Short circuit

What does Short circuit mean?

The drive system includes protective measures against short circuits, though to a limited extent, as per EN 61800-5-1. This fault indicates an abnormal current path, potentially causing excessive current flow and damage to internal components or connected wiring. Fault acknowledgement is necessary to clear this condition and resume operation.

• Short circuit between motor phase leads (U, V, W) due to damaged cable insulation or faulty motor windings.
• Short circuit from a motor phase lead to the protective earth conductor, often caused by moisture ingress into the motor terminal box or conduit.
• Internal power switching device (e.g., IGBT) failure within the drive's output stage, creating a direct short across phases or to DC bus.
• Control circuit wiring short to ground or another signal, causing excessive current draw on the drive's auxiliary power supply (e.g., 24VDC output overloaded).
• Brake resistor short circuit to its enclosure or internal winding short, causing an overload on the DC bus during braking.

Click steps to track your progress.

1. 1

   Disconnect motor power cables (U, V, W) from the drive output terminals (T1, T2, T3). Measure resistance between each phase and to ground (motor frame) using a multimeter (expect >1M Ohm).

2. 2

   Inspect the entire length of the motor power cable for physical damage, insulation breakdown, or signs of overheating. Replace cable if insulation resistance (measured with a megohmmeter at 1000VDC) is below 5MOhm.

3. 3

   With motor disconnected, power on the drive. If the fault persists, verify all control wiring connected to drive I/O terminals (e.g., X1-1 to X1-10) for shorts to ground or other signals.

4. 4

   If an external brake resistor is used, disconnect its connections to the drive. Measure the resistor's value with an ohmmeter and compare it to the specified value (e.g., 20 Ohms for a 5kW drive).

5. 5

   If the fault persists with all external connections (motor, brake resistor, control I/O) removed, the drive's internal power stage components (e.g., IGBTs) are likely damaged, requiring drive replacement or factory service.