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# What would cause a generator to trip on 32R?

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## What would cause a generator to trip on 32R?

Which of the following would cause a generator to trip on 32R?

Correct Answer: Voltage lower than utility
Your Answer: None of the above

Lower voltage causes a loss of field trip not a reverse power trip.
A 32R reverse power trip is caused by loss of prime mover power. (Turbine trip loss of steam to turbine etc. )

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I'm not a relay tech by any means but if a generator was putting out a lower voltage than what was on the line would power not flow back into the generator?

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If a generator is running in parallel with utility (sometimes referred to as peak shaving) and a 32R trip it is most likely due to the operator synching in at too low of a frequency which could cause the utility to start motoring the generator, or it could be that the P.F. is starting to go leading (taking on more capacitive reactance which will cause current to flow to the excitation field) which could be from voltage being too low.

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Originally Posted by djohnson18
Which of the following would cause a generator to trip on 32R?

Correct Answer: Voltage lower than utility
Your Answer: None of the above

Lower voltage causes a loss of field trip not a reverse power trip.
A 32R reverse power trip is caused by loss of prime mover power. (Turbine trip loss of steam to turbine etc. )
It's not real power but capacative reactance power that would flow back to the generator if the voltage is too low. Now as far as how the 32R element works. It compares your voltage phase angle to your current phase angle to tell what direction power is flowing (ELI the ICE man) so a 32 device is going to trip whether its a reverse power or reverse current. You never want your generators pwer factor to go leading (or at last not too far leading) because your relay does not know the difference between reverse power and reverse current because the phase angle relationship is so similar.

Last edited by shane.e.randall; February 11, 2016 at 08:13 AM.

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## 32R Reverse Power

Originally Posted by veracon0700
I'm not a relay tech by any means but if a generator was putting out a lower voltage than what was on the line would power not flow back into the generator?
The generator could have a lower voltage and produce more current to still provide a positive power. Reverse power is most evident when the prime mover is experiencing a loss of power.

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