Applicable Systems
CPX-FVDA-P
Symptoms
The Festo CPX terminal reports fault code 5 indicating undervoltage in the power supply (UVAL). The load power supply voltage UVAL has dropped below 20V DC (with a 24V nominal system). All output channels will be passivated (safety切断) as the module cannot guarantee safe operation at reduced voltage.
Possible Causes
- Power supply failure or voltage drop below 20V DC threshold
- Overloaded power supply causing voltage sag under load
- Power supply wiring resistance too high causing voltage drop
- Blown fuse or tripped breaker in the power supply circuit
Troubleshooting Steps
- Step 1: Check CPX diagnostic display or LED for fault code 5
Fault code 5 displayed, UVAL voltage reading below 20V - Step 2: Measure actual UVAL voltage at the CPX terminal power input terminals
Voltage reading confirms undervoltage condition - Step 3: Inspect power supply wiring for loose connections, damage, or excessive length
Wiring in good condition, connections tight - Step 4: Verify power supply capacity matches total CPX terminal load current
Power supply rated current exceeds total load current with margin
How to Reset
To reset: 1) Eliminate the undervoltage condition. 2) Perform acknowledgment and recomposition of the module via PROFIsafe. 3) Verify all channels return to normal operation. Caution: All channels are passivated during this fault for safety reasons.
Frequently Asked Questions
- Q: What is the undervoltage threshold for CPX-FVDA-P?
Undervoltage is detected when UVAL drops below 20V DC (nominal 24V system) for more than 200ms. Overvoltage is detected above 29.5V DC for more than 200ms.
- Q: Why are all channels passivated during undervoltage?
At reduced voltage, the output switches may not reliably control the connected loads (valves, actuators). For safety, all outputs are switched to the safe state (off) until voltage is restored.
Source: Festo CPX-FVDA-P System Manual, Document P.BE-CPX-SYS-F-ZH zh 1011NH (festo.com)
Category: Hydraulic & Pneumatic