection has anumber of advantages, including:

l fast operating timel correct operation during evolving,

inter-circuit and cross-country faultsl ability to detect high resistance

faultsl excellent performance in the

presence of distorted waveformsl ability to withstand heavy circuit

loading without the loadencroachment problems of distanceprotection

l synchronised input signal samplingallows high sensitivity directionalmeasurements, and provides aninherent immunity to power swings

l insensitivity to CVT transients, andto the distortion caused by CTsaturation.

Type LFDCDigital Directional ComparisonProtection Relay

Figure 1: LFDC relay with hinged front cover removed to show the modular construction

sApplication

The directional comparison protectionrelay, type LFDC, is designed toprovide complete phase and groundfault protection for all types of of ehvand uhv transmission lines. Since theLFDC is based on an operatingprinciple significantly different from

Fir

vr(i) Faulted

(ii) Unfaulted

(iii)Superimposed

Fir

vpr VPF

Fir

vrZs

t=0

+

=

Figure 2: Relationship between the superimpoconventional distanced protection, it isan ideal partner for Micromho,Quadramho or Optimho distancerelays when two independentprotection systems are required.The directional comparison protectionconsists of an LFDC relay at each lineend, communication between therelays being provided by a signallingchannel and signalling equipment.Conventional on/off signallingequipment can be used (eg. powerline carrier, microwave, fibre optics),since the channel is only required totransmit a single command. Theprotection operates as a blocking orpermissive overreach scheme with anoptional weak infeed featureavailable for the permissive overreachschemes, and provides three pole orsingle and three pole tripping.The range of applications includes:l lines with or without series

compensationl uncompensated line adjacent to

series compensated linesl shunt compensated linesl lines requiring high sensitivity for

ground faultsl parallel lines with high mutual

coupling l lines with mixed overhead and

underground conductorsvr

vpr

vr

t=0

+

=

Voltage:

ed and the faulted power systemOperating Principle -Directional ComparisonProtection

High speed directional elementswithin each relay determine the faultdirection and produce either aforward or reverse decision. Thesedecisions are combined using either ablocking or permissive overreachscheme to generate the required tripsignals.The directional elements use the fault-generated changes in the voltage andcurrent signals at the relay location,referred to as the superimposedsignals, to determine the direction of afault. During a fault the voltage signalchanges by vr and the current signalchanges by ir.Figure 2 illustrates that the faultedpower system can be considered toconsist of two parts: the unfaultedsystem and the superimposed system.The superimposed system defines thechanges caused by the fault.The directional elements process thesignals vr and ir obtained from thesuperimposed system (see Figure2(iii). For a fault in the forwarddirection the superimposed current(ir) is related to the superimposedvoltage (vr) by the source impedancebehind the relaying point (Zs = Zs s) i.e.:

t=0

+

=

ipr

ir

ir

Current:3

ir = vr s

ZsSimilarly, for a fault in the reversedirection:

ir =+ vr Is

ZIswhere ZIs= ZIs Is is theeffective source impedancecorresponding to the protected lineplus the source at the remote in-feed.The directional elements evaluate thedirection of the fault by comparing thepolarity of the phase delayedsuperimposed voltage (vr ) withthe polarity of the superimposedcurrent (ir). The superimposedvoltage is phase delayed by 78;which approximates to the powersystem source angle for most systemconfigurations.A definite relationship exists betweenthe superimposed voltage and current:l for a forward fault vr and

ir are of opposite polarity and

aseector

Power swingblocking(optional)

Selfmonitoring &VT supervision

cDirectional Distance(optional)Fau

detec

Serial linkto

remote terminal

OperatorInterface

Va,

l for a reverse fault vr and irare of the same polarity.

The comparison is performed bymixing vr and ir in

Figure 3: Functional block diagram4

accordance with the equation.Dop=vr irvr+irFor a forward fault, since themagnitude of vr ir is greaterthan the magnitude of vr +ir,the directional operating signal, Dop,is positive.Conversely for a reverse fault, sincethe magnitude of vr +ir isgreater than the magnitude ofvr ir, Dop is negative.The directional elements evaluate thepolarity of Dop and compare its valueagainst operating thresholds todetermine fault direction. All faultscausing a current change of greaterthan 0.2n and a voltage change ofgreater than the voltage setting, aredetected. The directional elements willchange their directional decision ifrequired, for example during cross-country faults. For security, andchange in decision is supervised by adistance fault detector.lttor

Directionalearth fault(optional)

V & level

detectors

Phsel

Scheme logic

Alarms Send

Signallin

Trip

Vb, Vc a, b,

Operating Principle - Distance& Fault Detectors

The LFDC incorporates one complete

zone of distance protection and aseparate distance fault detector asshown in Figure 3.The optional menu-selectable distanceprotection does not rely on thesignalling channel for its operation,but is supervised by the forwarddirectional decision. It is intended togive back-up protection in the event ofsignalling failure, by acting as eitheran under-reaching instantaneousprotection, or a time delayed over-reaching protection providing back-upto the entire protected section. Thedistance zone is implemented usingsix forward-looking, memory polarisedmho distance elements (A-N, B-N, C-N, A-B, B-C, C-A).The fault detector, (comprising sixforward-looking and six reverse-looking, memory polarised mhodistance elements A-N, B-N, C-N, A-B,B-C, C-A) supervises the superimposeddirectional elements during inter-circuitor cross-country faults. The forwardfault detector also provides protectionfollowing manual or auto-reclosure,Statusinputs

Receive

g channel

when it is polarised by sound phasevoltages since no memory voltage isavailable.Each distance element is implemented

using a digital version of aconventional memory polarised mhoamplitude comparator. Thecomparator detects the fault as beingwithin its operating zone when:

Z + Vpol > V Z +Vpol where Vpol is the polarising voltageand Z is half the reach setting.

Protection Following BreakerClosure

The switch-on-to-fault feature offersinstantaneous protection followingmanual closure on to a fault. Trippingis normally initiated by the faultdetectors, except during 3 phaseclose-up faults, when the detection ofan over-current, under-voltagecondition instigates tripping. An optionalchannel-dependent directional earthfault protection detects closure on tohigh resistance faults. A similartechnique is used following auto-reclosure on to a fault, but in this caseswitch-on-to-fault is not indicated.

Optional Directional Earth FaultProtection

Most high resistance ground faults willbe detected by the superimposeddirection elements, but in someapplications additional directionalearth fault (DEF) protection isrequired. This is provided by a zerosequence DEF element which isusually polarised from the soundphase voltages and derives its signalsfrom the existing phase voltage andcurrent inputs. This element mayoperate as a channel-aidedprotection, sharing the same schemeand signalling channel as thedirectional comparison protection.Optional single pole tripping isavailable. A time delayed DEFprotection, independent of thesignalling channel, is also providedand can be used as an alternative orin addition to the channel-aided type.Both forms of DEF protection aremenu-selectable.

Optional Power SwingBlocking

Power swing and pole slip conditionspresent the relay with continuouslychanging currents and voltages,which generate superimposed signals.The superimposed signals producedby a power swing are generally toosmall to cause operation of thedirectional elements. However, anoptional, menu-selectable powerswing blocking feature is provided toprevent operation during pole slip, ornear pole slip conditions. Blockingoccurs if, while the system isbalanced, a directional elementattempts to operate forward followinga gradual increase in thesuperimposed current signal.

A

TRIP

ALARM

Light emitting diodes

OUT OF SERVICE Hardware

The LFDC relay is housed in a 4U(178mm) high case suitable for eitherrack or panel mounting. The relaycomprises 6 plug-in modules plus anoperator interface (GM0025). Themodules are classified as:l power supply (GM0026)l 8 element relay output module

(GM0032)l 14 element relay output module

(GM0032)l status input module (GM0022)l microcomputer module (GM0024)l analogue input/digital signal

processor (DSP) module (GM0023)

Figure 4: Operator interface on front panel

DIRECTIONALCOMPARISON

SET

RESET ACCEPT/RE

2 x 16 characterliquid crystal display

7 Keys only RESET and ACCEPT/READaccessible with front cover in placeEach of these modules is individuallytested and calibrated in the factory,consequently any module can beexchanged without the need torecalibrate the relay.The analogue input/digital signalprocessor module transforms the inputvoltage and current signals into aform suitable for digital processing,samples the signals, converts eachsample into an equivalent digitalnumber and processes the digitisedsamples in accordance with theprotection algorithm. The resultingoutput decision is then transferred tothe microcomputer module.The microcomputer module reads theoutput decision, processing this anddata from the status input module inaccordance with the protectionscheme logic. If necessary, themicrocomputer then activates theappropriate elements in the relayoutput modules.Two relay output modules, provide 34trip and alarm contacts. Twelve ofthese, arranged as four sets of trip A,trip B, trip C contacts, are used forbreaker tripping, breaker failinitiation, alarm annunciation andauto-reclose control. The status input module contains 8optically isolated inputs each of whichmonitors the status of an externalcontact.The operator interface described in

D

RELAY HEALTHY

PARALLEL

SERIAL

Test sockets5

the next section provides a simplemethod of interfacing with the relay.The power supply module converts theauxiliary dc voltage into the regulateddc voltage rails required by the LFDCrelay. High efficiency and isolationfrom the auxiliary supply are achievedby the use of a switching dc/dcconverter. A power fail monitoringcircuit with an alarm output contact isincluded.

Figure 5: External connection diagram: directional comparison relay type LFDC 101. Single breaker version

6

relay settings. If an error is detected,

l implement a comprehensive rangeof test options, for example, asimple on-load directional test.

Settings

The setting option allows the relay tobe set to suit each application.The user can select:l voltage sensitivity of the directional

elementsl reach (set directly in secondary

impedance) and residualcompensation of the distanceOperator Interface

All relay settings and records areaccessible from the integral operatorinterface shown in Figure 4.Information about the relay is displayedon the liquid crystal display (lcd); the7 keys drive the display and allow allthe available information to be viewed.The cursor keys (, , , ), the SETkey and the two test sockets are onlyaccessible after removing thetransparent front cover. These keys are used to select from amenu of operations which can bedisplayed on the lcd. One such optionallows the relay settings to be altered.Any change which will affect relayoperation does not become effectiveuntil the user has confirmed thechange by pressing the SET key.Accidental changes are prevented byallowing SET to be operative only atcertain points in the menu afterappropriate warnings have beendisplayed. Valid changes aretransferred to permanent memory, sothat if the supply is lost, correct relaysettings etc. are always reinstatedwhen the supply is restored.The test sockets can be used to sendinformation about the relay to either aparallel or serial printer. In addition,test points within the relay can bemonitored on the PARALLEL socket.When the relay trips, the date andtime of the fault, the element whichinitiated the trip and the faulty phases,are indicated on the lcd. If anothertrip occurs, the display isautomatically updated to show detailsof the new fault. The latest alarmconditions are also indicated. If faultor alarm indications are present whenthe supply is lost, they are reinstatedwhen the supply is restored.Each fault/alarm indication occupiesa single page (ie. 2 lines x 16characters) of the lcd. When severaldifferent indications occur each onecan be displayed by pressing theREAD key. When all indications havebeen read, they can be cleared bypressing the RESET key. For security,when the front cover is in place theuser has restricted access and cannotchange any parameters which affectrelay performance. However, theindications can still be read and reseta warning is displayed on the lcd.

Menu Options

The menu provides an extensive rangeof options, which allow the user to:l view and change the relay settingsl change the configuration (baud

rate, etc.) of the RS232C serial portl view time-tagged records of the lcd

indications for the last 10 alarmsl view time-tagged records of the lcd

indications for the last 3 faults.(Separate storage of alarms andfaults ensures that the last 3 faultsare always available even in theevent of multiple alarms)

l remove all past fault and alarmrecords from the memory

l view and change a calendar clockl transmit information to a printer, to

provide a print-out of relay settings,fault and alarm records. The userselects whether to transmit theinformation to the PARALLEL orSERIAL port

l view and change a relayidentification name for use on print-outssince the READ and RESET keysremain accessible. An additionalfeature is provided to allow the user toview (but not change) each relaysetting by repeated presses of theREAD key.The colour coded light emitting diodes(leds) show if any unusual conditionshave arisen. The red TRIP led isilluminated when the relay initiatesbreak tripping and is not extinguisheduntil the fault indication is reset. Theyellow ALARM led flashes when afault or alarm indication occurs andstays flashing until all indications havebeen read. It then remains lit (but notflashing) and only goes out when allindications are reset. The yellow OUTOF SERVICE led is illuminated whenthe relay is inhibited from operatingas a protection. The green RELAYHEALTHY led is always on when therelay is functioning correctly, but isswitched off if the relay becomesfaulty.The relay incorporates self testingincluding a continuous check of thepermanent memory which holds theprotection and fault detectorsl scheme type, for example: blocking,

permissive over reach, orpermissive over reach with weakinfeed echo and tripping

l whether the distance protection isenabled and if so, whether it isinstantaneous or time delayed

l whether the directional earth faultelement is enabled and if so,whether it is channel-aided or timedelayed or both

l value of scheme timersl single or three pole trippingl the conditions for which auto-

reclosure is blockedl whether the directional earth fault

element is enabled during switch-on-to-fault conditions

l whether power swing blocking isenabled

The menu is adaptive and onlydisplays the relevant settings; forexample, if the distance protectionhas been disabled its reach setting isnot required and is automaticallyremoved from the menu.7

8Remote Communications

All the options available on the menuare also available from a local orremote terminal via an RS232C serialcommunication port. Sockets areprovided on both the front and therear of the relay for temporary orpermanent connection respectively.The socket on the rear can alsointerface with a modem forcommunication over a suitable link,for instance a telephone line.

Self-Monitoring and VoltageTransformer Fuse/MCBSupervision

The LFDC has comprehensivecontinuous self-monitoring. If a failureoccurs, an alarm, is issued by closingthe relay inoperative alarm contactand extinguishing the RELAYHEALTHY led. Diagnostic informationis automatically displayed if the failureis such that it does not disable themain processor and lcd. In the eventof failure of a VT fuse, the VTsupervision logic disables the affecteddirectional elements, thereby blockingrelay operation. An optically coupledisolator monitors the auxiliary contactof a miniature circuit breaker (mcb) ifthe VT supplies are protected by anmcb instead of fuses. Energising theoptical isolator blocks relay operation.When a VT supply is lost, an alarm isissued by closing the VT supervisionalarm contact.

Contact Arrangements

The output contact arrangement forsingle breaker applications is shownin Figure 5. A version providing 6 setsof trip A, trip B and trip C contacts isalso available for double breakerapplications.22

20

18

16

140 25 50 75 100

Fault Position ( % of line from end A )

SIGNALLING DELAY 5ms

Trip time for relay at end A

Trip time for relay at end B

Ope

ratin

g Tim

e (ms

)

22

20

18

SIGNALLING DELAY 5ms

Trip time for relay at end A

g Tim

e (ms

)

Figure 6: Directional comparison protection typical 50Hz operating times for a permissive overreach schemeFigure 7: Directional comparison protection typical 60Hz operating times for apermissive overreach scheme

16

140 25 50 75 100

Fault Position ( % of line from end A )

Trip time for relay at end B

Ope

ratin

Technical Data

RatingsAC voltage (Vn) 100 to 120V rms phase-phaseAC current (n) 1A or 5A rms per phaseFrequency (fn) Nominal: 50 Hz or 60 Hz

Operative range: 47.0 to 51.0 Hz or57.0 to 62.0 Hz

Auxiliary dc voltage Nominal (V) Operative range (V)(Vx(1)) 24/27 19 32

30/34 24 41(Power supply) 48/54 37.5 65

110/125 87.5 150220/250 175 300

Auxiliary dc voltage Nominal (V) Operative range (V)(Vx(2)) 24/27 19 32

30/34 24 41(Status inputs) 48/54 37.5 65

110/125 87.5 150220/250 175 300Note: Vx(2) may be different fromVx(1)

Dynamic Range/Maximum overoad ratingsDynamic Range RatingsAC voltage 1.7Vn for measuring accuracy

AC current 35n for Directional measuringaccuracy25n for Distance measuringaccuracyMaximum Overlead RatigsAC voltage 2.2Vn continuous withstand

2.5Vn withstand for 10sAC current 4n continuous withstand

100n withstand for 1s (n=1A)80n withstand for 1s (n=5A)

BurdensAC voltage circuits

10

Operating timePermissive overreach scheme Closure of the signal send contact

(forward fault):50Hz minimum 6ms

typical 9ms60Hz minimum 5mstypical 8msClosure of the trip contact:

50Hz minimum 10ms + signalling delaytypical 13ms + signalling delay

60Hz minimum 9ms + signalling delaytypical 12ms + signalling delay

Blocking scheme Closure of the signal send contact(reverse fault);

50Hz minimum 7mstypical 9ms

60Hz minimum 6mstypical 8msClosure of the trip contact:

50Hz minimum 5ms + TPtypical 8ms + TP

60Hz minimum 4ms + TPtypical 7ms + TP(TP = maximum signalling delay + 6ms)

Reset time The trip contacts are sealed in untilthe relay detects a pole dead(minimum 64ms)

Fault detector

Features Forward and reverse distance faultdetectors which control the directionalelements during cross-country faultsand provide instantaneousprotection following breaker closure

Reach of the forward fault detector (FD) 0.200 to 250 (n = 1A)(positive sequence) 0.040 to 50.0 (n = 5A)

Note: settings are to 3 significant digits with a minimum step size of0.001

Reach of the reverse fault 120% of forward fault detector reachResidual compensation factor (KN) 0 to 400% in 5% steps

where: KN = 1. (Z L0 1). 100%3 Z L1

and ZL0 and ZL1 are the phasorvalues of zero and positive sequenceimpedances of the protected line.

Characteristic angle ph = N = 78% (fixed).

Current sensitivity The minimum operating current

( min) is:0.134n if z 3.2.

Inor0.134In x 3.2 if z < 3.2.

In x z InIf the distance protection is enabled,z is the distance reach setting (Z). Ifthe distance protection is disabled,z is the forward fault detector reachsetting (FD).

Voltage sensitivity The minimum operating voltage iszero.

Accuracy At fn and 20C:Reach: 10% up to SIR =60.

Operating time Switch-on-to-fault: closure of tripcontact:

50Hz minimum 26mstypical 41ms

60Hz minimum 26mstypical 38msFault evolving from an external to aninternal location: operating time ofthe fault detector following theinternal fault:

50Hz minimum 17mstypical 38ms

60Hz minimum 12mstypical 31ms

Channel independent distance protection (optional)Features One zone of distance protection

intended as a back-up in the event ofsignalling failure. Provides eitherunder-reaching instantaneousprotection or over-reaching timedelayed protection.

Reach of the distance zone (Z) 0.2 to 250 (In =1A)(positive sequence) 0.04 to 50 (In = 5A)

Note: settings are to 3 significantdigits with a minimum step size of0.001.

Residual compensation factor (KN) 0 to 400% in 5% steps where: KN = 1. ( ZL0 1).100%

3 ZL1and ZL0 and ZL1 are the phasorvalues of zero and positive sequenceimpedances of the protected line.

Characteristic angle ph = N = 78 (fixed).Current sensitivity The minimum operating current is

min. See section: fault detectorVoltage sensitivity The minimum operating voltage is zero.11

12Accuracy At fn and 20C:Reach: 5% up to SIR = 15Reach: 10% up to SIR = 60System Impedance Ratio (SIR) isdefined as:Zs/Z for phase-phase faultsZs/(Z + KN.Z) for ground faultswhere Zs is the total sourceimpedance per phase, Z is thedistance setting and KN in the neutralcompensation factor.

Timer ranges Time delayed distanceTZ(T) = 0.02s to 5.0s in 0.02s steps.

Timer accuracy TZ(T): 5msOperating time Under-reaching instantaneous

protection:Closure of the trip contact:

50Hz minimum 24mstypical 45ms

60Hz minimum 17mstypical 40ms

Directional earth fault (DEF) (optional)

Features Zero sequence directional elementprovides forward or reverse decisionsfor high resistance phase-groundfaults.

Residual current sensitivity The operating current is proportional(A + B + C) to the largest phase-phase current with

minimum values of:0.11In for forward decisions0.073In for reverse decisions

Residual voltage sensitivity The minimum operating voltage is(VA + VB + VC) zero for single phase-ground

faults, but equal to the directionalvoltage setting, Vs, for faultsoccurring following breaker closure.

Characteristic angle DEF = 78 (fixed).Channel-aided tripping Scheme co-ordination timers: TP, TD.(Option) See section on directional

comparison protection.Scheme initiation delay time:TDEF = 10ms to 200ms in 10ms steps(Accuracy = 5ms).

Time delayed trip Definite time range:(option) TDEF(T) = 0.5s to 10.0s in 0.1s steps.

(Accuracy = 10%).Operating time - Channel-aided DEF trip (TDEF = 10ms)Permissive overreach scheme: Closure of the trip contact:50Hz minimum 51ms + signalling delay

typical 56ms + signalling delay60Hz minimum 49ms + signalling delay

typical 52ms + signalling delay

Blocking scheme Closure of the trip contact:50Hz minimum 45ms + TPtypical 50ms + TP60Hz minimum 43ms + TP

typical 48ms + TP(TP = maximum signalling delay + 6ms)

Protection following breaker closure

Application Instantaneous tripping of the circuitbreaker for faults occurring followingline energisation. Manual closure ofthe breaker (SOTF protection) isassumed when all three poles havebeen open for 110s. All otherconditions of breaker closure areassumed to be auto-reclose.

Fault detector All faults except close-up 3 phase faultsand high resistance faults are detectedusing the fault detector (FD). Duringline energisation the fault detector issound phase polarised.

Level detectors Close-up 3 phase faults are detectedusing overcurrent and undervoltagelevel detectors (> < V).

Directional earth fault (option) High resistance faults are detected bythe channel-aided directional earthfaults protection (DEF).

Auxiliary Functions

Trip type1 or 3 pole Single pole tripping for

single phase faults and three poletripping for multiphase faults, or

3pole only Three pole tripping for all faults.Block auto-reclose A normally open or normally closed

contact is supplied to block or enableauto-reclose relays.The menu allows auto-reclose to beblocked or enabled for:l 3 phase faultsl 2 and 3 phase faultsl channel-aided DEF tripl channel out of service

Power swing blocking Enabled or disabled.

Output contacts

RatingsMake and carry 7500VA for 0.2s,

(maxima 30A, 300V ac or dc).Carry continuously 5A ac or dc.Break ac 1250VA

dc 50W resistive25W inductive at L/R = 40ms

(maxima 5A, 300V ac or dc).13

14Environmental withstand

Termperature Operative range 25C to +55CStorage and transport 25C to +70C

Humidity IEC 6823Long term damp heat 56 days at 93% RH and +40C.Enclosure protectionIEC 529 IP50 Category 2 (dust protected)VibrationIEC 255211 class 1 0.035mm displacement 1059Hz

0.5g acceleration 59150HzVoltage withstand

InsulationIEC 2555ANSI C37.901978 2kV rms for 1 minute between circuits

and case earth.2kV rms for 1 minute betweenindependent circuits.1.5kV rms for 1 minute across normallyopen contacts.

High voltage impulseIEC 2555 5kV peak, 1.2/50s, 0.5J

between circuits and case earth,between independent circuits andacross terminals of the same circuit

High frequency disturbanceIEC 255221 class IIIANSI C37.90.1 - 1989 2.5kV peak between circuits and case

earth.2.5kV peak between each independentcircuit and all other independent circuits1.0kV peak cross terminals of the samecircuit at 1MHz

Electrical fast transientsIEC draft document 41B, 1990ANSI C37.90.11989 4kV 5/50ns repetitive pulsesElectrostatic dischargeIEC 255222 class III 8kV discharge.Radiated electromagneticinterference test IEC 25522 3 class III 27-500MHz,10V/mDraft ANSI C37.90.2 25MHz - 1GHz 10V/m

Auxiliary dc supply

Supply interruptionsIEC 25511 Duration of interrupt 10ms.Supply rippleIEC 25511 ac component in dc, 12% of rated dc

value.Mechanical construction

Mechanical durabilityLoaded contact 10,000 operations minimumUnloaded contact 100,000 operations minimumCase dimensions Type LFDC relays are housed in

multi-module MIDOS cases (see Figure 8).Case weight 15kg.

Allow 50mm forterminal block andwiring

201

443

Hinged FrontPanel (GM0025) Front View (Cover removed)

37 252 10

10

178

Side view

25 way "D" connector(socket fitted) M4 earthing connection

BoardRef123456

Description

Power supplyRelay outputRelay outputStatus inputMicro computerAnalogue input/DSP

Board No.

GM0026GM0032GM0032GM0022GM0024GM0023

1 2 3 4 5 615

Figure 8a: Arrangement and outline: panel mounting

Rear view

Front view(with cover and hinged front

panel removed)

440

200

180.

519

1

Panel cut-out detail

Fixing holes5.4

400

Terminal block is numbered 1 to 28unless otherwise stated

2

27 28

28 way maxeach way accepting:-2M4 Ring terminalsor24,8 x 0,8Snap on terminalsor1 Ring+1 Snap on terminal

25 way "D"connector detail

14

13 25

1

1

T.B.A

T.B.E

T.B.F

T.B.G

T.B.H

SK1

Figure 8b: Arrangement and outline: rack mounting

178(4U)

465.1

Hinged FrontPanel (GM0025) Front View (Cover removed)

101.6

37.7

483

Allow 50mm forterminal block andwiring

37 252 10

10 Side view

Front view(with cover and hinged front

panel removed)

Fixing slot10,6 long * 7 wide 25 way "D" connector

(socket fitted) M4 earthing connection

Rear view

T.B.A

T.B.E

T.B.F

T.B.G

T.B.H

SK1

Terminal blockdetail

2

27 28

28 way maxeach way accepting:-2M4 Ring terminalsor24,8 x 0,8Snap on terminalsor1 Ring+1 Snap on terminal

1

14

13 25

1

25 way "D"connector detail

BoardRef123456

Description

Power supplyRelay outputRelay outputStatus inputMicro computerAnalogue input/DSP

Board No.

GM0026GM0032GM0032GM0022GM0024GM0023

1 2 3 4 5 6

Information Required with Order

Nominal current rating n: 1A or 5AAuxiliary dc voltage Vx(1) 24/27V, 30/34V, 48/54V, 110/125V, 220/250VAuxiliary dc voltage Vx(2) 24/27V, 30/34V, 48/54V, 110/125V, 220/250VMounting arrangements rack or panel, horizontalNominal frequency 50Hz or 60HzSingle or double breaker Type LFDC101 (4 sets of trip contacts for single breaker applications) or

type LFDC102 (6 sets of trip contacts for double breaker applications).

FeaturesBenefitsApplicationOperating Principle -Directional Comparison ProtectionOperating Principle - Distance & Fault DetectorsProtection Following Breaker ClosureOptional Directional Earth Fault ProtectionOptional Power Swing BlockingHardwareOperator InterfaceMenu OptionsSettingsRemote CommunicationsSelf-Monitoring and Voltage Transformer Fuse/MCB SupervisionContact ArrangementsTechnical DataRatingsDynamic Range/Maximum overoad ratingsBurdensDirectional comparison protectionFault detectorChannel independent distance protection (optional)Directional earth fault (DEF) (optional)Protection following breaker closureProtection following breaker closureAuxiliary FunctionsOutput contactsEnvironmental withstandVoltage withstandAuxiliary dc supplyMechanical construction

Information Required with Order