ABB REX 521 Technical Reference Manual, Standard Configurations page 118

REX 521
)LJ  &RQQHFWLRQ RYHUYLHZ GLDJUDP RI WKH LQFRPLQJ IHHGHU
118
Protection Relay
Technical Reference Manual, Standard Configurations
TRIP circuit breaker
CLOSE circuit breaker
Io>>> TRIP to breaker on
HV side of transformer
Circuit-breaker failure
protection
OC blocking signal to
the HV relay (3I>> START)
Internal relay fault
OC blocking signal
from the outgoing feeders
to the 3I>>> stage
1MRS 751802-MUM