Note
Comment to IEEE43
According to IEEE43, also for winding temperatures <40°C, R
i
must be converted over to the
reference temperature of 40°C.
As the minimum values for R
i
apply at 40°C, the required R
i
values are somewhat higher for
winding temperatures below 40°C.
Measuring the polarization index
1. To determine the polarization index, measure the insulation resistances after 1and
10minutes.
2. Express the measured values as a ratio:
Polarization index=R
i
10min
/R
i
1min
Many measuring devices display these values automatically following the measurement.
Measuring the polarization index is not helpful for insulation resistances >5000MΩ, and is
therefore not included in the assessment.
R
i
10min
/R
i1min
Assessment
≥2 Insulation in good condition
<2 Dependent on the complete diagnosis of the insulation
NOTICE
Damage to insulation
If the critical insulation resistance is reached or undershot, this can damage the insulation and
cause voltage ashovers.
• Contact the service center (Page12).
• If the measured value is close to the critical value, you must subsequently check the
insulation resistance at shorter intervals.
See also
Insulation resistance and polarization index (Page49)
Limit values of the anti-condensation heating insulation resistance
The insulation resistance of the anti-condensation heating with respect to the machine housing
must not be lower than 1MΩ when measured at 500VDC.
Assembly
5.2Preparing for installation
1LE1, 1FP1/3, 1PC1/3 shaft height 63 ... 315
52 Operating Instructions, 11/2023, A5E38483075A