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


25 October 2022

SCF1 faults on the ATV61 and ATV71.

Product Line:
ATV71, Altivar 71
ATV61, Altivar 61


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 the Transistor test via the [1.10 DIAGNOSTICS] menu with the motor connected.​
    • [Diagnostics] -> [Test Procedures] -> 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 using terminals U/T1, W/T2, V/T3, 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 ABC scale) in one direction, then swap your leads and measure again
Measure between PA+ to T1, T2, and T3.  Then swap leads and test again. 
Next measure between PC- to T1,T2,T3 and then swap leads.  (total of 12 measurements: 6 measurements to PA+ and 6 measurements to PC-)
-You should see 'OL' in one direction and a small voltage reading (approximately 0.3-.0.5V) in the other direction and each set of measurements should be consistent between phases.
-Values outside the acceptable range can indicate damage to the IGBT's or other components in the drive.

Return programming to original settings after testing is complete.