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Note

Comment to IEEE43

According to IEEE43, also for winding temperatures <40°C, R

must be converted over to the

reference temperature of 40°C.

As the minimum values for R

apply at 40°C, the required R

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 1and

10minutes.

2. Express the measured values as a ratio:

Polarization index=R



10min

/R



1min

Many measuring devices display these values automatically following the measurement.

Measuring the polarization index is not helpful for insulation resistances >5000MΩ, and is

therefore not included in the assessment.



10min

/R

i1min

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.

• If the measured value is close to the critical value, you must subsequently check the

insulation resistance at shorter intervals.

Siemens SIMOTICS SD User Manual

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