what is the function of LBB relay

Answer Posted / manikandan.c

LBB means local breaker backup protection.This relays are
associated with some important main relays like
distance,differential and busbar relays.If main relays are
fail to open circuit breaker(or any mechanical problem in
breaker) under fault conditions,The LBB relay gives trip
command the same breaker for 100ms.If also not open means
next 200ms,It gives initiation for main busbar protection
and followed by busbar protection operated and direct trip
command send to the remote end.And finally protect the power
system.

Is This Answer Correct ?    25 Yes 5 No



Post New Answer       View All Answers


Please Help Members By Posting Answers For Below Questions

how many safety really of DG sets.

1721


how to calculate the loss tangent of electrical cables

1604


How do i perform grounding of star point of Genset (400V) for making connection with step up transformer of DELTA-DELTA (400V to 20KV) ? while Genset itself has its own neutral and grounding bus bar inside genset breaker box whereas we have another neutral and grounding busbar in synchronizing panel next to genset at maximum distance of 6meter, would someone pls advice if we can only perform neutral grounding in synchronizing panel or should we ground neutral on both places inside genset breaker box and synchronizing panel.

1260


When we need up only in o/p 440v, so why we use directly in 11kva in input?

1274


Why AC current leads voltage in capacitor and how?

1614






What is meant by system?

651


What is diversity factor in electric installations?

703


What is contract demand in solar system?

1128


what is high - pot test. what's its use?????

1610


in the directional overcurrent and earthfault protection,normally we are setting the angle 45 deg lead for phase fault overcurrent and -45 deg lead for earthfault fro forward direction.but both the fault are operating on the same angle region only.why?how the relay will response?

1410


Which device of PlC does share load between DG sets when DG are running in perallel?

1553


Explain in brief description about the operation of DG sets.

1878


State the formula for overall efficiency of thermal power station

2540


how to test the turn ratio of 3 phase transformer using volt meter shoe the curcit diagram.

1845


How to know the Max. current caring capacity of the cable by its size ?

1175