The trip signal from local criterion will ensure the fault at the remote end and release the
trip signal to the local side circuit breaker. The local criterion must detect the abnormal
conditions and permit the CR signal to trip the circuit breaker.
DTT scheme comprises following local criteria checks as shown in Figure
381.
C
B
T
r
i
p
o
u
t
p
u
t
Low impedance protection
Sudden change in current
variation
Zero sequence overcurrent
protection
Negative sequence overcurrent
protection
Zero sequence overvoltage
protection
Negative sequence overvoltage
protection
Compensated over and
undervoltage protection
Three phase undercurrent
Three phase overcurrent
Backup trip of breaker failure
protection
OR
Low active power and power
factor protection
A
n
a
l
o
g
i
n
p
u
t
V3P
I3P
ANSI09000773-1-en.vsd
LocalCheck
CR!
CR2
CR!
CR2
Impedance protection
Breaker Failure
LCCRPTRC (94)
CarrierReceiveLogic
ANSI09000773 V1 EN
Figure 381: DTT scheme
16.8.2 Setting guidelines
Setting guidelines for Direct transfer trip functions are outlined in the following sections.
Section 16 1MRK 506 369-UUS -
Scheme communication
776 Line distance protection REL670 2.2 ANSI
Application manual
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