[stevehull]

It is my understanding that "softstarts" reduce the initial current peak (6-7 times nominal running current) from a few msec to a couple hundred msec. By spreading out the starting load/torque, the peak current is reduced, the undervoltage minimized and electric motor/compressor is less stressed both electrically and mechanically.

This could be a very good item to add to a deep well submersible water pump.

What I don't know is the amps x time characteristic of deep well pumps vs a standard above grade compressor/electric motor.

I do see a softstart on the geothermal units I have here and the start up voltage drop is much reduced as there is little start up "blink" observed on house lights (compared to a unit with no softstart).

My clamp on current meter only tells me peak current or steady state current - not the time issue. I suppose I could drag out my storage oscilloscope to the pump house and look at starting current with a limiting resistor to get the time duration of this start up current surge.

Again, the issue is supplying the well pump with generator power during grid power loss. Even though the start current is only a fraction of the run current, I have observed what happens when the generator is not large enough to supply start up pump current.

During a former power outage (spring storms), my neighbor burned out his deep well pump by having a generator that was big enough to supply running steady state current, but not the starting peak current. In addition to being out of power, he was then out of water.

He was using a small Honda (~1.5 kW) generator only to the well pump (1 HP). At pump start up, the pump house electric light bulb would noticeably dim for 8-10 seconds and the generator slowed considerably. Then, the generator would speed up, the light brightened and he had water. Then, about two days later, the pump died while on this generator. When we pulled it and did the tear down necropsy, the motor windings appeared burned. My belief was that this repeated starting high current and low voltage fried his pump (caused by the too small generator).

Of course, this could just be coincidence, but the pump was only three years old.

I clearly want to avoid that situation . . . That is why I have been using larger PTO generators and running through lots of fuel.

Bottom line - do you think that a softstart would be beneficial for the water pump when running on emergency power?. $235 is a lot for just a "look see". Maybe it would also extend water pump life . . .

Steve