Portable generators, part II

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Old 03-17-13, 02:03 AM
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Portable generators, part II

I didn't want to hijack the portable generators thread.
http://www.doityourself.com/forum/el...enerators.html
But I have a couple of questions along the same lines.

I've heard of soft start kits for air conditioners. Are they available for other types of motors (well pumps, circulators, sump pumps)? Would they be any help with a generator's tendency to bog down when motors start up?

Are there any control circuits available that would throttle up the generator and delay the motor start until the output could handle it?
 
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Old 03-17-13, 06:28 AM
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I've installed a few soft starts on bridge cranes and conveyors, but that was 3 phase and a long time ago. Now I use frequency drives because I not only want the ability to ramp up and down my speed but I do change speeds.

I do like your idea! It would drop the starting load torque because you can ramp up the speed over a set amount of time. I've used them on 3 phase stuff, so I don't have the answer on how the soft start would effect a capacitor circuit on a well pump.

As for revving up the generator, you are raising the voltage and the frequency. How good is that for the generator and the motor?

One thing I found with well pumps that refuse to start was to drain off the water pressure in the storage tank. ( open faucets ) By doing that, I reduce the starting load on the pump, its not trying to pump against a 30psi head pressure. At my Parents house, I've isolated the well pump when using a generator. Either running the well, or everything else by switching the breakers on and off. It was a that point I would drain off the water pressure and it was just enough to get the pump going.
 
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Old 03-17-13, 06:33 AM
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So is your well pump kicking the breaker when it starts?
Can it power the pump with no other loads?

Maybe you can get a current sensor that keeps your pump off until the generator is seeing less load.
 
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Old 03-18-13, 02:29 AM
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Sorry DMCman, I didn't mean to misrepresent myself. I'm an electrician. It's a common problem. Go to the link in post #1 for explanation.

"So is your well pump kicking the breaker when it starts?"

No, bog down = RPMs drop on the genset which reduces output voltage. The genset's governor gives it the gas and it takes a while for the genset to rev back up again. Typically, under these conditions, the load motor(well pump) will not start.

"Can it power the pump with no other loads?"

Startup, no. Inrush current is too high(LRA). But it could easily keep the pump running. Running Load Amps (RLA) is within the gensets capacity.
 
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