Capacitor precharge fault

What does CrF mean?

A fault related to the capacitor precharge circuit, either due to a control issue with the precharge relay or a damaged precharge resistor. This fault prevents the drive from powering up correctly, indicating a critical internal hardware failure.

• Failure of the precharge relay (K1) to close or open correctly during power-up sequence.
• Damaged or open-circuit precharge resistor (R_PC) preventing DC bus charging.
• Control circuit malfunction preventing activation of the precharge relay coil.
• Short circuit in the DC bus capacitance (rare but can prevent proper precharge).

Click steps to track your progress.

1. 1

   1. Disconnect input power (L1, L2, L3) and measure the resistance of the precharge resistor (R_PC) within the drive.

2. 2

   2. Verify the voltage supplied to the precharge relay coil (e.g., 24VDC) during the power-up sequence.

3. 3

   3. Visually inspect the precharge relay contacts for signs of pitting, burning, or welding.

4. 4

   4. Measure the DC bus voltage across the positive and negative terminals after power-up attempt to confirm precharge sequence failure.

5. 5

   5. If accessible, inspect main capacitors for signs of bulging or leakage, indicating internal damage.