ABB CRB 15000, Product Manual, Page: 1062 / 1096

7.3 Manipulator collapses on power down
Description
The manipulator is able to work correctly while Motors ON is active, but when
Motors OFF is active, one or more axes drops or collapses under its own weight.
The holding brakes (normally one in each motor), is not able to hold the weight of
the manipulator arm.
Consequences
For a heavy robot, the collapse can cause severe injury to personnel working in
the area or severe damage to the robot and/or surrounding equipment.
For a small robot, the collapse can cause injury to personnel working close to the
robot or damage to the robot and/or surrounding equipment.
Possible causes
The symptom can be caused by:
• Faulty brake.
• Faulty power supply to the brake.
Recommended actions
The following actions are recommended:
Information Action
Determine which motor(s) causes the robot
to collapse. 1
See the circuit diagram. Check the brake power supply to the col-
lapsing motor during the Motors OFF state. 2
Check for any recorded fault status.
1062 Product manual - CRB 15000
3HAC077389-001 Revision: L
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7 Troubleshooting
7.3 Manipulator collapses on power down