Schneider Electric Altivar Machine ATV320 fault SCF3: Ground short circuit
SCF3 on a Schneider Altivar ATV320 is a ground short circuit error: the drive detected significant earth leakage current at its output. Schneider gives several motors connected in parallel as the typical case.
Diagnose this with AI
Try Free Drive Diagnostic Upload a keypad photo, the fault history or a parameter export from your Schneider Electric Altivar Machine ATV320. InduQT compares the evidence and suggests the next useful checks.
When it happens
- At start or while running
- With several motors on one drive
- After wash-down or in damp conditions
Likely causes and checks
1Motor cable insulation to ground
- Points to it
- Cable runs through wet ducts or has been damaged; trip comes at any speed.
- Check
- Lock out, confirm DC bus below 42 Vdc, disconnect the cable at the drive and megger each conductor to ground.
2Motor winding insulation to ground
- Points to it
- Cable good; motor damp, old or overheated.
- Check
- Megger the motor to ground with it disconnected from the drive.
3Leakage from several motors or long cables in parallel
- Points to it
- Insulation tests good; several motors share the drive output, or total cable length is long.
- Check
- Schneider lists connecting chokes in series with the motor and reducing [Switching frequency] SFR.
4Speed loop or brake settings
- Points to it
- Trips around brake release on brake-controlled axes.
- Check
- Check speed loop and brake adjustment and consider increasing [Time to restart] TTR, as Schneider lists.
Telling it apart
- SCF3 is leakage to ground; SCF1 is a short or grounding at the output. Both point first to the cable and motor.
- If insulation is good and the drive feeds several motors, capacitive leakage is the more likely cause.
- SCF3 needs a power reset unless [Extended Fault Reset] HRFC = YES.
Relevant parameters
| Parameter | Name | Why it matters |
|---|---|---|
| SFR | Switching frequency | Reducing it is a listed remedy for SCF3. |
| TTR | Time to restart | Increasing it is a listed remedy. |
Evidence to collect
- Error history entry for SCF3
- Insulation test results with cable and motor disconnected from the drive
- Number of motors and total cable length
- SFR setting and any output chokes
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