IMPULSE•G+/VG+ Series 4 Technical Manual
November 2022
Page 206
6.2.3 BE1–Rollback Fault
Definition
A BE1 fault indicates that the VFD has released the brake, but has not started to accelerate the motor when it
detects more than the expected encoder feedback. A BE1 fault will occur if the pulses received during the BE1
detection time (C08-04) are greater than the expected number of pulses (C08-05). This is typically caused by the
VFD/motor having insufficient torque to accelerate the load.
Correction Action
1. Check the encoder cable for damage and proper grounding. Replace it if a problem is found.
•
Each of the encoder signals should be checked for excessive noise.
•
The shielded encoder cable should be properly grounded.
•
Visually inspect the cable for damage that may be causing intermittent problems.
2. Check the alignment of the encoder pulse wheel and sensor head, or the encoder shaft coupling. If the pulse
wheel is misaligned or the shaft coupling is loose the VFD may get erratic pulse signals and cause a BE1 fault.
Make repairs before attempting to operate the hoist.
3. If none of the steps identified a problem(s), only then should the BE1 detection parameters be adjusted.
NOTE:
It is desirable to have as fast a fault reaction time as possible without causing nuisance faults.
4. The Rollback Pulse Count (C08-05) setting should remain as close to 800 pulses as possible.
6.2.4 BE2–Torque Proving Fault
Definition
A BE2 fault indicates that the VFD was unable to develop sufficient torque before releasing the brake. A BE2 fault
occurs when the torque (U01-09) is less than the Initial Forward Brake Release
Torque (C08-16) during the current
feedback timer (C08-02) at start. This typically indicates that the brake is slipping while torque is building up in the
motor before releasing the brake.
NOTE:
This fault typically indicates a failed brake. Power should NOT be removed while this alarm is active and
the load should be moved to a safe location and lowered before proceeding with any corrective action.
Corrective Action
1. Check the brake for proper operation and adjustment. If the brake does not set, is improperly adjusted or is
excessively worn, it may not be able to hold the load. This can cause encoder pulses to be received while
torque is building up in the motor.
2. Check the encoder cable for damage and proper grounding. Replace it if a problem is found.
•
Each of the encoder signals should be checked for excessive noise.
•
The shielded encoder cable should be properly grounded.
•
Visually inspect the cable for damage that may be causing intermittent problems.
3. Check the alignment of the encoder pulse wheel and sensor head, or the encoder shaft coupling. If the pulse
wheel is misaligned or the shaft coupling is loose the VFD may get erratic pulse signals and cause a BE2 fault.
Make repairs before attempting to operate the hoist.
4. Perform a Brake Torque test to verify the torque matches brake specifications.
5. If none of the above steps has identified a valid problem(s), the brake may need to be replaced.
NOTE:
The Current Feedback Timer (C08-02) should be set as low as possible without causing nuisance faults.
