Re: Basic Impulse Level(BIL)


First of all, BIL is Basic Insulation Level and NOT basic impulse level, as mentioned by you incorrectly. The BIL includes the power frequency overvoltage withstand capacity and the impulse (both Lightning Impulse and
p the Switching Impulse) withstand capacity.

Sub-station clearances are decided on the BIL, as any insulation or dielectric is stressed by these voltages.