PI Feedback Loss Fault

What does PIFB-FL mean?

This fault occurs when the PI function's feedback signal is determined to be lost, as configured by parameter b5-12 set to '2: Fault'. Upon detection, the drive will coast to a stop and energize the fault output (MA-MB), indicating a critical loss of process control feedback that requires immediate attention.

• Failure of the PI feedback sensor (e.g., pressure transducer, flow meter) connected to the drive's analog input.
• Open circuit or high resistance in the feedback signal wiring between the sensor and drive analog input terminal (e.g., A1, A2, AC).
• Incorrect configuration of PI feedback parameters, such as b5-04 (Feedback Input Selection) or b5-05 (Feedback Gain).
• Feedback signal level consistently below the PI Feedback Loss Detection Level (b5-13) for the set detection time.
• External electromagnetic interference (EMI) or ground loop issues corrupting the low-level analog feedback signal.

Click steps to track your progress.

1. 1

   Measure the analog output signal directly at the feedback sensor terminals to confirm it is producing a valid range (e.g., 4-20mA, 0-10VDC).

2. 2

   Verify continuity and insulation integrity of the feedback signal wiring between the sensor and the drive's analog input terminals (e.g., A1-AC) using a multimeter.

3. 3

   Confirm parameter b5-04 (Feedback Input Selection) matches the connected analog input terminal and b5-12 is set to '2' (Fault).

4. 4

   Adjust parameter b5-13 (PI Feedback Loss Detection Level) to be appropriately low, just above the expected zero signal noise floor.

5. 5

   Apply a known test signal (e.g., from a signal generator) to the drive's analog input terminals to verify the drive correctly processes the feedback.

6. 6

   Inspect for proper shielding and grounding of the feedback signal cable, ensuring it is separated from power cables.