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5.10
SEL-351-5, -6, -7 Relay
Instruction Manual
Date Code 20070117
Trip and Target Logic
Communications-Assisted Trip Logic—General Overview
Communications-Assisted Trip Logic—General
Overview
The SEL-351 includes communications-assisted tripping schemes that
provide unit-protection for transmission lines with the help of
communications. No external coordination devices are required.
Figure 5.4
Communications-Assisted Tripping Scheme
and the top half of
.
The six available tripping schemes are:
➤
Direct Transfer Trip (DTT)
➤
Direct Underreaching Transfer Trip (DUTT)
➤
Permissive Overreaching Transfer Trip (POTT)
➤
Permissive Underreaching Transfer Trip (PUTT)
➤
Directional Comparison Unblocking (DCUB)
➤
Directional Comparison Blocking (DCB)
Enable Setting
ECOMM
The POTT, PUTT, DCUB, and DCB tripping schemes are enabled with enable
setting ECOMM. Setting choices are:
ECOMM =
N
[no communications-assisted trip scheme enabled]
ECOMM =
POTT
[POTT or PUTT scheme]
ECOMM =
DCUB1
[DCUB scheme for two-terminal line (communications
from one remote terminal)]
ECOMM =
DCUB2
[DCUB scheme for three-terminal line (communications
from
two
remote terminals)]
ECOMM =
DCB
[DCB scheme]
These tripping schemes can all work in two-terminal or three-terminal line
applications. The DCUB scheme requires separate settings choices for these
applications (ECOMM = DCUB1 or DCUB2) because of unique DCUB logic
considerations.
Level 3 (1)
Level 1 (1)
Level 2 (1)
Level 1 (2)
Level 3 (2)
Level 2 (2)
SEL-351
SEL-351
Bus 1
Bus 2
Comm.
Equip
Comm.
Equip
TX
TX
RX
RX
Transmission Line
52
1
52
2
Summary of Contents for SEL-351-5
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