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equipment

Keep humidity in check For storage purposes, any motors with sleeve be-
arings need to be filled with the correct quantity of
Motors supplied with space heaters should be oil as they are normally supplied dry. After every
stored with them switched on to avoid humidity two months of storage, the shaft should be rota-
condensation inside the motor. This is achieved by ted at about 30 rpm for oil circulation. If it is not
maintaining the inner temperature of stored motors possible to rotate the shaft, further instructions for
at around 2-3ºC above ambient temperature. maintaining contact surfaces free of corrosion must
The motor’s insulation resistance is another area be consulted in the motor’s manual. Starting the
of concern. After prolonged storage, winding in- motor after a long storage period without correct
sulation resistance needs to be measured before care of the bearing system can cause failure and
operating the motor. If the ambient atmosphere the destruction of the sleeve bearings.
has high levels of humidity, these measuring tasks
needs to be periodic. Limit values defined by IEEE-
43 must be checked. If the test is performed at a Conduct thorough periodic
temperature different to 40ºC, it is necessary to inspections to evaluate motor
correct the value according to IEEE-43 correction
curves. condition
When checking for winding insulation resistance, In all cases, periodic motor inspections should be
the terminal boxes should also be observed to see conducted for any signs of physical damage, con-

Image 2: The correct installation and operation of flameproof motors is essential to maximise the life expectancy of ma-
chinery operating in hazardous environments

if: the interior is dry and free of any dust accumula- For storage purposes, any
tion; the contact elements are free of corrosion; the motors with sleeve bearings
flameproof joint is free of corrosion and any kind of
damage or scratches; and the cable inlets are cor- “need to be filled with the correct
rectly sealed with certified cable glands (or certified quantity of oil as they are
plugs if not in use). normally supplied dry

Protect joints and surfaces
from corrosion tamination or the presence of water condensation
or other aggressive agents. Checking ambient and
Flameproof joints need to be free of corrosion. winding temperatures, relative humidity, and re-
Therefore, prior to assembly following prolonged cording the vibrations during storage, are vital to
storage, the enclosure’s flameproof joint surfaces achieving a correct evaluation of a motor’s status
must be protected against corrosion with grease. before start-up.
Similarly, with motor bearings, any prolonged sto- Following long-term storage, the motor should be
rage periods make it necessary to remove the shaft cleaned and dried before start-up. The corrosion
locking device and rotate the shaft manually every inhibitor of exposed machined surfaces, such as
two months. After rotation, the end position of the the shaft end, must be removed using a cloth soa-
shaft should be 45º from its initial position. For sto- ked in petroleum-based solvent. It must also be
rage times greater than six months, the bearings guaranteed that any enclosure entry is fitted with a
will require greasing before start-up. certified plug, drain or cable gland depending on its

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