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Hi All, While nominated for carrying out insulation coordination study for EHV system using PSCAD, I came to a point for transmission line transient that takes me back to some undergraduate courses, the point is the reflected wave. I understand that there is a wave which is travelling along a...

All, Thanks for you helpful reply, Cuky2000, may I know the reference for the selection of 1/2 or 2/3 of phase-to-ground clearance as a check between insulators shanks / heads?

Hi all, when designing an EHV SS, it was noticed that the SA phase-to-ground clearance is interfering with the SF6 Air Bushing insulator (not grounded structure, i understand that there shall be some voltage in between zero and the HV Phase voltage somewhere on the bushing surface as it is...

Hi all, In a 380 kV System, After running a study for insulation coordination with PSCAD, with a lightning impulse of 1.7/77 us, the resultant voltage on bushing was showing oscillatory response with a peak of 846 kV and 2.5/103 us overall characteristic(the oscillation isn't reaching the...

It is well known that no switching study is required for systems less than 300 kV, my question is why no BSL nor switching study is required for such voltage level?

I understand that the fence continuity must be sustained for personnel safety & fault identification in case of line dropped on SS fence!

I guess it is the cooling type : ANF = Air Natural / Forced i.e. via shaft coupled fan!! I am not specialized in such sized motors, I just guess!

Simply yes, since the corona ring is live at system phase voltage,Phase-to-phase clearance shall be considered out of both rings edge.

Hi Jan63, System stability shall be checked against the new capcaity / load. The economic operation of the existing line ( Kelvin rule ) may lead to a unoptimized conductor for the new current rating, although the conductor can carry ( if the current rating is beyond the capcaity e.g. 4*896 =...

Alan, This is correct, TL must survive fogs, this is correct for the existing line " erected about 20 years ago ", but,when the modification took place, the flashover occured on the two adjacent towers only, this flashover took place for about 4 days ,at 6 a.m. everyday, the flashover was...

no capacitors on this SS, or on 380 kV network completely, at 6 a.m., the humidity is very high,

Hi all, It has been reported to our department that a new substation has supply by in-out arrangement from an existing double circuit 380kV OHTL, experiences frequent FLASHOVER on the two suspension towers adjacent to the tapping point, the flashovers occured almost at same time daily it is...