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5.2.2
Insulation resistance and polarization index
Measuring the insulation resistance and polarization index (PI) provides information on the
condition of the machine. It is therefore important to check the insulation resistance and the
polarization index at the following times:
● Before starting up a machine for the first time
● After an extended period in storage or downtime
● Within the scope of maintenance work
The following information is provided regarding the state of the winding insulation:
● Is the winding head insulation conductively contaminated?
● Has the winding insulation absorbed moisture?
As such, you can determine whether the machine needs commissioning or any necessary
measures such as cleaning and/or drying the winding:
● Can the machine be put into operation?
● Must the windings be cleaned or dried?
Detailed information on testing and the limit values can be found here:
"Testing the insulation resistance and polarization index" (Page 53)
5.2.3
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 for
2. Short-circuit the ends of the temperature sensor cables before applying the test voltage. If
SIMOTICS FD 1MM1
Operating Instructions 02/2019
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.
the insulation resistance meter you are going to use.
the test voltage is connected to only one temperature sensor terminal, the temperature
sensor will be destroyed.
Assembly
5.2 Preparations for installation
53
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