Dead Buffer Starter

[SteveHGraham]

The starter on my 3/4 HP buffer refuses to work. It clicks when I plug it in, but that's it. No hum from the motor. Spinning the shaft doesn't help.

Any clues?

I guess I should just get rid of the starter.

[tornitore45]

Click may be a relay. Relay may not pull completely to close the contact. Take it apart an poke around.

[SteveHGraham]

Thanks. That's a start.

The letter "M" is on the front. Trying to figure out what brand that is.

[SteveHGraham]

I didn't have this thing until recently, but now I can't live without it.

[SteveHGraham]

Opened it up. It's a Klockner-Moellner PKZ01-06NA. Not user-friendly to work on. It is now bypassed. I have buffage again.

[Patio]

That starter was also the protection for the motor.
There is a company that I do work for, that has a buffing room. Someone had put to large of heaters in the starter, for the size of motor they were using. The workman was getting it done, to the point that the wires in the motor base would melt down. Then they would make contact with the case and trip the GFI protected, 4,000A main breaker, for the entire plant. Once they had done it twice, they called me. They ordered the proper heaters and larger motors for the buffing wheels.

Most of the things that we deal with, were designed by engineers for safety, when you start bypassing part, it could end up ruining your day, or worse. JS

[SteveHGraham]

This is a simple 3/4-HP motor, just like the ones that are sold by the thousands every day by Home Depot and Harbor Freight, without external protection. It will be fine whether I replace the starter or not.

If it were necessary to put a new protection device on it, then I would also have to put them on my planer, band saws, jointer, dry saw, miter saws... everything. No one does that.

[SteveHGraham]

I believe it's there because the buffer was expensive, and because it belonged to a school, where kids were likely to do stupid things with it.

[spro]

Read Patio again.

[liveaboard]

Steve has a point; some machines come with protection relays, some don't. Mostly under 1hp don't, and over 1hp do.
My drill press has one, my lathe does not.

The relay is to protect the motor from overheating + melting, users are protected by the breaker or fuse.
I've only had a heat relay trip when something was grossly wrong, like a blown capacitor or jammed shaft.

I prefer to have the heat relay, but if it costs money and time, how much is it worth for a 3/4 hp motor with 1 user?

[Patio]

The way I understand it is, some motors have an internal heat protection, and some do not. Those that don't have use starters with overload heaters.
3/4 hp motor on 115V has a full load current of 13.8 amps. If you have this on a 15A breaker you are not to far off, if it is on a 20, you can run it till it burns up. The same motor has a locked rotor current (something jams the motor and stalls it out), of 82.8A.
When I had my SB heavy 10, it did not have any starters or OL heaters on a 3/4hp motor, and I never had a problem with it.
The information is just to help one better understand the risks and where they come from.

[SteveHGraham]

This motor is rated at 4.6 amps. It surely has thermal protection. Terrible Chinese motors have it, and this is a nice Baldor.

The starter box is rated at 6 amps.

You can look the buffer up. It's a 332B.

The starter was balky from the day I got the buffer. It's nice not having to try two or three times to turn it on.