Megger Baker DX, User Manual

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Procedures for Testing with the DX Host
megger.com 83
Checking and Recording System Noise Level
The DX Partial Discharge feature includes the ability to measure and record the level of system
noise present for different test setups. Different coils and stators, along with the difference in
overall noise in the earth ground, will present different noise signals that should be recorded to
determine the sensitivity of the Partial Discharge detector. The threshold for PD event magnitude
must be above this value to function correctly.
NOTE: To record the system level noise, follow the procedure below. This procedure should be followed for
every different load for the most accurate PD records.
1.
Connect the test leads to the device under test as normal for a Surge test in three-phase
coil mode or single-coil mode as needed.
2.
Apply just the initial surge voltage to the device (do not ramp up). Keeping the voltage
low ensures that no PD is present on the load.
3.
Observe the magnitude of the PD signal in comparison to the threshold value and
position on the display.
4.
Enter into maintenance mode (not admin mode) and adjust the user setting PD
threshold (mV)
so that the PD signal is just below or just exceeding the threshold
indicator line. Press the PD/Temp Settings button then the PD threshold button in
the popup menu to change the PD threshold (mV) value.
Figure 90. User Settings screen, PD value settings menus.
5.
Return to the surge screen.
6.
Again, apply just the initial surge voltage to the device (do not ramp up).