User Manual

DIR 1000587R0002 (L3821)
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3.1.9.2.2 Start-up threshold “S”
Thestart-upfunctioncanbeselectedinthecasewherethecurvewithxedtimeisselected.
Thisfunctioncanbedisabled;itisasettingcharacteristicofthesingleprotectionunits.
Thestart-upfunctionenablestheprotectionthreshold(SandG)tobechangedduringa“ts”timeinterval,startingfrom“start-up”.Thelattermust
beintendedasfollows:
-RMSvalueofmaximumcurrentpassingoveronesingleadjustablethreshold(0.1...10In,by0.1Insteps).Anewstartispossibleafterthecurrent
hasdroppedbelowthisthreshold.
I
t h
StartUp
StartUp
Programmedtime
ts
ThresholdI
2
• Start-up time
Start-uptimeisdifferentforallprotectionsconcerned.
Range:0.1s...30s,withstepsof0.01s.
3.1.9.3 Protection “I”
Theprotectionisenabled/disabledfromthemenu.
Intheeventzoneselectivity“S”isactive,duringtrippingoftherelayfor“I”,theZSOoutputsignalisactivatedtoguaranteecorrectoperationof
therelayonsupplyside(andonloadside).
3.1.9.4 Protection for maintenance mode “MM”
Theprotectionisenabled/disabledfromthemenu.
Theprotectionisactivatedwhenisenabledandwhenbinaryinputishigh(24Vdcseepar.3.1.4.1).
3.1.9.5 Protection “G”
Thisprotectioncanbedisabled;itcanbeofthexedtime(t=k)orinversetime(t=k/i
2
)type.Inthelattercase,triptimeisgivenbytheexpression








,
2
I
2
max t
4
whereI=I
f
/I
4
, I
f
isthefaultcurrentandI
4
theprotectionthreshold.
NB:Timeexpressedinseconds.
It is possible to disable trip control of protection (“Enable Trip: Off”).
For the whole duration of the earth fault, circuit-breaker opening does not take place, but only the alarm condition is signaled
(“Alarm” LED lit and alarm message).
Theunitcanprovidetwodifferenttypesofearthfaultprotection,simultaneously:
Internal protection G
Thisisprovidedinsidetherelaybyvectoriallysummingphaseandneutralcurrents.Faultcurrentisdenedbythefollowingformula:
Ifthecircuitshowsnofaults,themoduleofthesumofthesecurrentsisalwaysnil;viceversa,thevalueofthefaultcurrenttakesonalargerand
largervaluedependingonsizeoffault.Thisoperatingmodeisenabledbydefault.
N.B.:itcanbeusedalsowithCSforanexternalneutral.