VFD-rated motor cable
First part to price when insulation damage or output-cable leakage is found.
ABB ACS355 Fault 2330 — Ground Fault
Fault 2330 on the ABB ACS355 variable frequency drive means the drive has detected a ground fault condition on the output — significant current is flowing from one or more output phases to earth ground. The drive shuts down immediately to prevent damage to the motor and drive output stage.
Jump to Fix
What Is a Ground Fault on a VFD?
In a properly wired motor and drive system, output current should flow only through the motor windings — not to ground. A ground fault means current is finding a path to earth through:
- Damaged motor winding insulation
- Damaged motor cable insulation
- Moisture or contamination in the motor or cable
- Faulty output wiring
Common Causes {#most-likely-cause}
| Cause | Likelihood |
|---|---|
| Failed motor winding insulation (aged motor) | High |
| Damaged output cable (chafed or pinched) | High |
| Moisture in motor terminal box | High |
| Long motor cable with high capacitive ground current | Medium |
| Drive output IGBT failure (internal fault) | Medium |
| Incorrect fault 2330 trip (ground fault threshold too sensitive) | Low |
Step-by-Step Diagnosis {#diagnosis}
Step 1 — Disconnect the motor cable from the drive
- Power off the drive and wait for DC bus to discharge (minimum 5 minutes)
- Disconnect the motor cable at the U, V, W output terminals of the ACS355
- If Fault 2330 no longer appears on power-up: the fault is in the motor or cable
Step 2 — Megger test the motor
- Using a 500V or 1000V insulation resistance tester (megger):
- Measure insulation resistance from each motor phase terminal to the motor frame (ground)
- Acceptable minimum: 1 MΩ (IEC standard) — above 100 MΩ is ideal
- Below 1 MΩ: motor insulation is failed — motor requires rewinding or replacement
- Test with the motor cable disconnected from the motor to isolate the motor from the cable
Step 3 — Megger test the motor cable
- With both ends of the cable disconnected (from drive and motor):
- Measure insulation resistance conductor-to-ground on each conductor
- Below 1 MΩ: cable is damaged — replace
Step 4 — Check for moisture
- Inspect the motor terminal box for condensate, water infiltration, or corrosion
- Dry the terminal box with a heat gun
- Apply insulating spray if corrosion is present
Step 5 — Check cable length and shielding
- Long unshielded motor cables create capacitive ground currents that can falsely trip Fault 2330
- ACS355 applications: use shielded cable for runs over 30 meters
- Check ABB ACS355 parameter 1601 (Ground Fault) — if set to OFF, the fault indication may be from an internal fault
Step 6 — Check drive output IGBTs
- If Fault 2330 appears with the motor disconnected: the drive output stage may have failed
- Check for shorted IGBT by measuring resistance from each output terminal (U, V, W) to DC+ and DC-
- A failed IGBT shows very low resistance in both directions — requires drive repair or replacement
Fault 2330 Reset
After identifying and fixing the fault:
- Reconnect motor cable
- Reset the ACS355 by pressing the STOP/RESET button or cycling power
- Run a test at low speed first to confirm the fault has cleared
Replacement Parts {#parts}
| Part | Notes |
|---|---|
| Motor (rewound or replacement) | Match HP, voltage, frame, and poles |
| Motor cable (shielded) | Use shielded 4-conductor cable for VFD applications |
| ACS355 drive | If output IGBT confirmed failed |
Need Replacement Parts?
Before ordering, match the drive part to the model number, electrical rating, and failure symptom. Check current prices on Amazon - prices and availability change frequently.
Pro tip: The ABB ACS355 supports a ground fault trip sensitivity parameter. For long cable runs, check parameter 1601 and consult ABB application note AN-14-0046 for capacitive ground current calculations.