34
Motor
Manual
10 Maintenance
10.1 General
Motors must be maintained. Neglecting motor maintenance
will degrade the performance and lifetime of the motor.
Proper installation, electrical/thermal protection and correct
maintenance of a motor result in optimal motor life.
Inspect the motor at regular intervals, keep the motor clean,
ensure a free flow of ventilation air, and check the condition
of shaft seals and replace them as necessary. It is important
that the shaft seals are always intact. Check the electrical
connections and mechanical mounting, and tighten termi-
nals and fasteners as necessary.
All maintenance work on motors must be performed by
suitably qualified personnel.
• Voltage can be present inside the terminal box when
the motor is not running, for example if the motor has
a heating strip or direct winding heating. Always switch
off auxiliary power and protect against reactivation be-
fore carrying out maintenance on the motor.
• A motor operating from a VFD can be electrically live
even when it is not running.
• Capacitors in single-phase motors can retain a charge
over the motor terminals even when the motor is not
energised.
• Be aware of rotating parts.
• Grease can cause eye and skin irritation. Follow the
safety instructions of the grease manufacturer.
• Do not exceed the maximum permissible speed of the
motor.
• Do not exceed the maximum operating temperature of
the grease and the bearings.
Clean the exterior of the motor at regular intervals, taking
the IP rating of the motor into account.
If the motor operates in an environment where the fan cov-
er ventilation openings or the cooling fins can be obstruct-
ed, the obstructions must be removed. Any deviation from
nominal motor performance or irregular motor operation
(e.g. increased motor current, temperature above the per-
mitted value for the stated insulation class, increased vibra-
tion, unusual noises, noticeable insulation odour, tripped
motor protection devices, etc.) must be investigated care-
fully to determine the cause.
For spare parts, contact Hoyer Motors with the exact motor
type and serial number from the motor nameplate.
10.2 Bearings and re-greasing
The standard bearing assembly is single row deep-grove
ball bearings (ZZ or 2RS) with clearance C3. The bearings
(ZZ or 2RS) are lubricated for life. Bearing replacement in
the event of failure or noise, or at regular service intervals,
must be performed with adequate tools and without apply-
ing excessive force or hammering.
Open bearings must be re-greased. Open the grease outlet
if the plug has been closed. It is recommended to grease
for the first time during commissioning. The following ap-
plies in general for both lifetime lubricated bearings and re-
lubricated bearings:
• With 60 Hz operation the grease lifetime will be re-
duced by approximately 20%.
• The values for vertically mounted motors are half of
the stated values. The values in the tables are based on
an ambient temperature of 25°C (Table 14 and Table 15).
• The grease lifetime is reduced by 50% for every 15 K rise
in bearing temperature.
• Operation at higher speeds, e.g. with a variable speed
drive, makes shorter regreasing intervals necessary.
Doubling the speed will typically reduce the grease life-
time by 50%.
If re-greaseable bearings are fitted, observe the re-greasing
intervals in Table 15, Re-greasing intervals and amounts.
Re-greasing of the bearings while the motor is in operation
is possible via the grease nipples on the bearing shields,
using a hand grease gun for a consistent grease amount.
Hoyer recommends the following greases for use in the am-
bient temperature range of -20°C to +150°C: Polyurex EM2
or other polyurea based grease with a drip temperature of
180-200°C. If other grease types are used it must have the
same or better NLGI grade and consist of same thickener
base, otherwise compatibility must be checked with grease
manufacturer.
The bearing size and type are shown on the nameplate,
and an overview is provided in Section 6.2. Motor types
HMA3 and HMAC3 are equipped as standard with lifetime
greased bearings in frame sizes up to 180 with cast iron and
up to 132 with aluminium. Motor types HMA2 and HMC2
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