Testing The Insulation Resistance And Polarization Index - Siemens SIMOTICS A 1FU8 Operating Instructions Manual

5.3.3.2

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
for the insulation resistance meter you are going to use.
2. Make sure that no power cables are connected.
3. Measure the winding temperature and the insulation resistance of the winding in relation
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.
4. Read out the insulation resistance one minute after applying the measuring voltage.
Limit values for the stator winding insulation resistance
The following table specifies the measuring voltage and limit values for the insulation
resistance. These values correspond to IEEE 43-2000 recommendations.
Table 5- 1
U
rated
U
meas
R = minimum insulation resistance at reference temperature of 40° C
C
1FU8
Operating Instructions, 02/2016, 5 610 70000 02 000
WARNING
delivered.
following measures:
– Connect the terminals with the ground potential until the recharge voltage drops to a
non-hazardous level
– Attach the connection cable.
Stator winding insulation resistance at 40° C
V [V]
N
U ≤ 1000
1000 ≤ U ≤ 2500
2500 < U ≤ 5000
5000 < U ≤ 12000
U > 12000
= rated voltage, see the rating plate
= DC measuring voltage
5.3 Preparing for installation
V [V]
Meas
500
500 (max. 1000)
1000 (max. 2500)
2500 (max. 5000)
5000 (max. 10000)
Assembly
R [MΩ]
C
≥ 5
100
39