One Parallel Generator 'Grabbing' Amps

How do you know it is not the meter? Have you checked with, say, a clamp-around ammeter?

Thanks for the message.

No. But I ran each generator alone, with practically the same load and each one showed the same Kw and the same amps. It's only when #2 is parallel that the amp difference shows up. Also I measured the output of the CT's that supply transducers for the PMS system and supply the meters. When single running they are all about the same within a very small margin, as soon as #2 is in parallel the transducer input and the meter input (hence the reading) jumps up proportionally to the 500A difference.

This looks like an interesting thread to follow. It looks like the generator in question has an internal load. Is there a way to see if the gen has load running alone?

Thanks Mike,

I like your thought process.

You mean run the generator 'off line' and try to measure if there is any 'internal' load.

These generators are on a ship, I don't have easy access, but I will try to think of a way. I think the CT's that supply the meter and PMS tranducers are upstream of the Air Circuit Breaker (ACB) so they only 'read' when the ACB is closed.

Jeff.

You only show the list of meters available as kW, V, Hz and A. Has anyone considered kVA and PF? Could be a reactive power flow between the 3 gens when all are sharing the load, such that two are producing VARs and the other absorbing (or the opposite). If the PMS only looks at the kW, it won't consider reactive flows. Has anyone looked at the excitation system of the suspect gen? Is there underexcitation protection?

As for the meter, that would be easy to check by connecting the meter to an external AC current source. Depending on the CT secondary current range (0-5A?) you increase in steps and record what the meter reads for each. That's basic test. The other question is whether the CTs have some non-linearity in the operating range (unlikely). Have you checked that the CTs are the same on all 3 machines? Do you see the same 500A difference on all 3 phases of this gen?