One relatively common fault is over-voltage, often shown as “OV” or “OU” or similar, and often with an accompanying description of “DC Link Overvoltage”.
Fundamentally, this fault is in response to the drive’s internal DC bus seeing a voltage higher than the limit specified in the drive settings.
Most of the time, this fault occurs when the drive is attempting to quickly decelerate a high-inertia load; the motor is then overhauled by the load and becomes, in effect, a generator, pushing current back into the drive and recharging the DC capacitors before its DC bus voltage has had time to bleed off.
The generated voltage then adds to the existing bus voltage, causing the overvoltage.
Today we look at overvoltage faults, as we continue with some of the more common faults experienced by variable speed drives, their causes, and some ways to resolve them. Variable Speed Drives (VSDs, a.k.a. Adjustable Speed Drives (ASDs) or, for AC motor control, Variable Frequency Drives...
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