Rockwell Automation MV SMC Flex Motor Controller (for Series K or later) - Manual (Page 127)

Rockwell Automation Publication 1560E-UM051F-EN-P - June 2013 117
Troubleshooting Chapter 9
Table 19 - Motor Will Not Start – No Output Voltage to the Motor
Table 20 - Motor Rotates (but does not accelerate to full speed)
Table 21 - Motor Stops While Running
Table 22 - Irregular Starts
Display Possible Causes Possible Solutions
Fault displayed • See fault description • See Table 18 addressing fault conditions
Display is blank • Control voltage is absent
• Failed control module • Check control wiring and correct if necessary
• Replace control module
Stopped 0.0 Amps • Pilot devices
• SMC Enable input is open at terminal 13
• Terminal 16 is open
• Start-Stop control has not been enabled for the human
interface module
• Control voltage
• Failed control module
• Check wiring
• Check wiring
• Check wiring
• Follow the instructions on
page 104 to page 106 to
enable control capability
• Check control voltage
• Replace control module
Starting • Two or three power phases are missing • Check power system
• Check voltage sensing module and connections
Display Possible Causes Possible Solutions
Fault displayed • See fault description • See Table 18 addressing fault conditions
Starting • Mechanical problems
• Inadequate Current Limit setting
• Failed control module
• Check for binding or external loading and correct
• Check motor
• Adjust the Current Limit Level to a higher setting
• Replace control module
Display Possible Causes Possible Solutions
Fault displayed • See fault description • See Table 18 addressing fault conditions
Display is blank • Control voltage is absent
• Failed control module • Check control wiring and correct if necessary
• Replace control module
Stopped 0.0 Amps • Pilot devices
• Failed control module • Check control wiring and correct if necessary
• Replace control module
Starting • Two or three power phases are missing
• Failed control module • Check power system
• Check voltage sensing module and connections
• Replace control module
Symptom Possible Causes Possible Solutions
Bypass contactor closes before motor is up to speed • Ramp time too short
• Motor characteristics cause Up-to-Speed sensing too
early
• Increase ramp time (parameter 18)
• Adjust parameter 114 higher (no more than 5% at a
time)
Motor is up to speed but bypass contactor is delayed in
closing or does not close at all • Ramp time too long
• Motor characteristics cause Up-to-Speed sensing too
late or not at all
• Decrease ramp time
• Adjust parameter 114 lower (no more than 5% at a
time)
Rough start, erratic current, growling from the motor
(may see Line Faults) • Poor grounding of the power system or controller
• Poor power quality, electrical noise, harmonics, VFD line
notching
• Resolve ground issues
• Adjust parameter 117 higher. Typical settings are 35 or
40. Not recommended to exceed 75 or go below 25.
During a Pump Stop, the motor takes more than 5 seconds
to begin to decelerate or takes longer than the
programmed stop time • Motor or pump characteristics do not match the default
setting
• Adjust parameter 34 to between 20 and 30 (not
recommended to go above 40).
TIP Although the default settings accommodate the vast majority of applications,
these tuning parameters may require more than one adjustment to achieve
optimal results. Some parameters are affected by motor loading and power
system conditions, so one setting may not be optimal for all conditions.