Brake resistor short circuit

What does 25 mean?

This warning is triggered when the brake resistor is detected as short-circuited during operation. While the frequency converter remains operational, its braking function is disabled, posing a safety risk in applications requiring active braking. Continued operation without a functional brake resistor can lead to uncontrolled deceleration or safety hazards.

• Internal short circuit within the brake resistor bank (e.g., element failure, insulation breakdown).
• Short circuit in the wiring between the frequency converter (e.g., terminals 81, 82) and the brake resistor.
• Contamination (e.g., conductive dust, moisture) across the brake resistor terminals.
• Incorrectly rated or specified brake resistor, leading to premature failure under high stress.
• Faulty brake chopper detection circuit on the frequency converter's power board.

Click steps to track your progress.

1. 1

   Disconnect main power supply to the frequency converter at the upstream breaker. Verify zero voltage at L1, L2, L3 terminals.

2. 2

   Disconnect the brake resistor cables from the frequency converter's brake terminals (e.g., 81, 82).

3. 3

   Measure the resistance of the brake resistor directly at its terminals using a multimeter. Compare to specified ohmic value (e.g., 22 Ohms).

4. 4

   Inspect the wiring between the frequency converter and the brake resistor for any signs of insulation damage or shorting.

5. 5

   Check for conductive debris or moisture accumulation on the brake resistor terminals and inside its enclosure.

6. 6

   If the brake resistor resistance is significantly below its specified value (e.g., < 50% of nominal), replace the resistor.