Powermatic start problem

Re: Powermatic start problem *LINK*

Doc Green

The starting characteristics you describe sound like those of a single phase induction motor 100 years ago. But the inverter/motor combination on a 3520 is three phase.

I suspect you have lost one leg of the three phase power going to the motor. The loss of one leg causes the system to revert to single phase.

Just inside the door of the inverter, check the three connections that go to the motor. These are the black, white, and red wires on the right-hand side of the power strip having six terminals. My suggestion is to loosen and then retighten each screw.

I think there are corresponding connections in a box mounted on the motor. Check those as well. (I don't remember the details.)

If this doesn't solve the problem, use an AC voltmeter to measure the voltage between each pair of the black, white, and red wires referred to above. The voltage should be the same for all pairs. Be careful doing this because the voltage is probably in the hundreds of volts. (The inverter should be in the Run mode while doing this, of course, and it doesn't hurt to have the lathe running.)

An equivalent test is to measure the voltages between the black, white, and red wires (one at a time) relative to one of the green ground wires. The grounds are the two left-most terminals on the bottom power strip, which has five terminals. The voltage should be the same for each wire.

If you find the voltages are not the same, the indication is that one leg of the power circuit inside the inverter has gone bad. In this case, you will have to send the inverter out for repair.

Here's a link to a description of the circuitry:


PM Control Circuitry

Re: Powermatic start problem

john lucas

What Doc said is good. I have also found that there can be loose connections inside the inverter that cause wierd problems. Unplug the machine, take off the cover and tighten anything with wires. If all else fails call powermatic.

Re: Powermatic start problem

billkaz

Thanks, Doc, will give that a try.

Bill

Re: Powermatic start problem

billkaz

Thanks John

Re: Powermatic start problem

Dick Hines

Doc knows what he is talking about.

Re: Powermatic start problem

billkaz

Doc, you nailed it, there was a loose wire on one leg of the motor. A simple fix & now back in operation. Amazingly easy, of course once one knows where to look.

Thanks again for reply, another reason to value this forum.

BillK

Between Good and Lucky . . .

Doc Green

I'll take Lucky every time!

~Doc

Re: Between Good and Lucky . . .

Dick Hines

If any one knows the power matic lathe it's Doc