Troubleshooting - SPX Marley NC Series Installation Operation & Maintenance

troubleshooting

Trouble Cause
Power not available at motor
terminals
Wrong connections
Motor will not start
Low voltage
Open circuit in motor winding
Fan drive stuck
Rotor defective
Motor running single-phase
Motor leads connected incorrectly
Bad bearings
Unusual motor noise
Electrical unbalance
Air gap not uniform
Rotor unbalance
Cooling fan hitting end bell-guard
Wrong voltage or unbalanced
voltage
Overload
Wrong motor RPM
Bearings over greased
Wrong lubrication in bearings
One phase open
Motor runs hot
Poor ventilation
Winding fault
Bent motor shaft
Insufficient grease
Too frequent starting or speed
changes
Deterioration of grease or foreign
material in grease
Bearings damaged
Voltage too low at motor terminals
because of line drop
Motor does not come
up to speed
Broken rotor bars
Wrong motor rotation Wrong sequence of phases
30
Remedy
Check power at starter. Correct any bad connections between the
control apparatus and the motor.
Check starter contacts and control circuit. Reset overloads, close
contacts, reset tripped switches or replace failed control switches.
If power is not on all leads at starter, make sure overload and short
circuit devices are in proper condition.
Check motor and control connections against wiring diagrams.
Check nameplate voltage against power supply. Check voltage at motor
terminals.
Check stator windings for open circuits.
Disconnect motor from load and check motor and Geareducer for
cause of problem.
Look for broken bars or rings.
Stop motor and attempt to start it. Motor will not start if single phased.
Check wiring, controls and motor.
Check motor connections against wiring diagram on motor.
Check lubrication. Replace bad bearings.
Check voltages and currents of all three lines. Correct if required.
Check and correct bracket fits or bearing.
Rebalance.
Reinstall for replace fan
Check voltage and current of all three lines against nameplate values.
Check fan blade pitch. See Fan User Manual. Check for drag in fan
drivetrain as from damaged bearings.
Check nameplate against power supply. Check RPM of motor and gear
ratio.
Remove grease reliefs. Run motor up to speed to purge excessive
grease.
Change to proper lubricant. See motor manufacturer's instructions.
Stop motor and attempt to start it. Motor will not start if single phased.
Check wiring controls and motor
Clean motor and check ventilation openings. Allow ample ventilation
around motor.
Check with Ohmmeter.
Straighten or replace shaft.
Remove plugs and regrease bearings.
Limit cumulative acceleration time to a total of 30 seconds per hour.
Set on/off or speed change set-points farther apart. Consider installing
a Marley VFD for fine temperature control.
Flush bearings and relubricate.
Replace bearings.
Check transformer and setting of taps. Use higher voltage on
transformer terminals or reduce loads. Increase wire size or reduce
inertia.
Look for cracks near the rings. A new rotor may be required. Have
motor service person check motor.
Switch any two of the three motor leads.