Instantaneous device setting protecting a generator
Instantaneous device setting protecting a generator
(OP)
Wich is the usual setting in % of FLA of an instantaneous relay (50), protecting a generator against external faults?
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Instantaneous device setting protecting a generator
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RE: Instantaneous device setting protecting a generator
Rafiq Bulsara
http://www.srengineersct.com
RE: Instantaneous device setting protecting a generator
I thought I could use the 50 to cut the deliver of current to the bus it's connected in case of a 3ph short circuit there.
RE: Instantaneous device setting protecting a generator
RE: Instantaneous device setting protecting a generator
The system is something like this:
network---xfmr---bus---generator
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other loads
If there is a 3ph short circuit in the bus, should I need to cordinate de generator device 50? Isn't the best thing to trip the generator as soon as possible, no matter what happens with upsteram relays?
That's why I asked for an used value, regardless of coordination.
thanks everybody!
RE: Instantaneous device setting protecting a generator
RE: Instantaneous device setting protecting a generator
Generators also behave much differently under close-in faults than a utility source. It may not deliver the current you may think it will. There are other techniques to address those.
So as davidbeach said, get an experienced professional to do the coordination study and settings. This is not something you want to learn via free advices with answers to hypothetical scenarios.
Rafiq Bulsara
http://www.srengineersct.com
RE: Instantaneous device setting protecting a generator
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If we learn from our mistakes I'm getting a great education!
RE: Instantaneous device setting protecting a generator
RE: Instantaneous device setting protecting a generator
This what I did after all:
I deactivate the instantaneous protection and set the Long time overcurrent protection 1.15 FLA (IEEE Buff book). Time delay was coordinated to trip the CB with the 51V (voltage restrain)as backup of the feeders protection.