Strange electrical event?

[Larry Edgerton]

I was moving some stuff around in my shop and had to put a longer cord on the shaper. When I finished I flipped on the converter and I got a smoke show. Instantly! You could hear it.

So I shut off the converter switch quickly, but there was too much smoke to see where exactly it came from. As the only thing I had changed was the cord I took it all apart to check connections, all looked good with no sign of burning. I checked the cable for breaks and it was good. I checked the wires from the box to the main cutoff that shuts all down and they were good. Looked all over for any sign of burning, could not find any.

The main shutoff was on but the emergency stop button on the start stop panel was off. Found a few connections that were a touch loose, but not bad.

It blew the 50 Amp fuse on one leg of the switch downstream of the converter, and it blew one breaker in the control panel. I checked all I knew how to check and checked a lot I do not but could find no damage. So I turned it back on and both motors fired up just fine, even threw a piece through each spindle to see how it was under load, no problem.

I'm really confused. I am trying to find something that does not seem to exist, but where the heck did the smoke come from and what blew the fuse?

I have work to do and will be running it tomorrow, but this has me spooked a bit. Oh, in case you are confused, this is a double spindle unit.

I checked the converter and I have a 30V swing from high to low. I have been trying to get some one out here to work on it but has not happened yet. Thinking Phase Perfect....

Thoughts? Don't get to crazy on your explanation, I am not good at this stuff so when someone tries to impress me with their knowledge and forgets who they are talking to, well, you know..........

Thanks, Larry

[John K Jordan]

Looked all over for any sign of burning, could not find any.


You've probably done this, but if not did you try locating the smoke source by smell? That has worked for me on occasion.

JKJ

[Larry Edgerton]

That was the first thing I did John. Opened up the control box as that scares me the most, then the switch panel on the front, main shutoff box and then took the back panels off. All the wires are run in flex, so I tested everything before the 4 magnetic starters as they would not have been powered up. Continuity checked on all of them but I did not pull them out of the conduit. I did check wire to wire on the same end to see if two were touching inside the conduit, nope.

Strange thing is it blew a 50 and now works? Voltage spike?

[Bradley Gray]

Strange, Larry, Could there have been a stray strand or two of cord wire that crossed poles then burned up to fix itself?

[John K Jordan]

Strange thing is it blew a 50 and now works? Voltage spike?

I'm assuming the smoke was in the vicinity of the machine and starters. ?

One strange thing happened to me once. As I unplugged the power cord to a lathe I got a bright flash, sound, and smoke and popped a breaker. It "turned" out when I was turning some brass on my wood lathe one tiny strand of brass must have landed on the top of the plug behind the lathe. Upon unplugging, it fell in the gap between the plug and the receptacle and shorted across the plug terminals. Evidence in this case was the color of some smoky deposits on the plastic receptacle cover.

I've also seen a single stray strand of stranded wire short and vaporize, destroying the evidence! Could that be a possibility where the new cable was connected?

In your case where wires are run in flex, I'd might try powering up then flexing each length in case something might touch intermittently.

JKJ

[Larry Edgerton]

I am thinking that may be the case, the eyes are not what they used to be. Does that make smoke?

[Andrew Hughes]

The only time I've had electrical smoke was from the capacitor on my dust collector I forget if it was the run or start.
I sorta remember it still turned on a handful of time before it died.
Good luck.

[Dan Friedrichs]

What do you mean by "converter"? What is the power source (1-phase or 3-phase), what does it run through between the main panel and the motors, etc?

[Carroll Courtney]

When using a converter one leg of power will measure around 190volts or more or what is called the generated leg.If that leg went to any of your control voltage then that may explain what happened.You have to make sure when making up a new cord that the generated leg of power goes to the motor only and nothing else.I'm guessing-----Carroll