Megger Power Diagnostix ICMflex User Manual page 71

ICMflex
Partial discharge and loss factor measurement system
polarities at the end of the dead time ('Peak Pol.'). Additionally, the ICMflex2 offers an AND combination of
both methods ('F&P Pol.'). The effectiveness of these methods is depending on the repetition rate and the
amplitude ratio of the two pulse sources. If there is a high repetition rate, the 'First Pol.' method has a problem
if a large disturbance pulse follows a smaller PD pulse. If the amplitude of both pulse sources is very different,
the 'Peak Pol.' method has a problem, if one pulse is over ranged in both polarities because the peak ampli-
tudes cannot be compared. Several examples of pulse polarity detection cases are shown with Figure 96 to
Figure 99.
The calibration and PD measurement is usually done with the main channel. If 'Switch to Active Setup' is
selected for 'DSO & Scope View' within the preferences (see Figure 93), the corresponding screens of the
PD and LOC display can also show the auxiliary channel. But there is no calibration possible, the amplitude
is shown in percent. For the upper right-hand screen, it is possible to choose, if the scope view displays the
acquisition pattern or the disturbance pattern. The lower right-hand screen always shows the acquisition
pattern.
To view the shape of the pulses used for the pattern choose 'IEC 60270' for 'DSO Bandwidth' in the mul-
ti-channel options of the preferences (see Figure 93). In IEC 60270 mode the DSO shows the filtered signal
used for the pattern and the polarity decision. In this mode only the PD gain is relevant.
pdix.com User guide for ICMflex
71