70KVA Generator Keeps Tripping Out

[CathalX]

Imbalance is a possibility. However, I had the board professionally built.

All of the heating is evenly balanced across the three phases as are the lights.

The only point of possible imbalance is on the power. It is spread across two phases. I woud ask how balanced does it need to be?

When the mains to the house is connected, I will have a 100A fuse on each phase as opposed to a triple MCB across all three.

Logic would tell me that if the problem is not the generator, then the phase causing this problem would lose power by its fue blowing when the mains is connected.

 

[andy]

Imbalance is a possibility. However, I had the board professionally built.

All of the heating is evenly balanced across the three phases as are the lights.

The only point of possible imbalance is on the power. It is spread across two phases. I woud ask how balanced does it need to be?

When the mains to the house is connected, I will have a 100A fuse on each phase as opposed to a triple MCB across all three.

Logic would tell me that if the problem is not the generator, then the phase causing this problem would lose power by its fue blowing when the mains is connected.

get a clamp meter and measure what power is bein drawn on each phase

 

[pc1962]

Hi,

Pretty sure this is a generator problem, you should get the guy back to check on load. Surely a genny this size has appropriate instrumentation on it for monitoring current/ frequency/power. I still cant work out from your post if the actual 3 phase MCB on the generator is tripping or not. However, as its extremely unlickely to be a power surge. My gut reaction would be the "under frequency rolloff". This is a monitor on the alternators AVR which will stop vlotage generation below a certain frequency[speed of engine proportional to frequency] and consequently if you have a under voltage trip will trip the genny breaker even if it doesnt trip the breaker you will still lose generation capability. Obviously, this would not be seen at light loads. Cause-dirty engine fuel filters-fuel pump requires calibration-incorrectly set governor, either way you need to get the guy back out and test the genny under load and ask him the last time the genny was maintained. Then tell him you want part of your money back!!!!

Hope this helps
pc

 

[HDRW]

Imbalance is a possibility. However, I had the board professionally built.

All of the heating is evenly balanced across the three phases as are the lights.

But presumably the heating is thermostatic - I wonder if one of the heating circuits cuts out due to the thermostat reaching its set point, and the imbalance caused by the sudden lightening of load causes the trip?

Logic would tell me that if the problem is not the generator, then the phase causing this problem would lose power by its fue blowing when the mains is connected.

The problem may not be in one or t'other, but an interaction between them!

I don't think it is likely that a fuse will blow on mains supply - they're not blowing now. The genny is 70kVA / 3 = 23.3kVA per phase, / 230V = 101A - I think they're close enough that there's not going to be a real difference.

Cheers,

Howard

 

[CathalX]

Generator was replaced. Apparently the Triple MCB was fused at 20KVA and had been added as a customer requirement. I assumed that it was 70KVA as was written on the Generator Spec.

 

[plugwash]

in other words they forgot to undo what they had done for one customer when they provided the generator to another, sounds a pretty typical type of screwup.