Baldor MN605, Installation And Operating Manual

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3-1 MN605
Section 3
Maintenance & Troubleshooting
General Inspection
Inspect the motor at regular intervals, approximately every 500 hours of operation or every 3 months, whichever
occurs first. Keep the motor clean and the ventilation openings clear. The following steps should be performed at
each inspection:
1. Check that the motor is clean. Check that the interior and exterior of the motor is free of dirt, oil, grease,
water, etc. Oily vapor, paper pulp, textile lint, etc. can accumulate and block motor ventilation. If the motor is
not properly ventilated, overheating can occur and cause early motor failure.
2. Periodically measure the motor winding resistance to ensure that the integrity of the winding insulation has
been maintained. Record the motor winding resistance. Immediately investigate any significant drop in
insulation resistance.
3. Check all electrical connectors to be sure that they are tight.
4. Check for too much vibration or looseness. It may be caused by improper alignment, an unbalanced
coupling sheave, damaged motor bearings, or loose mounting bolts. Excessive vibration will damage the
motor bearings, brushes and commutator.
5. Listen for unusual noises, especially in the area of the bearings. Also, rubbing or rumbling noises could
be signs of internal damage. Check for loose parts on the motor such as thru bolts, hold down bolts, bad
alignment of hoods, etc. An unbalanced armature or load may also cause noise.
Note: Motors applied with rectified power supplies will often make a humming noise when operating normally. This
is even more noticeable at lower operating speeds. If you can hear a growling or erratic hum, the power
supply should be checked for proper operation and phase balance. Improper adjustment or functioning of
the power supply can cause overheating of the motor and shorten its life.
6. At start−up, check the tightness of the main and commutating pole bolts (external on the frame) as listed in
Table 3-1. Loose pole bolts could be a source of unpleasant noise when rectified power runs the motor.
Table 3-1 Torque Specifications for Commutating and Main Pole Bolts
Frame Bolt Size Torque (lb-ft)
180AT 3/8 - 16 24 - 30
210AT 3/8 - 16 24 - 30
250AT 3/8 - 16 24 - 30
280AT 1/2 - 13 60 - 75
320AT 1/2 - 13 60 - 75
360AT 3/8 - 16 24 - 30
400AT 3/8 - 16 24 - 30
500AT 1/2 - 13 60 - 75
Lubrication & Bearings
Bearing grease will lose its lubricating ability over time, not suddenly. The lubricating ability of a grease (over time)
depends primarily on the type of grease, the size of the bearing, the speed at which the bearing operates and the
severity of the operating conditions. Good results can be obtained if the following recommendations are used in
your maintenance program.
Type of Grease
A high grade ball or roller bearing grease should be used. Recommended grease for standard service conditions
is Polyrex EM (Mobil).
Equivalent and compatible greases include:
Texaco Polystar, Rykon Premium #2, Pennzoil Pen 2 Lube and Chevron SRI−2.
− Maximum operating temperature for standard motors = 110° C.
− Shut−down temperature in case of a malfunction = 115° C.
Lubrication Intervals
Recommended lubrication intervals are shown in Table 3-2. It is important to realize that the recommended
intervals of Table 3-2 are based on average use. Refer to additional information contained in Tables 3-3 and 3-4.
Table 3-2 Lubrication Intervals *
NEMA / (IEC) Frame Size Base Speed - RPM
>2500 1750 1150 <800
Up to 210 incl. (132) 5500 Hrs. 12000 Hrs. 18000 Hrs. 22000 Hrs.
Over 210 to 280 incl. (180) 3600 Hrs. 9500 Hrs. 15000 Hrs. 18000 Hrs.
Over 280 to 360 incl. (225) * 2200 Hrs. 7400 Hrs. 12000 Hrs. 15000 Hrs.
Over 360 to 500 incl. (300) *2200 Hrs. 3500 Hrs. 7400 Hrs. 10500 Hrs.
* Lubrication intervals are for ball bearings. For roller bearings, divide the listed lubrication interval by 2.