Generator Failure

The moral being generators should have phase detection/protection. Many problems can be avoided following Author Larry Bush's generator advice and procedures http://www.feedforward.com.au/emergency_power_generator.htm

1. What did the trouble shooting already performed indicate?

2. What did the generator manufacturer's tech service say, when contacted?

3. What did the on-site visit by a service tech indicate?

4. What have you done, so far, to fix the problem?

The primary decision making criteria for selecting this oversized 3ph genset for this pump was most probably that it was the one they have on hand.

Maybe after fixing it they should consider some useful dummy loads on the other phases. Small airconditioners perhaps? Have to weigh up fuel costs V frequent repair cost.

It's hot here too. Worksite airconditioning has got to start being part of regular PPE in hot weather.

I agree, but it illustrates the point that the old "the plug fits the socket so it must work ok" mentality often conforms to the Law of Unintended Consequences.

I am less inclined to blame the small single phase load as I am to blame the general lack of load itself.

Very few smaller gensets are all that fussy about phase balancing but I am aware that long duration running at light loads can cause the rotor brushes to glaze over due to running at minimal current levels. I've seen this a number of times in portable welder generator units that spent a lot of time being used on work sites for auxiliary power sources where they would run for days never seeing a load bigger than a few cell phone chargers and cordless tool chargers.

This glazing can cause intermittent open circuit conditions in the rotor which will act like a hugh induction coil causing a high voltage spike to be produced which when high enough will break through the glaze and hit the voltage regulator with a pretty serious spike. Do that enough times and something will have to give which is usually the diodes or the switching devices in the regulator.

The other thought is that the rotor may have an intermittent short to the frame which causes a overloading of the voltage regulator. That too would cause the diodes to explode.

What brushes?

Why don't you check the single phase motor and make sure it or its capacitor isn't faulty.

Thank you very much indeed for some very useful responses.

If you have a 3 phase to single phase transformer of the proper voltage rating, use that.

Thank you for your advise.

Do you have a specification for such a transformer? This will really help me.

Yes. This is called a control transformer. Use a 415 volt 3 phase Primary / 240 volt singe phase secondary with a 10 amp rating. You can also purchase a transformer with a fuse clips mounted for primary and secondary protection.

Thank you for your time, it is highly appreciated.

I suppose the dedicated single phase generators use such a transformer.

Only if there is a need. A 3 phase generator has a different need than a single phase generator has.