PID Feedback Loss

What does FBL mean?

This fault occurs when PID Feedback Loss Detection is enabled (b5-12=2) and the PID feedback signal drops below the defined level (b5-13) for a specified time (b5-14). It signifies that the PID feedback source (e.g., transducer, sensor, building automation signal) is either incorrectly installed, malfunctioning, or disconnected. Loss of PID feedback means the Drive cannot maintain accurate process control, potentially causing system instability.

Additional Steps

Steps 1–2 are listed in Priority Fix.

1. 3

   Check the functionality of the PID feedback source itself, ensuring it is providing an accurate and stable signal.

2. 4

   Review the PID Feedback Loss Detection Level (b5-13) and Detection Time (b5-14) settings for appropriateness to the application.