2015 Jicable - Risk On Failure Based On PD Measurements in Actual MV PILC and XLPE Cables.
2015 Jicable - Risk On Failure Based On PD Measurements in Actual MV PILC and XLPE Cables.
2015 Jicable - Risk On Failure Based On PD Measurements in Actual MV PILC and XLPE Cables.
Alternatively, it is possible that SCG was removed before is necessary to plot the probability charts for XLPE and
a fault happened. The data related to such cases is called PILC cables individually. Figure 1 and Figure 2 show the
censored data. A case is censored if the failure time is cumulative failure probability of XLPE cables, respectively
unknown but it is known that the item survived to a known from the start of the PD activity and from the moment a
time without failure. warning of the highest level was given based on the SCG
The cases where both the start of PD activity is known knowledge rules. Figure 3 and 4 show the same for PILC
and the breakdown moment is known are called cables.
uncensored data.
XLPE cable results
Many papers and books introduce Weibull statistics. As a
reference, one out of the many, the Wikipedia reference is
given here [7] and also a handbook [8]. Figure 1 is based on XLPE data. There are 20 breakdown
cases or almost breakdown cases (uncensored data) and
Data selection 11 cases of weak spots that didn't fail (while monitored
with SCG), the censored cases.
With SCG the PD activity could be observed, but for the In Figure 2, instead of the start of PD activity, the start of
analyses there are four different situations: an SCG warning for the XLPE cable cases is taken for the
analyses. Such an SCG warning is normally given after
1. after SCG was installed, the PD activity started and did the SCG operating experts consider the PD activity (level,
run to a failure also observed by SCG (this is the most repetition rate and growth over time) such that “soon” a
wanted situation); breakdown is expected.
2. after SCG was installed, the PD activity started and
didn’t run (yet) to a failure observed by SCG;
3. before SCG was installed, the PD activity started and
did run to a failure also observed by SCG;
4. before SCG was installed, the PD activity started and
didn’t run (yet) to a failure observed by SCG.
THE AVERAGE TIME BETWEEN THE START Fig.2: Failure probability for XLPE, based on the time
OF PD ACTIVITY AND A FAULT until failure after an SCG warning; the red line shows
the 50 % chance on a failure, being 10 days (no
Introduction confidence bounds are given).
Due to the self-healing ability of PILC cables in contrast to
XLPE, there is a big difference on survival times after first
PD activity occurs between XLPE and PILC cables. So, it