APS Under Voltage

What does F41 mean?

This is an Escalating Automatic Fault that occurs when the auxiliary power supply experiences an under-voltage shutdown. If this condition triggers 3 times within 30 seconds, it becomes a manual fault, indicating persistent power issues for control circuitry.

• Overload on the auxiliary power supply output (e.g., excessive current drawn by external sensors, contactors, or control circuits).
• Faulty auxiliary power supply (APS) module itself, resulting in reduced output voltage.
• Input voltage to the APS (e.g., 240VAC or 48VDC) is unstable or too low.
• High resistance or partial short circuit on the APS output wiring causing a voltage drop under load.
• Aging or failing capacitors within the APS, leading to poor voltage regulation.

Click steps to track your progress.

1. 1

   Measure the auxiliary power supply output voltage (e.g., 24VDC, 12VDC) at its terminals under varying loads using a multimeter.

2. 2

   Disconnect all loads from the auxiliary power supply and measure its open-circuit voltage to determine if the APS itself is faulty.

3. 3

   Measure the input voltage to the auxiliary power supply to ensure it meets the specified range (e.g., 240VAC +/- 10% or 48VDC nominal).

4. 4

   Systematically disconnect external devices powered by the APS one by one, while monitoring APS output voltage, to identify an overloaded branch.

5. 5

   Inspect all wiring connected to the auxiliary power supply output for physical damage, loose connections, or signs of overheating that indicate high resistance.