"Ignoramus19393" wrote in message
...
On Fri, 19 Aug 2005 02:19:30 GMT, Jerry Martes
wrote:

"Ignoramus19393" wrote in message
.. .
I built another self starting phase converter kit, with a 7.5 HP
idler.

That's because I have a 5 HP 3 phase compressor that I want to sell,
and I want to offer a phase converter with it so that it appeals to
garage mechanic types.

Almost everything is great. The compressor runs beautifully with the
7.5 HP idler. Voltages between legs are 240, 250, and 256 volts, which
I consider well balanced.

Here's the problem. The idler motor vibrates without load. As soon as
I turn on the 5 HP load, vibration stops. I am not sure why that is.

If I remove incoming 240V by turning the contactor off, vibration
stops instantly as well as the rotors spins down.

Any thoughts as to why that could be happening?

i

I

I'd be curious to know if the vibration is there when the RUN capacitor
is
eliminated.
If you insist that balancing the RPC output voltages is important,
ignor
this capacitor removal suggestion.

Jerry, I have only one run capacitor between legs 1-3. That's what
allows the RPC to start. There is, possibly, too much capacitance. I
will experiment...

i

I

My point is -- There is very little to ever be gained from leaving the
start caoacitor IN the circuit, especially if the ultimate use of the RPC is
to power a compressor with an unloader.
Bump the capacitor into the circuit only long enough to get the idler
spinning a little then disconnect it. It doesnt add to the power
delivering capacity of the RPC.
Correct me if I'm wrong or if I misunderstand.

Jerry