@article{oai:nagoya.repo.nii.ac.jp:00012642,
 author = {Mansour, Diaa-Eldin A and Nishizawa, Kanako and Kojima, Hiroki and Hayakawa, Naoki and Endo, Fumihiro and Okubo, Hitoshi},
 issue = {1},
 journal = {Dielectrics and Electrical Insulation, IEEE Transactions on},
 month = {Feb},
 note = {The partial discharge (PD) measurements are considered as the most important tool  for condition monitoring of Gas Insulated Switchgears (GISs). However, if spacer  surface is involved in PD activity, charge accumulation process greatly affects the time  transition of PD characteristics. This paper investigates this effect considering the  defect types of delamination at the electrode/spacer interface and metallic particles  adhered to the spacer surface as the most serious defects that can lead to major failure.  Two different electrode configurations were built to simulate the two defect types. The  PD characteristics were measured and analyzed from immediately after voltage  application up to several minutes where steady state characteristics have been obtained.  As a result, it was found that the generation rate of PD pulses changed considerably  with time for both defect types. This tendency of PD characteristics has been discussed  considering the effect of charge accumulation. Comparing these effects for negative  and positive PD enabled to clarify the similarities and differences in the charge  accumulation effect for both defect types which can contribute to the defect type  identification in GIS. It was found that the effects of charge accumulation on the  electric field strength for the delamination defect case as well as on the ionization  volume for the metallic particle case were the responsible parameters for the different  PD tendencies.},
 pages = {247--255},
 title = {Charge accumulation effects on time transition of partial discharge activity at GIS spacer defects},
 volume = {17},
 year = {2010}
}