| Problem:
Motor fails to start upon initial installation. |
| Likely
Causes: |
What
to Do: |
| Motor
is miswired. |
Verify
motor is wired correctly. |
| Motor
damaged and rotor is striking stator. |
May
be able to reassemble; otherwise, motor should be replaced. |
| Fan
guard bent and contacting fan. |
Replace
fan guard. |
| Problem:
Motor has been running, then fails to start. |
| Likely
Causes: |
What
to Do: |
| Fuse
or circuit breaker tripped. |
Replace
fuse or reset the breaker. |
| Stator
is shorted or went to ground. Motor will make a humming noise
and the circuit breaker or fuse will trip. |
Disassemble
motor and inspect windings and internal connections. A blown
stator will show a burn mark. Motor must be replaced or the
stator rewound. |
| Motor
overloaded or load jammed. |
Inspect
to see that the load is free. Verify amp draw of motor versus
nameplate rating. |
| Capacitor
(on single phase motor) may have failed. |
First
discharge capacitor. To check capacitor, set volt-ohm meter
to RX 100 scale and touch its probes to capacitor terminals.
If capacitor is OK, needle will jump to zero ohms, and drift
back to high. Steady zero ohms indicates a short circuit; steady
high ohms indicates an open circuit. |
| Starting
switch has failed. |
Disassemble
motor and inspect both the centrifugal and stationary switches.
The weights of the centrifugal switch should move in and out
freely. Make sure that the switch is not loose on the shaft.
Inspect contacts and connections on the stationary switch. Replace
switch if the contacts are burned or pitted. |
| Problem:
Motor runs but dies down. |
| Likely
Causes: |
What
to Do: |
| Voltage
drop. |
If
voltage is less than 10% of the motor's rating contact power
company or check if some other equipment is taking power away
from the motor. |
| Load
increased. |
Verify
the load has not changed. Verify equipment has not gotten tighter.
If fan application, verify the air flow has not changed. |
| Problem:
Motor takes too long to accelerate. |
| Likely
Causes: |
What
to Do: |
| Defective
capacitor. |
Test
capacitor per previous instructions. |
| Faulty
stationary switch. |
Inspect
switch contacts and connections. Verify that switch reeds have
some spring in them. |
| Bad
bearings. |
Noisy
or rough feeling bearings should be replaced. |
| Voltage
too low. |
Make
sure that the voltage is within 10% of the motor's nameplate
rating. If not, contact power company or check if some other
equipment is taking power away from the motor. |
| Problem:
Motor runs in the wrong direction. |
| Likely
Causes: |
What
to Do: |
| Incorrect
wiring. |
Rewire
motor according to wiring schematic provided. |
| Problem:
Motor overload protector continually trips. |
| Likely
Causes: |
What
to Do: |
| Load
too high. |
Verify
that the load is not jammed. If motor is a replacement, verify
that the rating is the same as the old motor. If previous motor
was a special design, a stock motor may not be able to duplicate
the performance. Remove the load from the motor and inspect
the amp draw of the motor unloaded. It should be less than the
full load rating stamped on the nameplate. |
| Ambient
temperature too high. |
Verify
that the motor is getting enough air for proper cooling. Most
motors are designed to run in an ambient temperature of less
than 40°C. (Note: A properly operating motor may be hot to the
touch.) |
| Protector
may be defective. |
Replace
the motor's protector with a new one of the same rating. |
| Winding
shorted or grounded. |
Inspect
stator for defects, or loose or cut wires that may cause it
to go to ground. |
| Problem:
Motor vibrates. |
| Likely
Causes: |
What
to Do: |
| Motor
misaligned to load. |
Realign
load. |
| Load
out of balance. (Direct drive application.) |
Remove
motor from load and inspect motor by itself. Verify that motor
shaft is not bent. Rule of thumb is .001" runout per every inch
of shaft length. |
| Motor
bearings defective. |
Test
motor by itself. If bearings are bad, you will hear noise or
feel roughness. Replace bearings. Add oil if a sleeve of bearing.
Add grease if bearings have grease fittings. |
| Rotor
out of balance. |
Inspect
motor by itself with no load attached. If it feels rough and
vibrates but the bearings are good, it may be that the rotor
was improperly balanced at the factory. Rotor must be replaced
or rebalanced. |
| Motor
may have too much endplay. |
With
the motor disconnected from power turned shaft. It should move
but with some resistance. If the shaft moves in and out too
freely, this may indicate a preload problem and the bearings
may need additional shimming. |
| Winding
may be defective. |
Test
winding for shorted or open circuits. The amps may also be high.
Replace motor or have stator rewound. |
| Problem:
Bearings continuously fail. |
| Likely
Causes: |
What
to Do: |
| Load
to motor may be excessive or unbalanced. |
Besides
checking load, also inspect drive belt tension to ensure it's
not too tight may be too high. An unbalanced load will also
cause the bearings to fail. |
| High
ambient temperature. |
If
the motor is used in a high ambient, a different type of bearing
grease may be required. You may need to consult the factory
or a bearing distributor. |
| Problem:
The motor, at start up, makes aloud rubbing or grinding noise. |
| Likely
Causes: |
What
to Do: |
| Rotor
may be striking stator. |
Ensure
that motor was not damaged in shipment. Frame damage may not
be repairable. If you cannot see physical damage, inspect the
motor's rotor and stator for strike marks. If signs of rubbing
are present, the motor should be replaced. Sometimes simply
disassembling and reassembling motor eliminates rubbing. Endbells
are also sometimes knocked out of alignment during transportation. |
| Problem:
Start capacitors continuously fail. |
| Likely
Causes: |
What
to Do: |
| The
motor is not coming up to speed quickly enough. |
Motor
may not be sized properly. Verify how long the motor takes to
come up to speed. Most single phase capacitor start motors should
come up to speed within three seconds. Otherwise the capacitors
may fail. |
| The
motor is being cycled too frequently. |
Verify
duty cycle. Capacitor manufacturers recommend no more than 20,
three-second starts per hour. Install capacitor with higher
voltage rating, or add bleed resistor to the capacitor. |
| Voltage
to motor is too low. |
Verify
that voltage to the motor is within 10% of the nameplate value.
If the motor is rated 208-230V, the deviation must be calculated
from 230V. |
| Starting
switch may be defective, preventing the motor from coming out
of start winding. |
Replace
switch. |
| Problem:
Run capacitor fail. |
| Likely
Causes: |
What
to Do: |
| Ambient
temperature too high. |
Verify
that ambient does not exceed motor's nameplate value. |
| Possible
power surge to motor, caused by lightning strike or other high
transient voltage. |
If
a common problem, install surge protector. |
