LEESON Permanent Magnet AC Motors - Manual (Page 9)

with pacemakers, hearing aids, or other implanted electronic medical
devices and may impact other electronic devices such as mobile phones,
credit cards, etc.
WARNING: ELECTRICAL SAFETY
Refer to Section 1.0 for additional warnings before proceeding with
maintenance.
4.1 GENERAL INSPECTION
Inspect the motor approximately every 500 hours of operation or every
three months, whichever occurs first. Keep the motor clean and the
ventilation and fin openings clear. The following steps should be
performed at each inspection:
4.1.1 VENTILATION : Check that the ventilation openings and/or
exterior of the motor are free of dirt, oil, grease, water, etc, which
can accumulate and block motor ventilation. If the motor is not
properly ventilated, overheating can occur and cause early motor
failure.
4.1.2
INSULATION : To monitor motor insulation, disconnect
motor from the VFD and use a “Megger” to take periodic readings.
Record the Megger readings. If winding resistance to ground is less
than 1.5 Meg-ohms consult the local authorized service shop before
re-energizing the motor.
4.1.3 ELECTRICAL CONNECTIONS: With all power off and
motor stopped, check all electrical connectors to be sure that they
are tight.
4.1.4 SEAL CONDITION: When supplied, check the condition
of shaft seals and replace if necessary.
4.1.5 SAFETY LABELS: Do not remove or cover safety labels.
Inspect and clean safety labels to maintain visibility. Replace labels
if they are no longer readable.
4.2 LUBRICATION & BEARINGS
The lubricating ability of 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. Longer bearing
life can be obtained if the listed recommendations are followed:
NOTE: If lubrication instructions are provided on the motor nameplate,
the nameplate instructions will supersede these instructions. Motors
marked “Permanently Lubricated” do not require additional service”.
NOTICE: BEARING / MOTOR DAMAGE
Lubricant should be added at a steady state of moderate pressure. If
added under heavy pressure, bearing shield(s) may collapse. Over
greasing bearings greatly increases bearing friction and can cause
premature bearing and/or motor failure.
4.2.1 GREASE TYPE (unless nameplate states otherwise)
Nameplate Ambient Temperature between -30°C (-22°F) to 65°C
(150°F) inclusive: Recommended grease for standard service
conditions is Polyrex EM (Exxon Mobil). Equivalent and compatible
greases include: Texaco Polystar RB, Rykon Premium #2, Pennzoil
Pen 2 Lube, Chevron SRI & Mobil SHC 100.
Nameplate Ambient Temperature below -30°C (-22°F ):
Special
low temperature grease is recommended, such as Aeroshell 7 or
Beacon 325 for ball bearings and Mobil SHC 100 for roller bearings.
Nameplate Ambient Temperature above 65°C (150°F ): Dow
Corning DC44 or equivalent, a special high temperature grease is
required. Note that Dow Corning DC44 grease does not mix with
other grease types.
4.2.2
BEARING OPERATING TEMPERATURE
CAUTION: HOT SURFACE
The external surface temperature of the end shield (bracket)
bearing hub may reach 100° C (212° F) during normal operation.
Touching this surface may cause discomfort or injury. Surface
temperatures should only be measured with suitable instruments
and not estimated by hand touch.
For RTD settings see Table 3-7.
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4.2.3
LUBRICATION INTERVALS (For motors with regreasing provisions)
Eq. 4.2 Lubrication Interval = [(Table 4-1) hrs] x [Interval Multiplier (Table 4-2)] x [Construction Multiplier (Table 4-3)]
Recommended lubrication intervals are shown in Table 4-1. These values are based on average use.
Table 4-1 Lubrication Intervals
NEMA / [IEC] Frame Size
Operating Speed – RPM (See Table 3.4 for Maximum Operating Speed)
<7200 <5400 <4500 <3600 <1800 <1200
180 [110] 2500 Hrs. 4000 Hrs 5000 Hrs 6000 Hrs. 17000 Hrs. 20000 Hrs.
210-250 [130-160] 2500 Hrs 4000 Hrs 5000 Hrs. 12000 Hrs. 16000 Hrs.
280 [180] 2000 Hrs 3000 Hrs 4000 Hrs. 10000 Hrs. 14000 Hrs.
Seasonal Service: If motor remains idle for more than six months, Lubricate at the beginning of the season, then follow lubrication interval.
Do not exceed maximum safe operating speed without manufacturer’s approval
Table 4-2 Service Conditions
Use highest level Multiplier : Maximum Ambient Temperature and Contamination are independent factors
Severity of
Service
Maximum Ambient
Temperature
Atmospheric Contamination Multiplier
Standard Less than 40° C (104° F) Clean, Slight Co rrosion, indoors, less than 16 hrs per day
1.0
Severe
Above 40° C (104° F) to 50°
C
Moderate dirt or Corrosion or outdoors or more than 16 hrs
per day 0.5
Extreme
Greater than 50° C or
Class H Insulation
Severe dirt or Abrasive dust or Corrosion 0.2
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