DIYer asks about his AVR in the ST style generator

Question for George:  Hi I live in North Queensland Australia, I found your site while trying to fix a problem with my generator.  The AVR died and I have been sent a new one that is not the same as the original so wiring mods are needed, problem is that the wiring diagram supplied with the unit is not compatible with the unit as the diagram has not got the AVR on it.  The generator is a Mindong st10, I wonder if you could help me out with  a wiring dia for the new AVR, it is an  EA15A. This is becoming a problem for me as we do not have grid power and rely solely on generator power much appreciated.

Gary A.

George’s Reply: Hi Gary, good news? I think your supplier has sent you a better AVR than what your unit was assembled with. How good it is, I don’t know, and hopefully, we’ll get some comment on this page.

My philosophy has caused me to avoid simple AVRs in the past because of the failure rates, few of these regulators have features built in that will allow the installer to limit field current, and some Simple AVRS will overdrive the field to the point where they destroy themselves or even the field. We need learn how good this EA15A is, and what we might add to it.

The ST is not the only generator supplied with simple AVRs, there are quite a few small generators that run out of fuel with a load on, and the AVR literally destroys itself or another component in the process. The operator refuels the gen set and finds the generator no longer works. I have also written about the destruction of a well pump coupling in a submersible pump caused by the generator running out of fuel. When I investigated that failure, I found a warning on the pump manufacture’s site that a generator running wild like they do ‘when’ they run out of fuel could destroy the pump coupling! This is a side note, and not a problem the AVR creates.

If your install is made best, (especially if you have a submersible well pump) you will consider a low voltage release as well. Many of us have run for years without the safeguards and we get away with it… “we’re gambling”, and the deeper that pump is down in the ground, the more we have at risk.

When running an AVR, You might eliminate some problems by placing a fuse or breaker in series with the field, this would keep a simple AVR from raising the current insanely high.

The new year is just a stones toss from here, 2011. Much of what I have written about the ST types to this point may be dated? I have seen that China has decided to have a different standard for exports, and this appears to give manufacturers the latitude to move away from the old standards that their government put in place to protect the Chinese people. Does this mean that China has joined India as per Quality Control, and the STs need be judged as individuals? some are very useful, some have problems I think.

It’s easy to google up “Voltage Regulator EA15A”, looks to be a universal regulator, and it looks far better than what I have seen in the past. How well they work might become a discussion on this page? How universal are they? I would really appreciate you sharing the outcome. Go back to your supplier for specific hook up information, I would be surprised if there is much more that a DC voltage supply in, and connection out to supply the field current to the brushes. Anyone out there have schemetics or more information on this unit?

Gary you send a sketch as to how the old AVR was wired in and why you think this one is different?

George B.