24V supply low

What does 47 mean?

The 24V DC supply generated by the switch-mode power supply (SMPS) on the power card is operating below its acceptable voltage range. This low voltage can cause erratic behavior or non-operation of components that rely on the 24V supply, potentially leading to incorrect sensor readings or control issues.

• Overload on the 24VDC internal supply due to too many connected external devices or modules.
• Partial failure or degradation of the switch-mode power supply (SMPS) component responsible for the 24VDC rail.
• Short circuit or excessive current draw on one of the circuits powered by the internal 24VDC supply (e.g., control board, I/O modules).
• Component failure (e.g., filtering capacitor, regulator) specific to the 24VDC section of the power card.
• Loose connection or high resistance in the 24VDC distribution path within the drive.

Click steps to track your progress.

1. 1

   Disconnect main power supply to the frequency converter at the upstream breaker. Verify zero voltage.

2. 2

   Visually inspect the power card for any signs of burnt components, particularly around the 24VDC regulation section.

3. 3

   With power applied, measure the actual 24VDC supply voltage at accessible test points or terminals (e.g., terminal 12).

4. 4

   Systematically disconnect external devices or modules (e.g., fieldbus cards, expansion I/O) powered by the internal 24VDC supply one by one to identify an overload.

5. 5

   Check for any short circuits on the 24VDC output terminals or internal wiring by measuring resistance to ground.

6. 6

   If the voltage remains low with no identified external load or short, the power card may need replacement.