PM1030 tripping breakers on startup

[r-mm]

This behavior persists with and without the drive belt installed. It also persists whether I turn the machine on with the pot at zero or at any other speed.

Turning the machine on and off repeatedly produces the trip once every 20 or 30 times it is turned on.

 

[r-mm]

To be more scientific about this I counted starts before trip and got the following results

12
12
14
3
12
9

On the last one I waited at least 30 seconds before starting each time to make sure there wasn’t a heat buildup or somesuch

I think it has Stuxnet.

 

[GunsOfNavarone]

Alright...it worked fine before, this started out of the blue? You checked all electrical connections? Is there any small remote chance a small chip got into motor? Is it possible your breaker is bad? It's quick/easy enough to snap it out of there and pop in a new one. Man, I feel for you. Electrical can be frustrating. Where's that Bill Hudson guy when you need him?

 

[GunsOfNavarone]

This is Grizzly, but I assume they are basically the same. These son of a guns are notoriously problematic with the PM's. I promise to stop spitballin' after this!

 

[erikmannie]

I have a PM-1030V, and I only press Start (actually a green button) when the pot is all the way down.

A (newer) PM-1030V will never start if the pot is turned up at all.

Would your breaker ever trip if you always had the pot turned all the way down when you press Start?

After owning the machine for a year, I have gotten into the habit of turning the pot all the way down before I press Start.

 

[r-mm]

Thanks for the junction photos - I will have a friend help me position the machine so I can safely check both. Those at the motor especially I did not know exist.

Erik - yes please see my post above, I tested both starting with pot down and pot not down with same result.

 

[G-ManBart]

Thanks for the junction photos - I will have a friend help me position the machine so I can safely check both. Those at the motor especially I did not know exist.

Erik - yes please see my post above, I tested both starting with pot down and pot not down with same result.

I'm not familiar with your machine, but the title caught my eye. I experienced something like this with a welder recently and posted about it on a welding forum. A couple of the guys there are welder repair techs, so really experienced electronics pros....they pretty much nailed it. In my case I was temporarily running a machine on a breaker that was on the small side. I found that if I flipped the power switch slowly on the machine (either off or on) or sort of fumbled while flipping the switch it would sometimes trip the breaker. I could run the machine really hard, well over the current draw that the breaker was rated for and never get a trip....it was just when flipping the switch. I could power the machine on and off ten times and it might trip once...had me really baffled.

The experts said that the short version is that you get an arc across the contact points when the switch moves, and if you do it slowly, the arc happens when the gap is bigger. That increases the voltage, but the circuit resistance stays the same, so the amperage goes up...it's an amperage spike that was tripping the breaker on a marginal circuit. There is always an amp spike when powering a circuit of that style anyway, so the extra spike from the fumbled switch movement was all it took.

I only mention that because it might be worth checking the switch and related wiring...something loose could be just enough to cause a problem.

Good luck!

 

[r-mm]

Oops posted to wrong thread. In process of checking the switches

 

[r-mm]

Thanks for posting this - extremely useful.

Last night I opened the machine up and removed/retightened every non hard wired connection. I did not see anything untoward nor any signs of arcing. I (carefully) turned the machine on and off with the electronics all exposed to view with the lights off so I could look for arcing. I did this until I got a trip but saw no arcing.

The on/off switch and various safeties do not carry current, I believe they all supply the coil of the contactor. I say coil I don't know if thats the right phrase, I am more familiar with relays. If the arcing you mention is to blame, is it fair to suspect the contactor, which appears to be a Seimans brand?

I'm not familiar with your machine, but the title caught my eye. I experienced something like this with a welder recently and posted about it on a welding forum. A couple of the guys there are welder repair techs, so really experienced electronics pros....they pretty much nailed it. In my case I was temporarily running a machine on a breaker that was on the small side. I found that if I flipped the power switch slowly on the machine (either off or on) or sort of fumbled while flipping the switch it would sometimes trip the breaker. I could run the machine really hard, well over the current draw that the breaker was rated for and never get a trip....it was just when flipping the switch. I could power the machine on and off ten times and it might trip once...had me really baffled.

The experts said that the short version is that you get an arc across the contact points when the switch moves, and if you do it slowly, the arc happens when the gap is bigger. That increases the voltage, but the circuit resistance stays the same, so the amperage goes up...it's an amperage spike that was tripping the breaker on a marginal circuit. There is always an amp spike when powering a circuit of that style anyway, so the extra spike from the fumbled switch movement was all it took.

I only mention that because it might be worth checking the switch and related wiring...something loose could be just enough to cause a problem.

Good luck!

 

[G-ManBart]

Thanks for posting this - extremely useful.

Last night I opened the machine up and removed/retightened every non hard wired connection. I did not see anything untoward nor any signs of arcing. I (carefully) turned the machine on and off with the electronics all exposed to view with the lights off so I could look for arcing. I did this until I got a trip but saw no arcing.

The on/off switch and various safeties do not carry current, I believe they all supply the coil of the contactor. I say coil I don't know if thats the right phrase, I am more familiar with relays. If the arcing you mention is to blame, is it fair to suspect the contactor, which appears to be a Seimans brand?

I just took a quick look at the wiring diagram for your machine and you may be on to something there. I guess it's possible there's an arc inside the switch that isn't visible, but it may well be the contactor. I'm far from an electronics expert, but the similarity to the welder situation only being when powered on/off doesn't seem like a coincidence. In the welder full current goes through the switch, so it's pretty different....and an expensive switch!