Have you ever blown up components in your electronics? Pow! After the smoke clears, it’s charred, it’s black, it has holes in it and worst of all, it doesn’t work. Creative cursing may result from this frustrating situation!
Why did this happen? Is there anything you could have done to prevent this always untimely disaster?
There is more than one answer to both of these questions. Here’s a quick hit list of potential IGBT-busting causes, some preventive measures and a great case-study story:
• Conductive dirt causing stray current paths – keep your equipment clean
• Overheating – usually from a failed cooling fan or excessive buildup of contaminants so keep your equipment clean and practice regular maintenance
• Gating circuit problem (the gating circuit turns IGBTs on and off) – this is most likely caused by age but could be made worse by dirt , moisture, or excessive vibration
• Bad voltage spike or surge – this could mean there are primary power supply problems, ground faults, or a dropped phase
• Wiring short – most likely caused by aging equipment
• Overcurrent draw – can be caused by a physical problem with the machine. Anything that would impede the motion of the machine could cause excessive current because the slower a motor runs, the higher the current. This could include bad bearings on a shaft, something binding the machine, or a sudden stoppage where excess current is diverted through a separate transistor and resistor combination designed to eliminate the current and protect the IGBT. If this transistor or resistor fails, the current feeds back into the IGBT and damages it.
• Shorted motor –- this could mean the windings have shorted, there was a power conductor/wire insulation failure or seized brake causing overload.
As promised, here’s a perfect case-study example sent in by one of our customers, a major U.S. – based global exporter. See the photos of the damaged Mitsubishi servo amplifier and the IGBT that took the hit and literally blew apart. The customer was unhappy and anxious to get their equipment running again.
As it turns out, this particular Mitsubishi servo amp is no longer manufactured and the OEM no longer provides repairs. Not surprisingly, they would be only too pleased to provide a replacement…for almost $3,000! Our electronic repair team quickly identified the damaged parts, made the repairs, and got it back up and running for less than half the cost of replacement. Now that’s a win!
The bad news is that your servo amp may not be working, but hopefully you have a working backup. The good news is that most damaged servo amplifiers are repairable, and just as important, servo amplifiers are usually worth repairing. Let us help you with your industrial electronic repairs!