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Powermatic Glitch

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I've got a powermatic 3520b. The thing has been bullet proof until this afternoon. I hit the stop switch and it took about a minute to spin down. Way longer than normal. When I tried to turn it back on it wouldn't start. After trying some things (yell at it, off..on..off..on..off (a bunch of times like it might make a difference), unplugging...waiting...plugging in and yelling at it some more) without any luck, I pressed the red stop / reset button on the inverter. Everything is back to normal.

Anybody ever experience this? Is this a sign I should have something minor serviced before it turns into something major like buying a new inverter? I didn't notice the lights blink in the shop like we took a power hit or anything, but who knows.

Any and all thoughts / comments welcome.

Ed

Who knows that yelling at equipment rarely solves equipment problems, but still does it because he can't help himself.....
 

odie

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If it involves pain, then the yelling gets louder! :D

I've been known to cuss out a few tools in my day, too!







Sorry, Ed.....don't know about the electrical problem, but I'm sure someone more familiar with your troubles can give some technical insight. If it were me, I'd be inclined to not give it much thought unless it becomes chronic. Your circuit breaker is working properly.......

ooc
 
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I have never had that happen with my 3520b. But on rare occasions, I will turn it on, and nothing happens. I unplug it, let it sit for a few seconds, plug it back in again, and it works fine. I have written it off to being just a nuisance, since it has happened only about 2-3 times in the 5 years I have been using mine.
 
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i agree with the others, sounds like a breaker.

plug a radio, or something like that that is portable and easy to tell if there is power to it, and see if it works.

if there is power to the exact plug in location as it was plugged into, then obviously it is in the machine itself.

are there any breakers on that lathe, itself? my 46-460 delta has a fuse/breaker
 

hockenbery

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Since it did not break to a stop,

The controller lost control of the motor.
controllers normally stop the motor.

Could be a breaker, a broken or shorted wire, plug out of wall, wall socket shorted,

Maybe it was just tired and needed a resest

Good luck
Al
 
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Thanks everyone. There was power to the lathe because the digital display stayed lit and the display on the inverter was working, but it was showing what looked like a "Uo" instead of the usual cryptic display. It's a 220v setup, and the breakers weren't tripped. The only other thing I could plug into the outlet would be my bandsaw, and that would be a hassle to do (cords not long enough and I don't have a 220 extension).

I'm pretty sure it was an inverter glitch. Usually breaking kicks in when you turn the lathe off and it quickly spins down. When it had the problem it very slowly dropped rpms, taking about a minute to reach 60 rpm (I had been working at ~3000 rpm) at which point I grabbed the handwheel and stopped it. Plugging and unplugging didn't solve the problem. Pressing the stop / reset button on the inverter did solve the problem.

It's worked fine the rest of the afternoon, so I'm just not going to worry about it and hope it doesn't happen again. The 5 year warranty is up in June, hope its not an omen. I'll give powermatic tech support a call on Monday when they are back in the office.

Ed
 
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Did the VFD read "Ou" or "Uo". Ou stands for voltage overload. The elements of this type of display screen can not display slanted lines as in k, R, V,etc. Use your imagination. Ou can be caused by input voltage out of range, voltage transients, braking out of control, too large of a workpiece for the braking resistor. Faults are removed by pushing reset button on the VFD. A lightning spike somewhere fairly close could have triggered this fault. If braking was at fault the decel time can be increased by changing the decel parameter. If your are turning extra large objects contact Powermatic for change.
 
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Hi Bill - Thanks for the info. It might have been Uo. I'm going from memory, which is problematic these days. I should have taken a picture of the display. Next time.....if I remember. Of course I hope there isn't a next time.

I was turning a pen barrel at the time, so weight was negligible. I guess some kind of issue with the power company is the most likely culprit. Pressing reset solved the problem. My main worry was whether it was a symptom of a major
problem possibly developing. Doesn't sound like it though, so I think I'm good to go. Lathe worked great all evening with no problems.

Ed
 
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No help from me - but - Congrats

Hi Ed,

Happy Easter to you - don't eat too much rabbit.
Congrats on the pen contest win - I voted for you! You should have won second place also.

I can't help with the electrical issue.
I am an expert at yelling at equipment and more so at the operators of the equipment (autos) on South Florida's highways. Linda always says "You know he can't hear you?".

Our best to you,
Bob
 
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By chance, was the piece you were turning at the heavy end of what you normally turn? And was it well balanced, so you were turning that heavy piece at an higher rpm than you normally turn heavy pieces?

If so, when stopping, the VFD will attempt to slow the piece down by dynamic braking - but if piece is heavy and turning at higher rpm - then VFD will decide it can't dissipate the energy caused by the braking - and protect itself by throwing a fault and letting the piece coast to a stop. And that is fixed by doing a reset.

Nothing is harmed, the VFD was just looking out for itself.

Turners who want to slow heavy pieces from high rpms can add a ballast resistor to the VFD that will allow any size piece to be braked from high rpm.

Not sure if this is what happened to you ...
 
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I've had the same problem that Steve described more times than I can remember. Large blanks will cause this problem to occur when one shuts the lathe down with it going as slow as 400 rpm's. If you slow the lathe down slowly using the speed controller it will prevent it from happening.
Good Luck,
Jack Mincey
 
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It is possible for circuit breakers to go bad. Since your 220v circuit has two breakers it is possible that one is OK thus your display is working but there is not enough juice to run the inverter. Do you have access to a meter to check the voltage?
 
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Thanks for all the input from everyone. Just to close this thread out:

The glitch was a one time event. It hasn't repeated.

I was turning a pen at the time so weight was negligible.

The lathe started up and ran fine (and has continued to run fine) after pressing reset on the inverter.

I'm declaring "Problem Solved", without really understanding what the problem was. But as long as the lathe continues to operate, I'm happy.

Ed
 

Bill Boehme

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The technical answer

As an electrical engineer I get to occasionally see or hear of non-repeatable events such as this and after conferring with a couple of my colleagues about their similar experiences, the best technical explanation seems to be that sometimes things go "bump in the night" or even in broad daylight for no apparent reason and then work just fine as though nothing ever happened after being reset. There are enough transients running around on the power lines (spikes, surges, dropouts, noise, and whatnot) that such an event is the most likely cause. The equipment is rugged enough to handle such transients without having a failure and going through the reset process is the right solution. Anybody with a computer has encountered similar stuff and the "brains" of these controllers are just specialized computers. This phenomena is not limited to electrical and mechanical devices -- sometimes my brain freezes and I need to do a reset. Seems to happen more frequently as I get older. That could mean that my memory is starting to fill up and information is getting lost when my brain is trying to defragment itself.
 
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Ghost

Ed it was probably a ghost in the machine, Or just close to April Fools .
 
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Ed,
My 3520 will do that if I have an extremely large and heavy turning and I shot the machine off with the stop switch. Shutting off the power for a few minutes allows it to reset itself.
faust
 

Bill Boehme

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Ha! Given the size, maybe a chunk of a neutron star would have had enough mass to matter here.

Ed

Everything else being equal, if you were running the lathe at near relativistic speed, the mass of the pen would increase as the square of the velocity. (It might also bring your local power grid to its knees). :D
 
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Everything else being equal, if you were running the lathe at near relativistic speed, the mass of the pen would increase as the square of the velocity. (It might also bring your local power grid to its knees). :D

Hmmmm....maybe that dilithium upgrade to the inverter wasn't such a great idea. Although I never run it faster than 9999 rpm! ;)

Ed
 
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