Anyone installed a Soft-Start kit for a compressor?

[Lloyd-ss]

I know that the starting current (inrush?) for a compressor (air, heat pump, AC, etc) can be several times greater than the run amps and even the locked rotor amps. I am trying to size a new portable backup generator but am having a hard time justifying one large enough to start any compressors or machinery motors. The soft-start kits I have seen advertised are supposed to control/moderate the starting current so that a portable generator can safely start the motor. Anyone know anything about these. Have you installed one? Is there a risk to the motor it is installed on? They seem to come in various price-ranges, too.
In particular, I need something for my geothermal heatpump. The compressor is about to go out of warranty so I am not concerned with voiding the mfg warranty.
Any and all help would be greatly appreciated. Thank you.
Lloyd
P.S. Just regular 250v single phase.

 

[GreenTwin]

I think a typical induction motor will draw six times normal current when starting.
Soft starting would no doubt reduce this, but you still need to develop enough torque to get the motor up to speed.
I have one plant that starts 5,000 hp motors across-the-line, and they have to telephone the power company to temporarily adjust the instantaneous trip of their breakers when these motors are starting.

When I specify a generator, I have the supplier run a starting program, with worst-case on the motor starting.
Generally, in industry, where possible, the load is shed via various options when starting a large motor.
Air compressors have a pressure relief valve to do the same.

I need to research 240 volt soft starters to give any kind of real answer.
Solid state electronics connected to a generator can require it to be derated, so you may or may not achieve anything using a soft starter.
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[GreenTwin]

A white paper summary with some good info.
There are a number of parameters to consider.

https://www.eaton.com/content/dam/e...-soft-starter-generator-power-ap03902013e.pdf

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[GreenTwin]

Another link.

https://norwall.com/products/generac-sure-start-16-32-fla-soft-start-kit-8008/

I personally would opt for a larger generator, with across the line starting, since sooner or later the electronics in a soft starter will fail.
Solid state devices are very prone to failure during overvoltages caused by lightning strikes, so if you do use a solid state starter, you may want to also use a good surge suppressor.

A "good" surge suppressor is not the one with the highest amp rating, but rather the one that has the best let-thru voltage clamping.
It is the let-thru voltage that spikes electronics and causes failures.
This is the product I use at home, and work municipal projects; it has the best track record in the industry, and is used extensively in Florida, with is the "lightning capital of the world". This product really works, and is small; about the size of a brick.

https://www.surgesuppression.com/

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