Detailed information on testing and the limit values can be found here:
"Testing the insulation resistance and polarization index" (Page 51)
Testing the insulation resistance and polarization index
Hazardous voltage at the terminals
During and immediately after measuring the insulation resistance or the polarization index
(PI) of the stator winding, hazardous voltages may be present at some of the terminals.
Contact with these can result in death, serious injury or material damage.
● If any power cables are connected, check to make sure line supply voltage cannot be
● Discharge the winding after measurement until the risk is eliminated, e.g. using the
Measure the insulation resistance
1. Before you begin measuring the insulation resistance, please read the operating manual
2. Make sure that no power cables are connected.
3. Measure the winding temperature and the insulation resistance of the winding in relation
4. Read out the insulation resistance one minute after applying the measuring voltage.
SIMOTICS TN Series N-compact 1LA8
Operating Instructions 08/2017
– Connect the terminals with the ground potential until the recharge voltage drops to a
– Attach the connection cable.
for the insulation resistance meter you are going to use.
to the machine enclosure. The winding temperature should not exceed 40° C during the
measurement. Convert the measured insulation resistances in accordance with the formula
to the reference temperature of 40° C. This thereby ensures that the minimum values
specified can be compared.
5.1 Preparations for installation