3 ph system has transformer (
13.8k(v)/(0.4)kv
),
3500KVA
Calculate the faul impedance (
Znet
, pu) of a symmetrical fault current at
LV
side if the operating time of normal IDMT relay is
1000ms
, the ratio of
CT
is
(900)/(5)
and the pick up current is
200%
with TMS 0.3