Controller Power Supply Undervoltage

What does Controller Undervoltage mean?

The internal power supply providing voltage to the drive's control circuits is operating below its nominal level. This is an internal hardware fault that can prevent the drive's logic and control functions from operating correctly, potentially leading to system instability or failure to start.

• Internal power supply unit (PSU) failure within the drive, responsible for generating 24VDC or 5VDC for control electronics.
• Short circuit on one of the drive's internal control boards or an external control circuit connected to the drive's 24VDC supply (e.g., terminal +24V).
• Component degradation (e.g., electrolytic capacitors) in the control power supply section of the drive.
• Overload on the auxiliary 24VDC output of the drive (if used to power external devices), drawing excessive current.
• Damage to control board traces or components due to ESD (Electrostatic Discharge) or voltage spikes.

Click steps to track your progress.

1. 1

   1. Power down the drive completely (wait for DC bus discharge). Disconnect all external control wiring connected to the drive's 24VDC auxiliary supply output (e.g., +24V terminal).

2. 2

   2. Power up the drive and check if the fault clears. If it does, an external short or overload on the auxiliary supply is likely the cause.

3. 3

   3. If accessible, measure the internal control supply voltages (e.g., 24VDC, 5VDC) at designated test points on the control board, comparing them to specified values in the drive's service manual.

4. 4

   4. Visually inspect the control board for swollen capacitors, burn marks, or damaged ICs (Integrated Circuits) that would indicate an internal power supply issue.

5. 5

   5. Reduce any external load connected to the drive's auxiliary 24VDC supply if it exceeds the drive's rated output current (e.g., 100mA).

6. 6

   6. If the fault persists after external checks and with good incoming power, the internal control power supply is faulty, requiring drive repair or replacement.