Bil Basic Insulation Level. 1 for systems 1 kv< vm ≤ 245 kv (i) rated lightning impulse withstand level (liwl) (ii) 7.2 kv equipment basic insulation levels (bil) the differences in insulation levels, or withstand voltages, of differing types of electrical equipment can be quite puzzling.
Ch6 import
It was found that u10 for the bracket is 102 kv. Bil is an acronym for basic insulation level. Insulation levels recommended for a number of voltage classes are listed in table 1.
Ch6 import
Apparatus should be capable of withstanding test wave of basic insulation level or higher. Which means that the arrestor bracket must have a bil lower than that in order to absorb the surge. A correction coefficient is used to calibrate the adjustments to the specifications needed to make the components function correctly in thinner air. When lightning impulse over voltage appears in the system, it is discharged