PI Feedback Loss Alarm

What does PIFB-AL mean?

This alarm occurs when the PI function's feedback signal is determined to be lost, as configured by parameter b5-12 set to '1: Alarm'. The drive acknowledges the loss of feedback but continues to operate without stopping, and it does not energize the fault output (MA-MB), indicating a degraded control state rather than a critical shutdown.

• Break in the wiring of the analog feedback signal (e.g., 4-20mA, 0-10V) to the drive's analog input terminal.
• Faulty or disconnected sensor providing the PI feedback (e.g., pressure transducer, flow meter, level sensor).
• Incorrect scaling or type selection for the analog input parameter (e.g., H3-02, H3-06, H3-09) for the feedback signal.
• Loss of auxiliary power to the feedback sensor itself, resulting in zero output.
• The process variable falling outside the expected operating range, causing the sensor output to drop below the detection threshold.

Click steps to track your progress.

1. 1

   1. Verify the feedback sensor is powered ON and functioning correctly, measuring its output signal (e.g., current or voltage) directly at its terminals.

2. 2

   2. Using a multimeter, check continuity of the feedback signal wiring from the sensor to the drive's analog input terminal (e.g., A1, A2).

3. 3

   3. Confirm drive parameters for the analog input (e.g., H3-02, H3-06, H3-09 type and scaling) match the sensor output specifications.

4. 4

   4. Inject a known test signal (e.g., 4mA or 0V) into the drive's analog input terminals to verify the drive's reading accuracy.

5. 5

   5. Check parameter b5-12 (PI Feedback Loss Detection) setting to ensure it is configured for '1: Alarm' and review the detection threshold.