Capacitor Fault

Is there anything in the way of specific information available that might help the forum get a start on this?

I see exactly your problem.

Indeed. That is the problem.

...which would explain an overvoltage at the external capacitor, and its early demise. GA.

Yep, another likely ESO failure.

Good morning JRaef,

Some of our older GE & Toshiba VFD units with analog speed feedback do have capacitors on the motor side of the drive.

The newer vector drives do not.

Maybe the OP is dealing with older equipment.

Replying to Comment by SHOCKHISCAN: "Good morning JRaef, Some of our older GE & Toshiba VFD units with analog speed feedback do have capacitors on the motor side of the drive. The newer vector drives do not. Maybe the OP is dealing with older equipment."

Maybe, although this is still suffering from a lack of attention to detail. Most likely you are seeing older Current Source Inverter drives or six step drives that used GTO Thyristors as output power devices, they often needed tuned capacitors on the load side of the drive as part of the necessary circuit design to make the GTOs turn off. That technology is now long gone. Even modern CSI drives no longer use GTO Thyristors.

Or another RTFM situation...

Or burned by an "energy saving" company/consultant?

How about that for global warming?

Dear Mr.ibrahim1988,

Your question does not indicate, like Capacity, Whether the Capacitor is before VFD or after VFD, level of Harmonics Filtering, Earting of VFD etc. Pl. give the factual ground reality. Then only CR4 MEMBERS can suggest a remedy.

DHAYANANDHAN.S

I would suggest you look carefully at the drive regeneration control circuitry.

The drive must have the means to discharge the high voltage created by the collapsing motor field regeneration when the drive supply power is removed and the motor leads are open-circuited.

If/when this voltage exceeds the insulation rating of the capacitor it will penetrate through and cause the capacitior to fail.

You should have either:

1. A dynamic grid resistor bank that is switched into the motor lead circuit automatically when the drive output contactor is opened.

or

2. The drive circuitry will have regeneration control circuitry that will use the secondary bridge components for dissipation of the voltage.

Start by reviewing the drive instruction manual to identify which type of circuitry is present.

If the drive uses internal regeneration control you must not allow any personnel to attempt repair unless they are fully trained and competent.