Protection Engineering Basics and Schemes Protection Engineering | Page 78

Here i mention two output because my VT is multicore,
each core with dual class of metering and protection, this
is advancement in technology.
VT metering classes are 0.1, 0.2, 0.5, 1 and 3 and
protection classes are 3p and 6p, here i adopted 0.2 for
metering and 3p for protection purpose. Burdens are
25VA in both cases of metering and protection. We
protected Out pt by fuses (HRC) from Primary side and
Miniature circuit Breakers(MCBs) from secondary side as
per recommended practices.
we have multifunction relays SEL-487V and C-70 here for
under/over Voltage (27/59), instantaneous/Inverse Over
Current relay(50/51), instantaneous/Inverse Over
Current earth fault relay(50/51N), non-directional
Overcurrent relay(59ND),Directional Overcurrent
Relay(67), Inter tripping or circuit breaker failure
relay(CBF), Trip circuit supervision Relay(TCS) , negative
sequence overcurrent relay (46). in C-70 you have
thermal overload protection function also 49.
pg. 78