Teleprotection
GARD 8000 SYS RFL Electronics
March 1, 2006 9-3 973.334.3100
9.2.2 DIRECT TRANSFER TRIP
A direct transfer trip system is one in which the teleprotection device is solely responsible for tripping
of the remote breaker. This type of system is generally used for tripping remote circuit breakers, for
transformer faults, shunt reactor protection and breaker failure applications. DTT schemes typically
require trip times around 12ms, however, the trip times are not quite as critical as with PTT systems,
since DTT systems are typically backup protection. Because the teleprotection unit is solely
responsible for tripping, without supervision from the local relay, security and dependability is of the
utmost importance.
Figure 9-3. Direct Transfer Trip