Drives Service & Support > PowerFlex 700 > Fault Finder

Fault Number : 9

Fault Display : Trnsistr OvrTemp

Fault Name : Transistor OverTemperature

Fault Type : 1 - Auto-Reset Run

Fault Description : Output transistors have exceede their maximum operating temperature.

Corrective Action : This is an uncommon fault. The transistor temperatures are monitored by an internal device within the transistor itself. This is not a device external to the transistor.

Possible causes of this fault are transistors being improperly mounted to the drives heatsink. A lack of thermal paste or thermal pad, or improper application of such thermal devices may cause the transistor to overheat. Improper torque on the mounting screws, or mounting screws coming loose can cause an improper bond between the heatsink and the thermistor, resulting in an overtemperature situation.

A localized blockage in air flow across the heatsink may also cause an overheating condition. An example would be a foreign object being pulled in by the heatsink fan, and blocking part of the heatsink from the fan. This would create a vertical column in the heatsink that would not receive airflow from the heatsink fan.