5.19
Date Code 20060320
Instruction Manual
SEL-311C Relay
Trip and Target Logic
Directional Comparison Unblocking Logic
Directional Comparison Unblocking Logic
Enable the directional comparison unblocking (DCUB) logic by setting
ECOMM = DCUB1 or ECOMM = DCUB2. The DCUB logic in
is an extension of the POTT logic in
. Thus, the relay requires
all
the POTT settings and logic,
plus
settings and logic exclusive to DCUB. The
difference between setting choices DCUB1 and DCUB2 is:
DCUB1
directional comparison unblocking scheme for two-terminal line
(communications from
one
remote terminal)
DCUB2
directional comparison unblocking scheme for three-terminal line
(communications from
two
remote terminals)
The DCUB logic in
takes in the loss-of-guard and permissive trip
outputs from the communications receivers (see
and
)
and makes permissive (PTRX1/PTRX2) and unblocking block (UBB1/UBB2)
logic output decisions.
Use Existing
SEL-321 DCUB
Application Guide for
the SEL-311C
Use the existing SEL-321 DCUB application guide (AG96-19) to help set up
the SEL-311C in a DCUB scheme (see
Logic-General Overview on page 5.10
for more setting comparison
information on the SEL-321/SEL-311C relays).
External Inputs
Optoisolated Inputs on page 7.3
for more information on optoisolated
inputs.
PT1, PT2—Received Permissive Trip Signal(s)
In two-terminal line DCUB applications (setting ECOMM = DCUB1), a
permissive trip signal is received from
one
remote terminal. One optoisolated
input on the SEL-311C (e.g., input
IN104
) is driven by a communications
equipment receiver output (see
). Make SEL
OGIC
control equation
setting PT1:
PT1 =
IN104
(two-terminal line application)
In three-terminal line DCUB applications (setting ECOMM = DCUB2),
permissive trip signals are received from
two
remote terminals. Two
optoisolated inputs on the SEL-311C (e.g., inputs
IN104
and
IN106
) are driven
by communications equipment receiver outputs (see
). Make
SEL
OGIC
control equation settings PT1 and PT2 as follows:
PT1 =
IN104
(three-terminal line application)
PT2 =
IN106
SEL
OGIC
control equation settings PT1 and PT2 are routed into the DCUB
for “unblocking block” and “permissive trip receive”
logic decisions.
As explained in
Permissive Overreaching Transfer Trip Logic on page 5.13
the SEL
OGIC
control equation settings PT1 and PT2 in
are routed
in various combinations to control Relay Word bit PT, depending on enable
setting ECOMM = DCUB1 or DCUB2. Relay Word bit PT is then an input
into the POTT logic in
(for echo keying).
Summary of Contents for SEL-311C
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