DC motor - Siemens, s.r.o.

Note
4.4 Energizing
Commissioning
After drying a cleaned winding, note that the insulation resistance is lower for warm
windings.
The insulation resistance can only be meaningfully evaluated if measurements are
taken after the winding has cooled down to room temperature (20 to 30 °C).
Over its operating lifetime, the motor winding insulation resistance can drop due to
ambient and operational influences. The critical insulation resistance for a 25°C
winding temperature can be calculated, depending on the rated voltage, by
multiplying the rated voltage (kV) by the specific resistance given in the above
table.
e.g. critical resistance for UN = 400 V : 0.4 kV x 0.5 MΩ/kV = 0.2 MΩ
If the calculated critical insulation resistance value is reached or undershot, the
windings must be thoroughly cleaned and dried. If the measured value is close to
the minimum value, the insulation resistance should be subsequently checked at
appropriately shorter intervals.
[ID 552]
Recommended measures
•= Start the motor briefly without any load coupled - check the direction of rotation.
•= As the motor runs down, check the mechanical running for noises or vibrations
in the bearings and bearing end shields.
•= If there are no problems with the mechanical running, energize the motor again
and run it up to maximum permissible speed (according to the rating plate).
•= If it is running irregularly or emitting abnormal noises, deenergize the motor and
determine the cause as it runs down.
•= If the mechanical operation improves immediately after switching the motor off,
then the cause is magnetic or electrical.
•= If the mechanical running does not improve after deenergizing, there are
mechanical causes (e.g. electrical machines out of balance, etc.).
•= If the motor is running perfectly, switch on the available cooling system.
•= Observe the motor for a period of time at no load.
Note
Shorten the energizing time accordingly if you do not intend to operate the air-towater
heat exchanger in an "advance" test run.
•= When the motor is running perfectly, apply a load – check smooth running.
Record the values for voltage, current and output. If possible, record the
corresponding values for the driven machine.
SIEMENS AG T61160347010001 (DMHO V9)
Operating instructions 1GG6286-0NA4.-1VV1-Z 4-5