Omicron CP CR500, User Manual

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Diagnostic of Rotating Machines Insulation
6.3 The Dielectric Response of Winding Insulation
With the dielectric response measurement at low test voltages, the general
insulation aging and the water content in the insulation can be checked.
Figure 6-6:
Dielectric response of
the winding insulation
The test is made at low test voltages of about 100 V to 200 V from 15 Hz to
400 Hz. In this case also high capacitance can be tested without compensating
reactors. The value at rated frequency (50 / 60 Hz) can be compared to the value
at test frequency of e.g. 55 Hz, which is used to get resonance with the
compensating reactor coil.
0.25 %
0.35 %
0.45 %
0.55 %
0.65 %
0.75 %
0.85 %
0.0 Hz 100.0 Hz 200.0 Hz 300.0 Hz 400.0 Hz 500.0 Hz
Ta
n D
elt
a
low w ater content
medium w ater content
high w ater content