Schweitzer Engineering Laboratories SEL-351-5, Instruction Manual

Page: 231 / 706

5.29
Date Code 20070117
Instruction Manual SEL-351-5, -6, -7 Relay
Trip and Target Logic
Directional Comparison Blocking (DCB) Logic
Depending on the installation, perhaps one output contact (e.g., OUT106 =
STOP) can be connected in parallel to both
STOP
inputs on the communication
equipment in Figure 5.16 . Then output contact
OUT208
can be used for another
function.
Figure 5.16 also shows communication equipment
RX
(receive) output
contacts from each remote terminal connected to separate inputs
IN104
and
IN106
on the SEL-351. The inputs operate as block trip receive inputs for the
two remote terminals and are used in the SEL
OGIC
control equation setting:
BT = IN104 + IN106
Depending on the installation, perhaps one input (e.g., IN104 ) can be connected
in parallel to both communication equipment
RX
(receive) output contacts in
Figure 5.16 . Then setting BT would be programmed as:
BT =
IN104
and input
IN106
can be used for another function.
In Figure 5.15 and Figure 5.16 , the carrier scheme cutout switch contact
(85CO) should be closed when the communications equipment is taken out of
service so that the
BT
input of the relay remains asserted. An alternative to
asserting the
BT
input is to change to a setting group where the DCB logic is
not enabled.
Figure 5.15 Connections to Communications Equipment for a Two-Terminal
Line DCB Scheme
(—)
OUT105 = DSTRT + NSTRT
OUT106 = STOP
(+)
OUT106
(TX) START STOP
OUT105
(TX) RX
85CO
SEL-351
(Partial)
IN104
To / From
Remote
Terminal
BT = IN104
RX
TX