Rockwell Automation Publication 20A-UM001N-EN-P - July 2013 87
Troubleshooting Chapter 2
Table 9 - Motor and/or Drive Does Not Accelerate to Commanded Speed
Table 10 - Motor Operation is Unstable
Table 11 - Drive Does Not Reverse Motor Direction
Table 12 - Stopping the Drive Results in a Decel Inhibit Fault
Causes Indication Corrective Action
Acceleration time is excessive. None Reprogram [Accel Time x] (see page 41
).
Excess load or short acceleration times force the
drive into current limit, slowing or stopping
acceleration.
None Check [Drive Status 2], bit 10 to see if the drive is in
Current Limit (see page 52
).
Remove excess load or reprogram [Accel Time x]
(see page 41
).
Speed command source or value is not as expected. None Check for the proper Speed Command by using the
steps in Table 8 on page 86
.
Programming is preventing the drive output from
exceeding limiting values.
None Check [Maximum Speed] page 31
and
[Maximum Freq] page 25 to assure that speed is
not limited by programming.
Cause Indication Corrective Action
Motor data was incorrectly entered or Autotune
was not performed.
None 1. Correctly enter motor nameplate data.
2. Perform “Static” or “Rotate” procedures in the
Autotune parameter (see page 27
).
Causes Indication Corrective Action
Digital input is not selected for reversing control. None Check [Digital Inx Sel] (see page 68
). Choose
correct input and program for reversing mode.
Digital input is incorrectly wired. None Check input wiring. Refer to PowerFlex 70
Adjustable Frequency AC Drive Installation
Instructions, publication 20A-IN009.
Direction mode parameter is incorrectly
programmed.
None Reprogram the analog “Bipolar” or digital
“Unipolar” control in the [Direction Mode]
parameter (see page 49).
Motor wiring is improperly phased for reverse. None Switch two motor leads.
A bipolar analog speed command input is
incorrectly wired or signal is absent.
None 1. Use meter to check that an analog input voltage
is present.
2. Check wiring. Refer to PowerFlex 70 Adjustable
Frequency AC Drive Installation Instructions,
publication 20A-IN009.
Positive voltage commands forward direction.
Negative voltage commands reverse direction.
Causes Indication Corrective Action
The bus regulation feature is enabled and is halting
deceleration due to excessive bus voltage. Excess
bus voltage is normally due to excessive
regenerated energy or unstable AC line input
voltages.
Internal timer has halted drive operation.
Decel Inhibit
fault screen.
LCD Status Line
indicates
“Faulted”.
1. See Attention statement on page 10
.
2. Reprogram bus regulation (parameters 161 and
162) to eliminate any “Adjust Freq” selection.
3. Disable bus regulation (parameters 161 and
162) and add a dynamic brake.
4. Correct AC input line instability or add an
isolation transformer.
5. Reset drive.
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