Static Phase Converter Question

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CJ5Dave

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Is there a downside to using an oversized (HP) static phase converter? I have a 1 to 1 1/2 HP converter on my 1 hp mill. Works fine. The guy I bought it from has some larger (5HP) converters. Was wanting another to temporarily test 3 phase machines. Is there a problem with using a 5 hp static converter on a 1 HP load?
 
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I tried to use a 3-5 hp static converter on a 1 hp motor a while back... it didn't work out well. The start capacitor never cut out...

I am assuming this happened because the motor was quite a bit smaller than the converter was rated for.

-Bear
 
The problem is capacitance
A 5 hp static converter may have a 400-500 Uf capacitor
You could only require 50-150 Uf to start a 1 hp motor
I would suggest adding a momentary switch to the generated leg to prevent the potential relay inside the static converter from constantly cycling. This shortens the lifespan of the start capacitor as well as the potential relay.
 
I went back and looked at my notes...

It would start the motor fine, but the light that indicates the start circuit is in use stays on, then after 30 seconds or so, the motor cuts off... (start capacitor overheats maybe). It wouldn't start again until it sat for a few minutes.

After wiring it to my rotary converter system, the motor runs fine...

-Bear
 
Static phase converters need to be tuned for the motor to really run well.
If you want a tester, you might graft a small idler onto it...
I wonder if one of the single phase soft starters might build nicely into a static converter... hmmm.

Sent from my SM-S911U using Tapatalk
 
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