View Full Version : static phase converter trouble

10-14-2013, 01:15 PM
First, before any of get up in grill about using a VFD instead, I already had this phase converter and figured I'd hook it up to see what happened.

I wired the setup according to the supplied schematic I have and when I turn it on it hums loudly. You could go so far as to call it a buzz. The literature that came with it says it should just click once. Is it possible that:

The lines from the panel box are hooked to the converter backward? I thought it wouldn't matter because it's AC.

I wired the reversing switch wrong, so the converter is trying to start up under load?

The converter's no good?

Or something else?

10-14-2013, 01:32 PM
Is the H.P. rating of the converter larger than the motor it is trying to run. . Such as converter rating 3-5 H.P. and the machine motor less tan the 5 H.P. Also what brand of converter. Two wires plus a ground go to the main panel . 3 wires go to the machine .If machine runs backward just switch any 2 of the 3 wires.
Maybe this is some help . The capacitor in the converter could be bad if it is a old converter.

10-14-2013, 01:58 PM
It sounds as the start capacitor is not in circuit or wrong value?
Start it off load, if not already.
Is it auto start or manual push button?
If auto, the click you hear is most likely the contactor engaging which also should initiate the short duration cap start circuit.

10-14-2013, 03:09 PM
It's a smith electric from Grizzly. It's autostart and is rated for 1/2 to 1-1/2 hp motors. The motor I'm using it with is 1hp. I got it new for this purpose but it took me a while to get around to installing it. I've probably had it for too long to send it back.

Sounds like backwards wiring is unlikely to have caused the problem. Is that right?

10-14-2013, 03:30 PM
I was thinking rotary (RPC) but I just noticed the title Static Conv.!

Wayne Sippola
10-14-2013, 09:03 PM
Is it the motor or the static converter that's humming? The motor will hum if it's fed single phase power without it turning. If it's the converter, does it have a contactor? If so, the laminated core that pulls together probably has some corrosion on the faces - this will cause it to buzz.

At a guess, the motor is humming because it's not turning, and this is because the start capacitor is either bad or not getting connected - wired wrong / bad connection / dirty contactor points.