Popping circuit breaker w/ TS

[Don97623]

Hi

I've got a Rockwell Contractors saw which I recently bought. It's got a 1.5HP,

15A (@115V) original motor on it. The saw has seen a fair amount of use.

There doesn't seem to be any significant drag on the system, the motor, belt & spindle seem to turn fine.

However, just about 50% of the time I turn it on, the circuit breaker trips. When it trips, I can just reset the breaker, then turn on the saw and it will always start the second time. If I shut it off, the next time I try to turn it on (warm or cold), it will almost always trip the breaker.

I originally had it plugged into a 15A circuit, and figured the starting current was just a little high. I had been meaning to add a power circuit to the basement, so I added a 20A circuit, and still have the same problem.

Does this mean the motor is bad, or are there soft-start options for these machines, or what?

I could probably wire it up for 230V, but I'd like to have it remain somewhat portable.

Thanx.

Don

[Greg O]

You should not have any problems running this motor on a proper 20 amp circuit. Sounds like a bad start winding switch to me. Most single phase motors have a centrifical switch that energizes the start windings for a second when you turn on the motor. The switch contacts get dirty over time and fail to make good contact. If your are comfortable doing it you may be able to take the motor apart and clean the contacts with some fine emery paper. If it is an open motor you could just try to blow it out well with compressed air, it is possible that some dust is hanging up the start switch too. Also it is possible you have a bad connection some where too. Greg

[Andy Dingley]

I've no idea about US electrics....

But here in the UK we have circuit breakers that are either "Class B" or "Class C". B is the usual domestic sort, C is a little slower-acting (although the same current rating). if you have big motors or welders, you need a class C to avoid this nuisance tripping.

[Dave W]

This may be totally off the mark, but here goes. I had a similar problem with a small 120 volt planer. After looking at every possible problem, I found that the plug was just barely engaged in the receptical. Pushed plug in and problem solved. Dave

[Lars S]

You may also need to replace the breaker. I have found that once a breaker goes a half dozen times, it becomes much more load sensitive. Your breaker may be worn out. They are usually easy to replace -- just pop in a new one.

Lars

[John Girouard]

If you are using an extension cord, try using a shorter one, one with thicker guage wire, or if possible, plugging the tool directly into the wall socket. Worked wonders for me just last week.

-John

[mac davis]

VERY true! I bought a "super duper" 12 gauge cord with triple outlet and a 15 amp breaker on the plug for yard work and stuff... worked great until I used it for my compressor one weekend, and after the compressor popped the breaker a few times, even the leaf blower started popping it... had to chop the plug off and put a "normal" one on..

[Don97623]

This has a 15' long, 12-gauge cord on it, so I don't really think that's it.

I pulled the back of the motor off tonight, and located the centrifugal switch arrangement for the capacitor. My take on how this works is: When the motor is off, the centrifugal "clutch" presses against the switch, closing the 2 contacts, which feed the capacitor. When the saw spins up, the clutch pulls back, opening the contacts and taking the capacitor out of the circuit.

I cleaned the contacts and pulled the contacts up slightly to make better contact, but when I reassembled and tried to start it (no belt attached), it immediately popped the breaker. Next try it spun up ok, and I did get several starts, but it still pops the breaker often (though maybe not quite as often as it did before.) Maybe another, better cleaning is in order. I'm not sure how to check out the capacitor, but that could be a problem. I'll also see if I can verify continuity through the switch when everything's assembled (has to be assembled for switch contact to be made.)

I definitely hear the "clutch" plate snap back into normal mode and rub against the switch contacts once the motor slows down, so the mechanical part seems to be working ok.

Any other thoughts? If another round of playing doesn't work, I'll find a local motor rebuilder & see if they can fix it reasonably cheaply.

Thanx, Don

[Don97623]

Thanks for all the other suggestions - I didn't see them from the AOL newsreader - just saw them after looking at the thread through Google.

As far as the circuit breaker & receptacles go, the problem started on an old

15 amp circuit, but it's now on a brand new 20 amp breaker and all new wiring, so I doubt that's it - not that I couldn't have gotten a bad breaker, of course. I'll also check all my connections in the motor & switch. Does anyone know where to get a wiring diagram for a Rockwell motor? I think the diagram which is usually inside the cover plate was either missing or illegible. When I got the saw, the person I bought it from had disassembled it in order to get it in the car, but had taped up the wires so it was pretty obvious how it should be hooked up, but it's possible I got a wire or two in the wrong place.

Don

[Dan]

On Sun 28 Nov 2004 10:04:19p, [e-mail] (Don97623) wrote in news: [e-mail]:

My Grizzly pops the breaker something like one time in ten at powerup. I don't think my motor or yours is bad.

I'm leaning towards getting a slow-blow breaker. If I remember those electric motor classes right, it's not unusual for an induction motor to pull a lot of amps at the start, then drop. You need quite a bit of power to get all that weight moving.

[Lew Hodgett]

Sounds like you may have a defective cap.

Try the following:

1) Remove cap. 2) Spin rotor and apply power.

If motor comes up to speed without tripping c'bkr, replace starting capacitor.

Good luck.

BTW, a 1P-20A is quite suitable with a #12 wire.

HTH

Lew

[Robert Galloway]

A. Replace the breaker. This one may just be a little "too" sensitive" B. Attach the saw to a 20 amp circuit. You're cutting it a little close. C. Rewire for 220 volt. End of problems.

bob g.

D> Hi

[mac davis]

what we used to do in the "old daze" was make up a box to plug the saw into that had a light bulb socket in the circuit with a "slow blow" fuse the same amperage as the breaker or main fuse.. seemed to help in most cases..

[rcook5]

IIRC you can get slow blowing breakers for applications like this. We had to get one installed in our service panel when the pool pump motor decided it wanted to trip the breaker every time it came out.

Check with an electrical supply house.

--RC

Sleep? Isn't that a totally inadequate substitute for caffine?

[Prometheus]

Funny thing about breakers is that while they look like little switches, they don't tend to work like them. I've found that once you trip one once, you may as well just replace the sucker, because it's going to trip again with less provocation and greater frequency as time goes on. Could be there's nothing wrong with your saw, it might just be a touchy breaker- is your saw the only thing plugged into that circut, or did you genuinely overload it the first time by running too many things at once?

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