16BCommissioning
Standard motors
56100000002001, 02/2013
53
insulation resistance value close to the minimum value could be due to moisture
and/or dirt accumulation.
● During operation, the insulation resistance of the windings can fall to the critical
insulation resistance due to ambient and operational influences. The critical
insulation resistance value for a winding temperature of 25 °C can be calculated
by multiplying the rated voltage (kV) by the specific critical resistance value
(0,5 MΩ / kV).
Example:
Critical resistance for rated voltage U
N
= 690 V:
690 V x 0,5 MΩ / kV = 0,345 MΩ
Note
Critical insulation resistance reached or fallen below
If the critical insulation resistance is reached or fallen below, this can result in
damage to the insulation or voltage flashovers.
● Contact your Siemens Service Center.
● If the measured value is close to the critical value, you must check the
insulation resistance at suitably frequent intervals.
Measures before commissioning
Once the system has been correctly installed, you should check the following prior to
commissioning:
● The machine has been assembled and aligned correctly.
● The machine has been connected so that it rotates in the direction specified.
● The operating conditions match the data specified on the rating plate.
● The bearings have been lubricated as appropriate for the version used. Rolling-
contact bearing machines which have been in storage for more than 24 months
have been relubricated.
● Any supplementary machine monitoring equipment has been connected correctly
and is functioning as it should.
● For versions with bearing thermometers, the bearing temperatures must be
checked during the machine's first period of operation. The warning and
shutdown values are set on the monitoring device.
● Appropriately configured control and speed monitoring functions ensure that the
machine cannot exceed the permissible speeds specified on the rating plate.
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