BIL Question.
BIL Question.
(OP)
Hi all:
Im new in foro and i have some query about BIL.
Why BIL are derrating in high altitude (over 1000 masl)?
I have the impression that the distances are increasing at a higher altitude and not "material quality" (eg porcelain insulator).
I hope we can discuss and present different points of view.
Im new in foro and i have some query about BIL.
Why BIL are derrating in high altitude (over 1000 masl)?
I have the impression that the distances are increasing at a higher altitude and not "material quality" (eg porcelain insulator).
I hope we can discuss and present different points of view.






RE: BIL Question.
For example, at 2000 masl, air pressure is about 0.8 atm (608 torr). According to this chart breakdown voltage across a 0.1" air gap falls by about 10kV.
RE: BIL Question.
Now, the Pashen´s curve exposes what im saying (distance need increasing over 1000 masl), but i understand for BIL which is the basic insulation level for one material, for example:
For epoxy dry tranformer, IEC 60076-11 indicate for transformer for use at high altitudes (12.2), shall be increased by 1% for each 100 m above 1000 m, but, the material are the same (have the same material at 1000 m). No indicate derating the BIL of material (epoxy).
Someone else has another point of view?
RE: BIL Question.
So a device with a BIL rating of 550 kV would have to be de-rated to 495 kV at 2000 masl (10% derating = 1% per 100m above 1000m).