Rockwell Automation 8720MC Drives Integration Manual - Manual (Page 58)

Publication 8720MC-IN002A-EN-P — December 2002
3-4 Troubleshooting Your 8720MC Servo Drive
Fault Descriptions When a fault occurs, the fault is displayed until you initiate a Drive
Error Reset from the digital I/O or depress the stop button from the
HIM module or by executing MSFR from RSLogix 5000 if used with
SERCOS.
The following table provides a list of the faults, their probable causes
and the drives response to the faults.
Fault Message RSLogix
(HIM)
Probable Cause/Drive Response Corrective Actions
No Fault Message
(condition indicated by
on-screen message)
(Axis 1 ATune Flt)
Auto Tuning procedure failed to complete
successfully Assure that the drive and motor are functional and
repeat the auto tune procedure.
DriveOvervoltageFault
(Bus Overvoltage)
Bus voltage exceeded 810V dc. This is
usually caused by a high inertia motor load
being decelerated very fast.
/ Disable stop: the drive will disable and the
motor will coast to a stop with an error
message on the HIM. The control board
status LED will be flashing and the drive OK
output will be open.
• Monitor the AC line for high voltage or transient
conditions.
• Decrease the deceleration parameter for the active
parameter set, param. 137 for set zero
• Decrease the stopping torque, parameter 571.
• Increase the dynamic braking capacity by increasing
the brake chopper capacity.
• Adjust parameter 563 to a lower value. This will
limit the motor deceleration rate.
• Check for 8720MC-RPS faults.
• Reduce the 8720MC-RPS bus voltage
BusUndervoltageFault
(Bus Loss)
The DC bus voltaged has dropped below the
minimum acceptable level.
/ Disable stop
• Monitor the AC line for low voltage or power
interruption.
• Check for 8720MC-RPS faults.
GroundShortFault
(Ground Short)
A current path to earth ground in excess of
drive rated current has been detected at one
of the output terminals. / Disable stop
• Check the motor wiring to the drive output terminals
for a grounded condition.
• Replace the drive
BusUndervoltageFault
(Bus Regulator)
The regenerative power supply has faulted.
/ Disable stop
Investigate the 8720MC-RPS message display on the
unit. Refer to publication 8720MC-RM001 for
diagnostic trouble shooting procedures. Check input 10,
Regen PS-OK.
BusUndervoltageFault
(Bus Precharge)
The precharge time could not complete
within 30 seconds.
DriveOvercurrentFault
(A1: Desat)
There was to much current in the system.
/ Disable stop
Check for shorted motor or motor wiring
PositionErrorFault
(A1: Follow Error)
Excessive following error has been detected.
This means that the motor cannot keep up
with the position command.
/ Regen stop
• Investigate motor load for any possible binding.
• Increase position loop proportional gain
• Increase the allowable following error, parameter
159
DriveOvercurrentFault
(A1: Overcurrent)
A drive overcurrent has occurred. The current
has exceeded 150% of the inverter rated
continuous current.
/ Disable stop.
• Decrease the deceleration parameter for the active
parameter set, param. 137 for set zero. The drive is
particularly sensitive to this fault at high speeds.
• Adjust parameter 563 to a lower value.
• Check for a shorted motor or shorted motor wiring.
• Replace the drive