Answer / monty

LBB called as a line breaker back up protection and it is used for the saftey of our equipment whenever fault occurs on line than the breaker of uper stream will be open if lower stream breaker will not operated.

Answer / tpfasil200

Local breaker backup or breaker fail relay(LBB)..It is used when the trip command is given and the breaker fails to open due to some mechanical problem. The protection is time delayed and initiated by all trip conditions.On LBB operation, busbar protection is initiated, as all the breakers connected to that particular bus to which the circuit is connected have to be tripped.I t also trips the tie breaker and sends a direct trip command to the other end breaker.

what is the diffrence between voltage and current?

11 Answers  

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there are a transformer and a motor. both are connected to 3phase, 415 Volt, 50Hz power supply. Both are working with induction principles. Then, why, motor is rotating and transformer is not rotating.

8 Answers  

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what is meant by real power,active power,reactive power & apprent power ?please explain it?

3 Answers  

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why occ curve is not tracing back when we are bringing rheostat back in reverse direction?

0 Answers  

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how on load transformer is chnage the Tapping ?

2 Answers  

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Why we does earthing for transformer neutral point

5 Answers   amps, DLF,

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what are the reasons for overheating in electrical machines?

3 Answers  

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what size of copper busbar use for 11kv 630A

3 Answers   ABB,

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what is the difference between high impedance and low impedance circuit?

2 Answers  

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What is the meaning of BREAKING and MAKING CAPACITY in case of CIRCUIT BREAKERS.

2 Answers  

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What is battery Amphere-hour? How the battery back up time period is calculated?

2 Answers  

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why battery dc voltage become Half when we check with respect to ground for example 120volts + and - terminals and when we check + terminal with Earth thats 60volts why 60volts we can not ground the battery.

6 Answers   GE,

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