Operating Instructions – Explosion-Proof AC Motors – DRS/DRE/DRP 315
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4
Mechanical installation
Mechanical Installation
Extended storage
of motors
• Note that the service life of the lubricant in the ball bearings is reduced by 10% per
year after the first year of storage.
• You should re-lubricate the lubrication devices on motors that have been in storage
for longer than 5 years before startup. Observe the information on the motor lubricant
plate.
• Check whether the motor has absorbed moisture as a result of being stored for a long
time. Measure the insulation resistance for this purpose (measuring voltage 500 V).
The insulation resistance (see following figure) varies greatly depending on the
temperature. The motor must be dried if the insulation resistance is not adequate.
Drying motor
Heat the motor:
• with warm air or
• via isolation transformer
– Connect windings in series (see following figure)
– Auxiliary alternating current max. 10% of the rated voltage with max. 20% of the
rated current
The drying process is finished when the minimum insulation resistance has been ex-
ceeded.
Check the terminal box for the following:
• dry and clean inside
• Connection and fastening elements corrosion free
• Gasket and sealing surfaces OK
• Cable glands are sound, otherwise clean or replace them
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