Frequently asked questions

FA242938

01 September 2023

Issue:
SCF4 fault on ATV12 drives

Product Line:
Altivar ATV12

Environment:
All

Cause:
ATV12 drive is powering up with an SCF4 fault.

Resolution:
SCF4 means IGBT short circuit fault.
Possible issues: Internal power component short circuit detected at power on.  The drive may need to be replaced if the fault is coming up on power up. Check for any exploded/burnt electrical components on the drive. Also try running the drive without the motor leads connected and see if the fault persists. 

A static check can be performed on the drive:

Checking The Input and Output Diode Bridges
This test is done using a digital multi-meter in diode test mode to check that the transistors and diodes are not short-circuited. 


ALL TESTS ARE TO BE PERFORMED WITH ALL SOURCES OF POWER REMOVED FROM THE DRIVE

 

• Instrument
  • Use Digit-Meter with a diode scale
• Measurement
  • ​Locate PA+ and PC- input on drive power terminals (should be close to your power connection terminals)
  • Set meter to diode scale
  • To measure Input diodes
    • Place black on positive bus (PA+) and red on L1
    • Get reading and then move to L2 and then L3 
    • When done swap red and black probes and measure again between (PA+) to L1...L3
    • Readings should be OL in one direction and a low voltage reading the other way (Example 0.3v)
  • To measure Output IGBTs
    • Place black on positive bus (PA+) and red on T1
    • Get reading and then move to T2 and then T3 
    • When done swap red and black probes and measure again between (PA+) to T1...T3
    • Readings should be OL in one direction and a low voltage reading the other way (Example 0.3v)

Readings outside of the ranges given would point to damage in the drive.  
The ATV12 drives are not repairable so the product should be replaced.
If readings are within range, the drive is likely fine and the motor and cables should be checked for phase to phase or phase to ground shorts.