Schweitzer Engineering Laboratories SEL-351-5, Instruction Manual

Page: 223 / 706

5.21
Date Code 20070117
Instruction Manual SEL-351-5, -6, -7 Relay
Trip and Target Logic
Directional Comparison Unblocking (DCUB) Logic
LOG1, LOG2—Loss-of-Guard Signal(s)
In two-terminal line DCUB applications (setting ECOMM = DCUB1), a loss-
of-guard signal is received from
one remote terminal. One optoisolated input
on the SEL-351 (e.g., input
IN105
) is driven by a communications equipment
receiver output (see Figure 5.12 ). Make SEL
OGIC
control equation setting
LOG1:
LOG1 = IN105 (two-terminal line application)
In three-terminal line DCUB applications (setting ECOMM = DCUB2), loss-
of-guard signals are received from
two remote terminals. Two optoisolated
inputs on the SEL-351 (e.g., input IN105 and IN207 ) are driven by
communications equipment receiver outputs (see Figure 5.13 ). Make
SEL
OGIC
control equation settings LOG1 and LOG2 as follows:
LOG1 = IN105 (three-terminal line application)
LOG2 = IN207
SEL
OGIC
control equation settings LOG1 and LOG2 are routed into the
DCUB logic in Figure 5.10 for “unblocking block” and “permissive trip
receive” logic decisions.
Timer Settings
See Section 9: Setting the Relay for setting ranges.
GARD1D—Guard-Present Delay
Sets minimum time requirement for reinstating permissive tripping following
a loss-of-channel condition—typically set at 10 cycles. Channel 1 and 2 logic
use separate timers but have this same delay setting.
UBDURD—DCUB Disable Delay
Prevents tripping by POTT logic after a settable time following a loss-of-
channel condition—typically set at 9 cycles (150 ms). Channel 1 and 2 logic
use separate timers but have this same delay setting.
UBEND—DCUB Duration Delay
Sets minimum time required to declare a loss-of-channel condition—typically
set at 0.5 cycles. Channel 1 and 2 logic use separate timers but have this same
delay setting.
Logic Outputs
The following logic outputs can be tested by assigning them to output
contacts. See
Output Contacts on page 7.32 for more information on output
contacts.
UBB1, UBB2—Unblocking Block Output(s)
In two-terminal line DCUB applications (setting ECOMM = DCUB1), UBB1
disables tripping if the loss-of-channel condition continues for longer than
time UBDURD.
In three-terminal line DCUB applications (setting ECOMM = DCUB2),
UBB1 or UBB2 disable tripping if the loss-of-channel condition (for the
respective Channel 1 or 2) continues for longer than time UBDURD.