How does coupling capacitance affect PD detection sensitivity?

The PD detection sensitivity is linked to the ratio of the coupling capacitor to the capacitance of the test object, as an increase in sample capacitance eventually reduces detection sensitivity. In other words, by increasing the coupling capacitance, it is possible to increase the measurement sensitivity and SNR.

What is a coupling capacitor?

The Coupling Capacitor is a highly sensitive partial discharge (PD) sensor used to decouple PD from the monitored conductor. Coupling Capacitors are installed as close to the winding as possible for maximum sensitivity. Applications include generators, switchgear, motors, Iso-phase bus and transformers.

How does a coupling capacitor measure a partial discharge?

When a partial discharge event occurs, the coupling capacitor provides the devices under test (DUT) with a displacement current, which is measurable at the coupling devices (CPL). Such an approach provides additional information about the test discharge (PRPD) measurement. OMICRON ofers standard coupling capacitors from 12 kV up to 100 kV.

How do you measure a coupling capacitor discharge (PRPD)?

discharge (PRPD) measurement. OMICRON ofers standard coupling capacitors from 12 kV up to 100 kV. When using a coupling capacitor without an integrated measuring impedance, the low side of the coupling capacitor has to be connected to the input of the CPL measuring impedance (basic test setup with measurement on ground potential).

What are the advantages and disadvantages of Rogowski coil method?

The major advantage of using the Rogowski coil method is that it can capture more information about PD since its bandwidth is higher than the detectors used in the coupling method. The VLF testing kit’s portability and compactness make it possible to detect PD in long cable networks.

Can a VHF capacitive coupler Detect PD?

The VHF capacitive coupler technique was investigated by Tian et al. to detect and diagnose PD in cables, especially at cable joints. The PD location is detected using the time of arrival technique, and the suggested approach can capture PDs smaller than 3 pC.