MI 3102(H) BT EurotestXE Measurements
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5.3 The DAR and PI diagnostic (MI 3102H BT only)
Analysing the changes in the measured insulation resistance over time and calculating the DAR
(Dielectric Absorption Ration) and PI (Polarization Index) are very useful maintenance tests of
insulating materials.
Diagnostic test is a long duration test for evaluating the quality of the insulation material under
test. The results of this test enable the decision to be made on the preventive replacement of
the insulation material.
DAR is ratio of insulation resistance values measured after 15 seconds and after 1 minute. The
DC test voltage is present during the whole period of the measurement.
s 15
min 1
DAR
R
R
iso
iso
PI is the ratio of insulation resistance values measured after 1 minute and after 10 minutes. The
DC test voltage is present during the whole period of the measurement
min 1
min 10
PI
R
R
iso
iso
For additional information regarding PI and DAR diagnostic, please refer to Metrel’s handbook
Modern insulation testing.
See chapter 4.2 Function selection for instructions on
key functionality.
Figure 5.9: Diagnostic tests menu
Test parameter for diagnostic tests
Nominal test voltage [500 V, 1000 V, 2500 V]
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