Rotary Phase Converter not working...

Hello All,
My 7 year old RPC stopped working early this week. Its a 7.5 HP RPC that I use to run my Lathe & Bridgeport Mill.

When I flip the switch, all I hear is a loud humming sound coming from the idler motor. My first thought was one or more of the start capacitors must have gone bad. So, I pulled the cover off the converter and found where two of the 3 start capacitor's had been leaking with crusty stuff coming out of one end of it. I just got through replacing both capacitors with exactly the same spec replacements -- no dice. Still hearing a humming sound.

There are only two other components in this converter -- 2 tin covered Run Capacitors and a Relay Switch? Could the problem be in the relay or run capacitors? Or is the problem specific to the idler motor? With the power off, i was easily able to turn the motor by sticking a screwdriver through the vent hole in the end so I know the problem isn't due to the motors inability to turn freely.

Any ideas on how to troubleshoot this are greatly appreciated!!

-Swarf-Sweeper

Okay this weird. I took the relay out and shook it around real good, rapped on it a couple times and put it back in. RPC fired right up and did so 10 to 12 times without issue. I did see blue electrical arcing across the face of the relay. Man -- this stuff can kill ya if your not careful!

I'm guessing arcing across the relay is not good...comments?

Thanks

Stuck contacts on the potential relay?? It's been working for years... so just replace it.

One set of contacts not closing/dirty. They don't work on two of three phases.

Timw said:

One set of contacts not closing/dirty. They don't work on two of three phases.

Click to expand...

+1

Either file the contacts or (preferably) replace the relay.

I may pull that relay apart and see what's going on inside. I may file the contacts as you suggested for now, and order a replacement online.

Thanks!

-ss