Rockwell Automation MV SMC Flex Motor Controller (for Series K or later) - Manual (Page 128)

118 Rockwell Automation Publication 1560E-UM051F-EN-P - June 2013
Chapter 9 Troubleshooting
Table 23 - Miscellaneous Situations
(1)
Display Possible Causes Possible Solutions
Motor current and voltage fluctuates with steady load • Motor
• Erratic Load • Verity type of motor as a standard squirrel cage induction
motor
• Check load conditions
Erratic operation • Loose connections • Shut off all power to controller and check for loose connections
Accelerates too fast • Starting time
• Initial torque
• Current limit setting
• Kickstart • Increase starting time
• Lower initial torque setting
• Decrease current limit setting
• Lower kickstart time or turn off
Accelerates too slow • Starting time
• Initial torque
• Current limit setting
• Kickstart • Decrease starting time
• Increase initial torque setting
• Increase current limit setting
• Increase kickstart time or turn off
Fan does not operate • Wiring
• Failed fans(s) • Check wiring and correct if necessary
• Replace fan(s)
Motor stops too quickly with Soft Stop option • Time setting • Verify the programmed stopping time and correct if necessary
Motor stops too slowly with Soft Stop option • Stopping time setting
• Misapplication • Verify the programmed stopping time and correct if necessary
• The Soft Stop option is intended to extend the stopping time
for loads that stop suddenly when power is removed from the
motor.
Fluid surges with pumps still occur with the Soft Stop option • Misapplication • Soft Stop ramps voltage down over a set period of time. In the
case of pumps, the voltage may drop too rapidly to prevent
surges. A closed loop system such as Pump Control would be
more appropriately suited.
• Refer to Publication 150-911
Motor overheats • Overload
• Blocked ventilation
• Duty cycle
• Allow motor to cool and reduce load.
• Remove blockage and ensure motor is being adequately
cooled.
• Preset Slow Speed and Accu-Stop options: Extended operation
at slow speeds reduces motor cooling efficiency. Consult motor
manufacturer for motor limitations.
• Smart Motor Braking option: Check duty cycle. Consult motor
manufacturer for motor limitations.
Motor short circuit • Winding fault • Identify fault and correct
• Check for shorted SCR; replace if necessary
• Ensure power terminals are secure
Motor coasts when option stop is programmed • Option not programmed
• Current loop power supply not active
• Incorrect control logic • Verify the option parameter settings and correct if necessary
• Verify current loop power supply (refer to
Power Supply Tests
on page 64 of Chapter 3 )
• Verify connections to module terminals 16 and 17 (refer
to Functional Description on page 25 of Chapter 1 )
(1) Various faults may occur if Parameter #15 is set to “Delta”. It must be set to “Line” for all MV applications.
TIP For Pump Stop issues, refer to Pump Application Considerations on page 20 of
Chapter 1 .