Frequently asked questions

FA242938

28 September 2021

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

For Altivar Drive up to 25hp

• 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 readings 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 diodes
    • Place black on positive bus (PA+) and red on T1
    • Get readings 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)

For Altivar Drive over 25hp

• Drive uses SCRs on the positive input bridge and diodes on the negative. For the Output Bridge its all diodes.
• Instrument
  • Use Digit-Meter with an ohm and a diode scale
• Measurement
  • ​Locate PA+ and PC- input on drive power terminals (should be close to your power connection terminals)
  • To measure Input SCRs and diodes.
    • Set meter to ohm scale
    • Place black on positive bus (PA+) and red on L1
    • Get readings 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 at least 50kohms.
    • Set meter to diode scale
    • Place black on positive bus (PC-) and red on L1
    • Get readings and then move to L2 and then L3 
    • When done swap red and black probes and measure again between (PC-) to L1...L3
    • Readings should be OL in one direction and a low voltage reading the other way (Example 0.3v)
  • To measure Output diodes
    • Place black on positive bus (PA+) and red on T1
    • Get readings 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)