DC motor - Siemens, s.r.o.

Commissioning
Checking the insulation
The insulation resistance of the windings with respect to the motor frame must be
checked with DC voltage before the motor is put into operation for the first time and
after a lengthy period of storage or standstill.
Measuring-circuit voltage
The maximum permissible measuring-circuit voltage for measuring the insulation
resistance on electrical components is basically 500 V.
A measuring-circuit voltage of 1000 V is permissible in an exceptional case for new
windings only, provided that previously the insulation resistance has been
measured with a measuring-circuit voltage of max. 500 V and the insulation value
was not lower than the permissible value.
When taking the measurement, you must wait until the measured value remains
constant.
Warning
After the measurement the electrical components must be discharged by being
grounded.
Minimum insulation resistance
Table 4-1 Minimum insulation resistance (for winding temperature of 25°C)
Value
Measuring-circuit voltage 500 V (min. 100 V)
Minimum insulation
10 MΩ
resistance with new, cleaned
or repaired windings
Critical specific insulation
resistance after a long
operating time
Insulation resistance
0.5 MΩ/kV
Dry, new windings have insulation resistances of between 100 and 2000 MΩ, or
possibly even higher values. If the insulation resistance is close to the minimum
value, then the cause could be either humidity and/or dirt accumulation. If the
insulation resistance falls below the minimum value, determine the cause, and
clean and dry the winding.
SIEMENS AG T61160347010001 (DMHO V9)
4-4 Operating instructions 1GG6286-0NA4.-1VV1-Z