Motor Electrical Issue

Re: Motor Electrical Issue

John in NM

Probably its a relay or contactor in the unit that is arcing as it ages. My air compressor was doing that - likewise fine on a 20 amp circuit except for the one problem. Initially I recall it doing so on startup mostly, towards the end it was on shut down - but never in the middle of running.

Re: Motor Electrical Issue

John McGaw

An easy first troubleshooting step would be to try it on a different circuit or to swap breakers between circuits. That should tell you if the original breaker is weak. I understand that there are specialized circuit breakers meant for motor circuits which are tolerant of startup current surges although I haven't used them myself.

Re: Motor Electrical Issue

Bill Howatt

I'd try it with a different breaker. They can vary. The startup surge is what is likely the problem and it can be for a brief moment about 6 times the full-load current.

I think all breakers are rated HACR which means they will tolerate brief motor startup surges. If you have a long run of 12/2 from your panel it could be dropping the voltage a the motor when the startup surge happens. Try an outlet closer to your panel.

Are the motor and other bearings in good shape. It is amazing how a little extra drag on startup affects the time of the startup surge and can cause this type of problem. Everything should be free and smooth but just how free depends on the device.

Bill

Electrical

Mark Mandell - Gone Round In New Jersey

Outlet is No. 1 on the circuit, 10' from the panel (20' of wire), with nothing else drawing on the 20 amps. Doesn't happen all the time. Only seems to trip if the conveyor is turned on first and then the sanding drum.

This NEVER happened when it was in the basement with a longer run to the panel.

I can string a heavy extension cord to pull from a different circuit, but that would mean more voltage drop, minuscule thought it might be.

Looks like it's time to open up the switch box and check for arcing to the ground. All of the 120v circuits in the shop are required to be GFCI so they're less tolerant to either a spike or an arc.

Re: Electrical

Bill Howatt

Does the conveyor motor have brushes? The manual I found indicates it is DC so it may have them. Now the other thing concerns the breakers - are they GFCI only or are they both Ground Fault and Arc Fault in the same package. It appears combos are the way things are going but I can't say I'm that familiar with it.

If so, that could be the problem since Arc Fault don't like arcs and have been a known problem with vacuums, hair dryers, etc.

At least you know how to avoid the tripping with the starting order.

Bill

Re: Electrical

Walter Ahlgrim

Will you please post a photo of the tag on the large motor?

Was the machine on a GFIC circuit in the old shop?

Is it possible the electrician installed an arc and ground fault breaker?

An interesting test would be to measure how low the voltage is dropping when the motor is starting.

It is possible a GFCI breaker is not tripping for over current but tripping for a ground fault some brands of breakers will flash a blinking red LED to indicate why it tripped.

Walta

Re: Electrical

Mark Mandell - Gone Round In New Jersey

Will you please post a photo of the tag on the large motor?

Have to be later

Was the machine on a GFIC circuit in the old shop?

Nope

Is it possible the electrician installed an arc and ground fault breaker?

No. I'm the electrician. GFCI is done with the first outlet which has not tripped. This has to be an overdraw issue with the big motor

An interesting test would be to measure how low the voltage is dropping when the motor is starting.

Don't have the equipment for that kind of test. I have three other smaller 120v machines on the same circuit. I may try turning them all on (except the sander) to see if I've got a bad breaker.

It is possible a GFCI breaker is not tripping for over current but tripping for a ground fault some brands of breakers will flash a blinking red LED to indicate why it tripped.

No GFCI breaker installed. 1 GFCI outlet as first in line for each 120v circuit. Breaker tripped but not the outlet.

Have a call into JET to see what they have to say.

Thanks for the thoughts

Re: Electrical

Bruce, a MN Galoot

Can it be rewired for 220? I had a similar problem with a compressor, the breaker should have easily handled the inrush current, but it tripped more than half the time at startup. The electrical inspector was looking at wiring on my new addition and I asked him about it. He said that particular brand of compressor had those problems and suggested I have it rewired. Haven’t had a problem since.

No Rewiring

Mark Mandell - Gone Round In New Jersey

Specifically prohibited. The gear motor running the conveyor belt won't take it. I suspect you'd have to set up 2 discrete circuits with different voltages.

Re: No Rewiring

William Duffield

Don't they do that all the time with electric ranges, in which the clock runs on 110 and the elements on 220? You would have to wire it 12-3 instead of 12-2 and change the plug. This is a question, not advise. I am not an electrician, nor do I play one on TV.

Re: Motor Electrical Issue

Larry Clinton At Frankfort, (Central) Indiana

Quite likely nothing is wrong. You just need to change to a delay breaker that is built for motor starting. From your description, this only occurs when the other motor is already running. This means that there is already some current draw on the line. Many motors draw high current when starting, when you add the load from the running motor to the starting current the breaker is tripping.

The delay motor starting breaker is meant to allow this for a few seconds, but will open if excessive current is drawn.

I would purchase and install a 20 Amp breaker rated for motor starting - Almost every electrical supply house will stock them.

Could Be

Mark Mandell - Gone Round In New Jersey

the way to go, although I'll look into replacing that breaker with a motor-friendly version.

Bugs me since it always ran fine in the basement shop even if though it would trip the breaker if the drum got stalled during a pass.