Procedures for Testing with the DX Host
megger.com 85
Partial Discharge Testing–Three-phase Coil Mode
PD testing follows a similar procedure to Surge testing. If you are not already there, ensure that
the tester is in Surge testing mode.
1. For this example, touch the Standalone Unit icon then the Coil Mode Selection icon
in the Mode Submenu.
2. From the Popup Menu, select the Three-phase coil mode icon.
3. The Lead Selection icons default to coil 1 to start the test.
4. Touch the Enable PD icon on the right side of the screen. This activates the detector
circuit and tells the tester to display PD data on the surge graph.
NOTE: When Enable PD is pressed the first time, the screen will not update to PD specific fields. This
happens when the PTT button is first pressed after enabling the feature.
Figure 93. Enabling PD testing adds elements to the start screen.
The PD event threshold field (PD threshold [mV] set in the User Settings screen) shows the
voltage level of the PD signal detected— value displayed in millivolts.
The PD events detected / PD number of events field shows the number of PD events that
exceeded the PD number of events value (PD # events set in the User Settings screen). When the
PD events detected value exceeds the PD number of events value, a red PD indicator will appear
just outside the left edge of the X axis, indicating that a PD pulse has occurred.
The PD signal samples per display pixel field shows the number of PD signal samples
gathered per display pixel and indicates the resolution of the displayed PD waveform. The PD
measurement system is approximately five times faster than the surge measurement system, so
more PD signals are measured within a surge than can actually be displayed. The measurement
is faster because PD detection is measuring higher frequency information.
5. Hold down the PTT button and use the Voltage Output Control knob to ramp up the
voltage slowly and evenly.
6. Touch the Fast Ramp Rate icon to ramp at the higher rate if desired, but ensure that
ramping is slow enough to allow observation of PD events as described above.
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