Drives Service & Support > PowerFlex 700 > Fault Finder

Fault Number : 16

Fault Display : Motor Thermistor

Fault Name : Motor Thermistor

Fault Type : None

Fault Description : Thermistor is out of range.

Corrective Action : This fault can be turned on or off using parameter 238 [Fault config 1] bit 7 set to enabled.

The thermistor is checked at the analog in 1 terminals 14 and 15. Terminal 14 is the negative side, while 15 is the positive voltage. Terminal 22 is the +10 volt source, and terminal 10 is the +10 volt pot reference. While the voltage is being measured, the following is figured depending on the measured value:

• Analog PTC OT Set >5v
• PTC OT cleared <4 V
• PTC short < 0.2 volts

The thermistor should be a PTC with 1.8k ohms of resistance around room temperature ambient. The resistance is going to change depending on the temperature of the PTC Thermistor. There needs to be a 3.32k ohm resistor also in the circuit from terminal 10. Remove the resistor from the circuit and make sure there is proper resistance. Also isolate and check the resistance through the thermistor.