Speed Deviation

What does dEv mean?

This fault occurs when the difference between the motor's detected speed and its commanded speed exceeds a set detection level (F1-10) for a specified duration (F1-11). Common causes include excessive load, improperly short acceleration/deceleration times, a mechanically locked-up load, or an engaged holding brake. This indicates the motor is not achieving its commanded speed, potentially leading to process delays or equipment damage if the load is stalled.

• Mechanical binding or obstruction in the load, increasing torque demand beyond motor capability.
• Incorrect encoder feedback wiring or damaged encoder causing inaccurate speed signal to drive.
• Motor undersized for the application load, leading to excessive slip at commanded speed.
• Drive PID loop tuning parameters (e.g., F2-xx) are unstable or too aggressive for the mechanical system.
• Insufficient motor torque at low speeds due to poor flux vector control tuning or motor parameter mismatch (e.g., P1-03 for motor rated current).

Click steps to track your progress.

1. 1

   1. Confirm mechanical load is free from binding; manually rotate the shaft to check for resistance.

2. 2

   2. Verify encoder feedback wiring (e.g., A/B/Z signals) at drive terminals (e.g., TB2:1-6) using an oscilloscope to check signal integrity.

3. 3

   3. Check parameter F1-10 (Speed Deviation Detection Level) and F1-11 (Speed Deviation Detection Time) and adjust if current settings are too tight for the application.

4. 4

   4. Perform an autotune (e.g., P3-01 = 2) of the motor with the load disconnected if safe, to optimize motor control parameters.

5. 5

   5. Monitor the actual motor speed feedback (e.g., via display parameter U1-01) and the commanded speed reference (e.g., U1-03) simultaneously to observe the deviation.

6. 6

   6. Measure the motor output current (e.g., U1-06) during operation to identify potential overload conditions.