thoughts on failed minimax saw motor

[joe milana]

Motor is at the shop. Waiting for diagnosis. Once again, SCM's "over the phone" diagnosis was : If the motor was run for long periods of time with a bad run cap, then the motor would run "out of phase", and amperage would be excessively high, causing winding failure.

[joe milana]

Just heard from the guy. Motor shop said "motor starter" in the motor was dirty. I'm assuming he meant centrifugal switch. Said windings were fine. He re-installed the motor & said it's pulling 20amps at idle, which SCM says is high. Motor shop said is fine.
I asked if he ever checked the contacts in the mag starter, and he said no. He didn't know the saw had one. Once again, it's 5hp single phase.

[David Kumm]

Life is good- for now. Dave

[joe milana]

Any idea if that saw has a mag starter?

[joe milana]

Motor badge
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[Larry Edgerton]

Unplug the saw when it is running, plug it back in, if it starts it does not have one. I had a single phase Minimax that did not.

[David Kumm]

Usually a mag starter will have momentary contact buttons and a manual will have maintained contact ones. What Larry says to test. Dave

[joe milana]

thanks. It has momentary switches. I'll have him do the unplug test. Cant believe SCM or motor shop has not said a word about mag starter.

[Mike Kreinhop]

My 3-phase SC2 has a Siemens 3RV2011-1HA10 circuit breaker that serves as the On-Off switch and provides the thermal overload protection for the motor. It also uses a Siemens 3RV2902-1AV0 Undervoltage Release to enable the breaker when everything is set up correctly or to trip the breaker when the emergency stop button is pushed or the side guard is opened. Unlike a classic motor starter circuit that uses push buttons, a contactor, thermal contacts, and a latching contact in series with the contactor coil, the Siemens circuit breaker has a mechanical latch that works when the knob is turned, unless the Undervoltage Release prevents the circuit breaker from closing. This is the main reason why relocating the start switch or adding a remote switch to the Minimax is not possible without replacing or bypassing the factory installed circuit breaker...which is what I will eventually do.

I suspect the S315 has something similar. When power is applied to the saw, and all of the safeties are in the normal mode, you should here a "click" as the Undervoltage Release activates to enable the circuit breaker. If you start the saw and unplug it, the saw will stop. If you then plug it back in, it will not restart because the Undervoltage Release tripped the circuit breaker in the saw and it must be manually reset by turning the knob to the Off position before you can start it again.

[joe milana]

Thanks for that. That's exactly what this saw has. Now to determine if it is serviceable. ie. Can the contacts be accessed & cleaned?
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The saw is currently pulling 20amps unloaded (tested with Klein ring meter). SCM says it should pull about 8-9amps unloaded & is still convinced the motor is bad. I suggested he "hardwire" the motor directly to the circuit. bypassing all the saws electrics & measure then. That will give us a baseline & rule out any other component of the saw being bad. We'll see what happens.

[Rod Sheridan]

Hi Joe, is the run capacitor working?

With the saw running what's the current in the run capacitor?

Regards, Rod.

[Dan Friedrichs]

Joe, I may be seeing it wrong, but I don't think your picture of that starter is what Mike is talking about. Yours looks like a regular magnetic contactor.

Mike's probably looks something like this: https://mall.industry.siemens.com/ma.../3RV2011-1HA10

[joe milana]

Hi Joe, is the run capacitor working?

With the saw running what's the current in the run capacitor?
Regards, Rod.

Not sure how to check current in the run capacitor. Motor shop said caps either work, or they dont, and this one is fine.

Joe, I may be seeing it wrong, but I don't think your picture of that starter is what Mike is talking about. Yours looks like a regular magnetic contactor.

Mike's probably looks something like this: https://mall.industry.siemens.com/ma.../3RV2011-1HA10

Thanks Dan, yeah, I downloaded some info on the part shown, and I was thinking it looked like a normal contactor as well.

He "hard wired" the saw to the source, bypassing the saws electricals, and it still pulls 18amps at no load. Scm says it should be ~9.

[Rod Sheridan]

Not sure how to check current in the run capacitor. Motor shop said caps either work, or they dont, and this one is fine.




Thanks Dan, yeah, I downloaded some info on the part shown, and I was thinking it looked like a normal contactor as well.

He "hard wired" the saw to the source, bypassing the saws electricals, and it still pulls 18amps at no load. Scm says it should be ~9.

Hi, to check the current in the run capacitor use a clamp on AC ammeter, around one of the capacitor wires.

Is the capacitor the correct value? Wouldn't be the first time I found the wrong run capacitor installed...........Regards, Rod.