Magnetek IMPULSE VG+ Series 3, Instruction Manual, Page: 165 / 183

IMPULSE•VG+ Series 3 Instruction Manual – 07/25/05
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6. Increase the value of C8-13.
Fault Code: OC–Over Current Fault
Definition
An over current fault is caused if the output current exceeds 200% of the inverter rated output
current. This fault can be caused by short circuits in the wiring or in the motor, and it can also be
caused by parameters that are not adjusted properly. One other cause of this alarm could be erratic or
no encoder feedback. In the last instance, the drive is trying to command the motor to hold a position
but due to the encoder problem, is unable to find the correct position. This would cause the drive to
increase current output to the motor in an attempt to correct the position until an over current fault
occurs.
Corrective Action
1. Check the motor wiring and the motor itself for a short between phases.
2. Check the alignment of the encoder pulse wheel with the sensor head, or the encoder shaft
coupling (depending on the type of encoder used). If the pulse wheel is misaligned or the shaft
coupling is loose the drive will get erratic pulse signals or no signals at all possibly causing an
OC fault. Repairs to the encoder wheel or shaft coupling should be made immediately before
again attempting to operate the hoist.
3. If the encoder appears to have no mechanical problems, the encoder cable should be checked for
damage and replaced if a problem is found.
3.1 Each of the encoder wires should be check for continuity.
3.2 The wires should be checked for shorts between any two wires.
3.3 The shield should be check for proper grounding.
3.4 The wires should be checked for shorts to the shield or ground.
3.5 Visually inspect the cable for damage that may be causing intermittent problems.
4. If none of the above steps has identified a valid problem(s), check if any of the torque limit
parameters (C7-01 to C7-04) have been changed. If these parameters have been changed to
allow a higher torque value, it could cause over current trips.
NOTE: Changing these parameters could also induce speed deviation or overload faults.
Only a trained technician should modify these parameters. It is desirable to have as
fast a fault reaction time as possible without causing nuisance trips.