Basic impulse level (IEC)
Basic impulse level (IEC)
(OP)
I have a question regarding rated impulse test voltage (BIL) selection for an MV switchgear (IEC):
-operatin voltage 10kv 50hz
-rated insulation: 17.5kv
-rated Power-Frequency Withstand voltage (1min)38kv.
Per IEC for this case, both 75kv and 95kv are possible for rated Impulse Test Voltage (BIL).
please advise how to decide about sufficieny of 75kv, and if there is any calculation, example..
thanks.
-operatin voltage 10kv 50hz
-rated insulation: 17.5kv
-rated Power-Frequency Withstand voltage (1min)38kv.
Per IEC for this case, both 75kv and 95kv are possible for rated Impulse Test Voltage (BIL).
please advise how to decide about sufficieny of 75kv, and if there is any calculation, example..
thanks.






RE: Basic impulse level (IEC)
For explanation see IEC 600071-2 art.5.1.2 Standard lightning impulse withstand :
a)for equipment protected by close surge arresters, the low values of lighting impulse withstand level are applicable.....
b)for equipment not protected by surge arresters (or not effectively protected), only the
higher values of lightning impulse withstand voltages shall be used.....
RE: Basic impulse level (IEC)
Can I understand that if I have surge arrestors on transformer side and on MV switchgear (on main incomer), I do not need to use the higher value 95kv
RE: Basic impulse level (IEC)
http://blog.schneider-electric.com/power-managemen...
RE: Basic impulse level (IEC)
For the system connected with lot of exposed conductors, higher LI voltage is preferred.