Generator Protection Relay

[nialmul]

Hi,

I am currently working on an Areva Micom P342 generator protection relay.

I am have some difficulties and I was hopeful that someone here may be familiar with these relays or generator protection relays in general.

1) Must voltage or resistor always be connected to the Vneutral terminals C23, C24?

2) Should the any/all protection functions isolate the prime mover as well as the generator. Prime mover is a DC motor.

3) The generator is small 2kW. And produced a nominal current of 2-4 amps. Could it damage the relay connecting this current direct to the CT terminals without a CT?

4) Similar the nominal voltage is rated at 220V. I had planned using 3 standard 2:1 single phase transformers connected in delta. Would there be any problem with this?

 

[DTR2011]

Hi-

I am not 100% familiar with the relay, however....

#1 - If you do not connect anything to a terminal, no harm. This is for large machines that have their neutrals impedance grounded.

#2 Generally speaking, the prime mover is hard coupled to the generator and there is not a way to decouple. The choice of functions can protect the prime mover (reverse power, in advertant energization, etc), but the schemes typically isolate the generator/prime mover from the power system, not from each other.

#3 - Yes. You need CT's to provide a low voltage signal and for safety. YOu would likely not want to run you power cables trough the relay anyway.

#4 - What is the output configuration of the generator? If it is delta, you could likely use 2 VT's in an open delta configuration. At 220V, the VTs are probably inexpensive enough to warrant putting in a third in a Star Configuration for better metering, etc.

Hope this helps.

 

[tomatge]

You are using a Micom P342 for a 2kW generator? Astonishing. The relay must cost more than the machine it's protecting!

 

[FreddyNurk]

tomatge, I've got a suspicion that this is a test bench, but could also be way off the mark.

I've seen expensive generator controllers hooked up to small alternators (with small motors as prime movers) as a scale simulator of systems. It wouldn't surprise me if this was the case.