Stacking MV Insulators

[bceng87SS1517]

Can you stack medium voltage bus support/standoff insulators and get the same voltage rating at the overall height compared to a single insulator at that height. i.e. if I use two 6" insulators instead of a single 12" insulator should the clearance be "derated" at all? Would the BIL be the same?

 

[cuky2000]

What is the target BIL that are you looking for?

The BIL of the assembly of 2 insulators depends on the staking method and the type of insulator. Based on the curve below, there is a good hope that 2-6" insulators could achieve 150 kV BIL that is the rating of one typical 12" insulator.
However, without an actual impulse test, there will be natural uncertainties to warranty the target BIL value.

See the graph below for reference