What are possible causes of SCF1 motor short circuit faults on the ATV61 and ATV71?


28 September 2021

SCF1 faults on the ATV61 and ATV71.

Product Line:
ATV71 Altivar 71


SCF1 [Motor short circuit]     Short-circuit or grounding at drive output

  • Check the cables connecting the drive to the motor, and the motor’s insulation
    • Using a 1,000V Megger, test the motor and leads
    • Check for tight wiring connections
  • Perform tests via the [1.10 DIAGNOSTICS] menu.​
    • [Diagnostics] -> [Test Procedures] -> Thyristors Test and Transistor Test
  • Run the drive open circuit (with the motor disconnected, OPL turned off, and Motor Control Type set to V/F 2pts) and check the drive's output (T) terminals for balanced voltages phase to phase
    • ​[1.8 Fault Management] -> [Output Phase Loss] -> set to 'No' 
    • [1.4 Motor Control] -> [Motor control type] -> set to 'V/F 2pts'
  • Perform a diode check between U,W,V and PA+ PC-. Then measure between L1, L2, L3 and PA+ and PC-:
NOTE: This step should be performed when no line voltage is present on the drive. Power down the drive before performing this step. 
-Measure (using your meter's diode  scale) in one direction, then swap your leads and measure again
Measure between PA+ to L1,L2,L3 and between PC- to T1,T2,T3 (total of 6 measurements on the input and 6 measurements on the output)
-You should see 'OL' in one direction and a small voltage reading (approximately 0.3-.0.5V) in the other direction