rated voltage of arrester

[dalas]

Hi.

i already have arrester with rated voltage is 144kv for 150kv system voltage,

how do you determine the rated voltage of an arrester for 275kv system voltage? type metal-oxide w/o gaps.

IEC60099-4, tabel 2 gives range of rated voltage 96-288(kv r.m.s) with steps of rated voltage 12kv. what does it mean?

thank you

 

[seymensaid]

Let me share my school knowledge with you.

A protection marge as 1.15 is selected. This is the ratio of a voltage level and the protection voltage level.
The voltage level is the strength level of the protected device.
The protection level is:

V2 = Va (arrester voltage) + Vb (connection voltage) + 2ml/v

This is just what I remember from my notes. That may give you an idea...