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5.1.3
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.
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
SIMOTICS TN Series N-compact 1LH8
Operating Instructions 06/2017
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.
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.
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
5.1 Preparations for installation
V
[V]
Meas
500
500 (max. 1000)
1000 (max. 2500)
2500 (max. 5000)
5000 (max. 10000)
Assembly
R
[MΩ]
C
≥ 5
100
45
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