ABB ACS800 Fault 2340 Short Circuit
Staring at Fault 2340 on your ABB ACS800 VFD? This guide explains how to troubleshoot motor shorts, check for forbidden output capacitors, and restore your drive safely.
If your ABB ACS800 drive has suddenly tripped and the keypad is flashing Fault 2340 (SHORT CIRCUIT), you are dealing with a critical hardware protection event. This fault indicates that the drive has detected a massive current surge that suggests a direct electrical short between the output phases or to the ground.
Because this fault protects the internal IGBTs (Insulated Gate Bipolar Transistors) from literal destruction, the drive shuts down in microseconds. Here is a human-made, step-by-step guide to help you find the short and get your system back in production.
What Exactly Causes Fault 2340?
The 2340 error occurs when the drive's output current exceeds its instantaneous trip limit. Unlike an "Overload" (which builds up over time), a "Short Circuit" is immediate. The cause is usually found in one of three areas:
- Motor Winding Failure: Internal insulation breakdown in the motor.
- Cable Damage: A nick, crush, or moisture in the conduit between the VFD and the motor.
- Forbidden External Components: Capacitors or surge suppressors installed on the output side of the drive.
Step-by-Step Troubleshooting Guide
1. The Isolation Test (Is the Drive OK?)
The first goal is to determine if the short is inside the drive or outside in the field.
- Disconnect the motor cables (U2, V2, W2) from the bottom of the drive.
- Attempt to start the drive (set it to a low frequency).
- If Fault 2340 returns immediately: The internal power module (IGBT) of the ACS800 is shorted. The drive must be repaired or replaced.
- If the drive runs fine (shows frequency): The drive hardware is healthy. The problem is definitely in your motor or cabling.
2. Inspect the Motor and Cables
If the drive passed the isolation test, you must prove the health of the "field" equipment.
- Visual Check: Inspect the motor terminal box for black soot, moisture, or loose wire "whiskers" that could be bridging the phases.
- Megger Test: Use an insulation tester (Megger) on the motor leads. Check for shorts between phases (U-V, V-W, U-W) and from each phase to the ground/chassis.
- Check Cable Run: Look for damage where the cable enters the motor or passes through tight bends.
3. Check for Prohibited Output Components
This is a common "hidden" cause of Fault 2340 in older plants. VFDs output high-frequency PWM (Pulse Width Modulation) signals. Certain components designed for "across-the-line" motors will act as a dead short to these signals:
- Power Factor Correction Capacitors: These must never be installed between the VFD and the motor.
- Surge Absorbers/Suppressors: These are often found in older motor terminal boxes. They can misinterpret the VFD pulses as voltage spikes and attempt to clamp them, triggering a 2340 trip.
Remedy: If these components are present, they must be removed entirely from the circuit.
Summary Checklist for Fault 2340
| Checkpoint | Action Required |
|---|---|
| Drive (No Load) | Disconnect U2/V2/W2. If 2340 stays, the IGBT is failed. |
| Motor Windings | Perform a Megger test (Insulation Resistance). |
| Output Side | Remove any Capacitors or Surge Absorbers. |
| Terminals | Ensure all motor lead screws are tight and dry. |
How to Reset
- Clear the electrical short (repair cable or replace motor).
- Remove any forbidden capacitors.
- Press the [RESET] key on the ACS800 keypad.
- If the fault triggers again immediately without the motor connected, do not keep resetting it—this can cause a fire if the internal fault is severe.
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