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2000 VFOE Issues

Twister

Plastic
Joined
Oct 6, 2020
Hi There. New to the forum, but I've been an occasional visitor for many years. Lots of knowledge here.
Anyhow, our old VFOE had a dramatic Vector drive failure in June. The machine was happily machining some delrin, there was loud Bang, then all was silent save the spindle winding down. Tripped the 40A breaker at the panel, lots of burnt circuit stink coming from the cabinet. Had the HFO technician test everything, and it was found the Vector drive was toast. He put a new unit in to test the machine and all was ok. That was great until we found out the price of the new V Drive was close to $9kincl taxes for the replacement.
Sent our crispy Drive (Capacitor blew) to a third party recommended by forum members. 3 weeks later we had the machine running again, albeit the spindle was noisy, and getting worse by the minute.
Spindle rebuild. Another month.
Had the HFO tech come back to put the spindle in and run electrical diagnostics, lube tests etc. Found the low voltage CB was toast, so he replaced that. Ran the Spindle Break in program. All was good.
Came in the following Monday, morning, ran a Spindle run in program just to cycle the spindle again. Another loud Bang, then nothing except for the spindle winding down.
This time it tripped the 100Amp main breaker! No visible damage or smell coming from the cabinet though. Ran some resistance tests on the V_drive as recommended, and all was good. Decided to fire the machine up again. No faults. All seemed well.
I ran the Spindle Run in program again yesterday, and it cycled completely. the machine than sat, power on for several hours, then the Bang/breaker trip occurred again.
Essentially, I'm wondering if anyone has had these symptoms, and can share their thoughts.
Whew!. That is a lot of typing!

Thanks in advance

Tom
 
Wild guess - you could have a short in the "energy chain" (the flexible electrical conduit that goes from control cabinet to the spindle motor), which at some point in movement allows two cables (or a cable to ground) to short out.

The machine's twenty years old, with 100's of thousands of cycles on the head moving up and down. Insulation grows old and brittle, or wears on a surface, and suddenly you wind up with a short and banging breakers.

Ask your HFO if they've seen this before, or if there's similar areas within the motor or cabinet that have caused short failures. Even circuit boards themselves can break down, but I'd look at moving cables first.

I would not run the machine until this is resolved, unless you REALLY have to...
 
I'd hazard the shorted cable guess. IGBT are low resistance, a short in the cable is going to pass through to the supply to a certain measure.
 








 
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