Starting Time Detected Fault (Too Long Start Time)

What does StF mean?

The motor's acceleration period exceeded the maximum allowed starting time ('tLS' parameter). This often indicates that the motor is struggling to accelerate, possibly due to excessive load, an undersized soft starter, or incorrect parameter settings.

• Excessive mechanical load connected to the motor, preventing it from accelerating to full speed within the 'tLS' (start time limit) parameter.
• Motor is undersized for the application, unable to provide sufficient torque to overcome the load inertia.
• Soft starter ramp-up time (ACC parameter) is set too long, exceeding the motor's actual acceleration capability or 'tLS'.
• Insufficient motor starting torque due to low supply voltage or incorrect motor parameters (e.g., motor FLA) in the soft starter setup.
• Mechanical binding or excessive friction in the driven equipment (e.g., seized bearings, misaligned coupling, worn gears).

Click steps to track your progress.

1. 1

   1. Measure the actual motor current during start-up to assess load and compare it to the motor's full load ampere (FLA) rating.

2. 2

   2. Disconnect the motor from the load (if safe and feasible) and test start to determine if the motor accelerates normally without load.

3. 3

   3. Review and adjust the soft starter's ramp-up time (ACC parameter) and starting current limit (CLI parameter) to optimize acceleration.

4. 4

   4. Verify the 'tLS' (maximum starting time) parameter is set appropriately for the application's required acceleration profile.

5. 5

   5. Inspect driven mechanical equipment (e.g., bearings, belts, couplings) for signs of binding or excessive friction.