Megger Baker DX, User Manual

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Using Baker DX Non-Test Functions
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Setting Parameters for Partial Discharge Testing
Partial discharge measurements—and their resulting indications—are dependent on the
magnitude and intensity of activity that you want or need to measure. The magnitude of the
partial discharges refers to the PD threshold level (also referred to as
PD event threshold —set
in millivolts), a minimum level that the discharge activity reaches or exceeds during any given
pulse to qualify as PD. The frequency or intensity of the partial discharge refers to the amount of
activity (number of PD events—
PD # events ) occurring during any given surge pulse. A
combination of these two metrics determines what level of partial discharge is considered
significant for the unit being tested.
These levels are set in the User Settings screen under the PD settings heading on the lower left
portion of the screen.
NOTE: For more information on partial discharge testing, refer to the Megger Motor Testing Theory
Reference Manual.
Figure 48. PD settings in User Settings screen.
Coils rated for higher voltages will exhibit higher magnitudes of PD than coils rated for lower
voltages, so this setting should be adjusted in accordance with the nameplate voltage rating of
the coil, the baseline noise level of the PD signal, and the surge voltage to be used for testing.
NOTE: The first pulse is due to the higher frequency of the square wave of the initial voltage drop across the
coil. For this reason, we recommend setting the PD # events value no lower than 2.