,
Motor is started too frequently
See section 3.4.5.3
,
Supply voltage too low, too high, or unbalanced
(1) Ensure that steady state supply voltage at motor terminals is within limits (see
section 3.4.1.3) Correct as needed (2) Reconnect motor per input voltage (3)
Obtain correct motor to match power supply.
= 1
,
Motor misaligned to load.
Realign load
7,
Load out of balance (Direct drive application)
(1) Ensure that load is dynamically balanced: (2) Remove motor from load and
inspect motor by itself. Verify that motor shaft is not bent. Rule of thumb is 0.002”
runout for shafts extension lengths up to 3.00”. Add 0.0005” per every additional
inch of shaft length beyond 3.00”.
,
Uneven tension on multiple belts
Mixing new with used belts. Replace multiple belt applications with a complete set
of matched belts.
?,
Driven load operating at resonant point / natural
frequency.
(1) De energize motor and record vibration as load coasts from 100% speed to 0
RPM. If vibration drops immediately, vibration source is electrical. If levels do not
drop immediately, source is mechanical (2) Redesign system to operate below the
resonant point (3) On VFD driven loads, program skip frequencies to bypass
resonant points (4) Increase carrier frequency to obtain <3% THD current (5) On
variable torque loads reduce volts/hertz below base speed.
,
VFD torque pulsations
(1) Adjust VFD to obtain <3% THD current @ rated motor current (2) Adjust VFD
stability for smooth operation. Vector drives may be unstable at light load.
,
Motor miswired at terminal box
Match motor lead wiring to nameplate connection diagram.
6,
Uneven, weak or loose mounting support.
Shim, strengthen or tighten where required.
&,
Motor bearings defective
Test motor by itself. If bearings are bad, you will hear noise or feel roughness.
Roller bearings are normally noisy when operated without load. If sleeve bearing,
add oil per nameplate instructions. For motors with regreasing provisions, add
grease per relubricating instructions (see section 4.2.3).
If noise persists contact
warranty service.
,
Motor out of balance
Disconnect from load. Set motor on rubber pads on solid floor. Secure a ½ height
key in shaft keyway and energize from balanced power supply @ rated voltage.
Record vibration levels and compare with appropriate standards.
If excessive
vibration persists contact motor manufacturer.
7
4
0
,
,
Load to motor may be excessive or unbalanced
(1) If belt drive check system per section 3.3.4.
(2) Other than belting, check
loading on motor shaft. An unbalanced load will also cause the bearings to fail. (3)
Check runouts of mating components, such as a C face and pump flange.
7,
Bearings contaminated.
Motor enclosure not suitable for environment. Replace with correct enclosure
construction
,
Incorrect grease or bearings for ambient extremes.
See section 4.2.1
?,
VFD bearing damage
Ground brush, common mode filter, or insulated bearings must be added. Contact
motor manufacturer.
8
11 4 4
4
:
4
,
,
Contact between rotating and stationary components
Belt squeal during across the line starting is normal: (1) Verify that supply voltage
is within limits (see section 3.4.1.3). (2) Ensure that motor lead wiring matches
nameplate connection diagram: (3) Isolate motor from load. (4) To locate point of
contact turn motor shaft by hand. (5) If point of contact is not located contact
motor service shop.
(
0
,
,
The motor acceleration time is too long
Motor may be too small for load. Record acceleration time. Start capacitors may
fail if acceleration time exceeds 3 seconds.
7,
Motor is being started too frequently
Excessive starting will damage motor capacitors. Contact motor manufacturer if
motor is started more than 20 times/hour or if acceleration time exceeds 3
seconds.
,
Motor voltage low
Verify that voltage at the motor terminals is within limits (see section 3.4.1.3).
?,
Defective start switch inside motor
Motor internal switch failure overheats start capacitor. Contact service shop or
motor manufacturer.
$
,
,
High ambient temperature
Verify that the ambient does not exceed motor’s nameplate value
