Modulation of partial discharge activity in GIS insulators by X-ray irradiation

Continuous and pulsed X-ray induced partial discharges: similarities and differences

“…Conventional PD tests often use an AC overvoltage to check partial discharge occurrences in voids. Occasionally, the AC voltage stress may not be enough to activate partial discharges but, on the other hand, may result in irreversible damage by initiating electrical trees from other stressed enhancing defects, such as metallic particles and protrusions on electrodes [6][7][8].…”

Investigating the inception mechanism of pulsed x-ray triggered partial discharges by time resolved measurements

“…The measured phase resolved PD patterns did not differ from the naturally triggered ones [13]. The main difference of PXIPD to the XIPD shown in [6][7][8][9][10] is that the X-ray pulse supplies only the start electrons for the first PD, the subsequent PDs are not supported by the X-ray beam.…”

“…First reports on X-ray application to PD detection were published in the 60`s [5], but a more comprehensive attempt was made towards the end of the 80`s at Ontario Hydro [6][7][8]. Here, continuous X-ray irradiation was used and the measurements were performed on real GIS insulators with defined artificial defects.…”

“…However the applied X-ray beam effected directly the height/phase distributions and patterns. They were tightened and at overrated X-ray doses PDs were suppressed completely [7][8]. It was concluded that the Xray beam ionized the gas in the cavity to the point of conductivity, thus shielding the electric field.…”

Investigation of partial discharge characteristics induced by X‐ray irradiation in artificial cavity in epoxy resin

“…Thus, experiments were conducted to promote PD by X-ray irradiation of void defects in the epoxy spacers of GIS and other solid insulators [7][8][9]. These studies showed that the PD inception voltage (PDIV) decreased due to X-ray irradiation; however, the underlying mechanisms were discussed only qualitatively, in terms of the supply of initial electrons to voids, and no quantitative estimation was made.…”