There are several well-known approaches of Partial Discharge (PD) analysis. The most common
ones are: The use of Phase Resolved Partial Discharge (PRPD), with the PD charge over the phase angle
The PD trend over time
The PD charge dependency of the high voltage (Q(U))
Statistical TDR (sTDR) for localization, where the travelling times in a cable are used to determine the PD position
New approaches introduced by OMICRON are the use of multi-band measurements on one MPD unit for single phase source discrimination (3CFRD/3FREQ) and the use of time synchronous measurements on hree measurement units connected to all three phases of a test object (3PARD).
Phase Resolved Partial Discharge (PRPD) is a well-known tool which provides the possibility to analyze the faults with respect to the phase of the applied voltage. Additional information can be obtained by taking into account the position of the PD pulses in reference to the phase of the voltage.
Changes in the PD behavior over time may indicate changes of the PD fault. For instance, some international standards limit the allowed rise of charge during a test to a certain limit.
Q(U) will form a graph that shows the relationship between test voltage level and PD charge magnitude. Figure 3 shows examples of real PD measurements.
For fault localization on power cable, OMICRON supports two methods , namely the Time Domain Reflectometry (TDR) and the Statistical TDR (sTDR). Signal propagation along a medium voltage/ high voltage cable system can be very complex, thus analyzing the test results is one of the main challenges. TDR is a very well-known tool. However there are limitations in noisy situations with multiple reflections. The sTDR is more robust in noisy environments and can visualize the multiple reflection points.
For technical enquiries, please contact Seokhoon Hong (Regional Application Specialist – Partial Discharge) via email firstname.lastname@example.org or Contact ENTEC A&T’s email: email@example.com