Power unit: Braking chopper overcurrent

What does F30055 mean?

An excessive current has been detected flowing through the braking chopper circuit. This is typically caused by a short circuit within the braking resistor itself or if the external braking resistor is undersized for the application's regenerative energy requirements. An overcurrent condition can quickly damage the braking chopper or connected components.

• A short circuit within the external braking resistor itself or between its terminals (X1, X2, X3).
• Braking resistor cabling insulation breakdown, causing a phase-to-ground or phase-to-phase short.
• The external braking resistor resistance (P0250) is set too low or the physical resistor is undersized for the application, leading to excessive current.
• Internal fault within the braking chopper IGBT or its gate drive circuitry inside the power unit.
• Incorrect parametrization of the supply voltage (P0210) leading to an incorrect DC link voltage (r0026) and chopper operation.

Click steps to track your progress.

1. 1

   Power off the drive and lock out. Disconnect all braking resistor cables from the drive's output terminals (e.g., X1, X2, X3).

2. 2

   Measure the resistance of the external braking resistor(s) with an ohmmeter; compare the measured value to parameter P0250.

3. 3

   Inspect the braking resistor cables for physical damage, chafing, or signs of insulation breakdown; check continuity and insulation resistance.

4. 4

   With the braking resistors disconnected, power on the drive. If fault F30055 clears, the issue lies in the external resistor circuit.

5. 5

   Verify that parameter P0210 (supply voltage) is correctly configured to the actual measured AC input voltage.

6. 6

   Confirm that parameter P0250 (braking resistor nominal resistance) matches the actual resistance of the connected braking resistor.