Timer Settings - Schweitzer Engineering Laboratories SEL-311L Instruction Manual

As explained in the preceding POTT subsection, the SEL
PT2 in Figure 5.7 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 Figure 5.8 (for echo keying).
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-311L Relay (e.g., input
IN105) is driven by a communications equipment receiver output (see Figure 5.14). Make
SEL control equation setting LOG1:
OGIC
LOG1 = IN105
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-311L Relay (e.g.,
input IN105 and IN103) are driven by communications equipment receiver outputs (see
Figure 5.15). Make SEL
LOG1 = IN105
LOG2 = IN103
SEL control equation settings LOG1 and LOG2 are routed into the DCUB logic in
OGIC
Figure 5.12 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.
Date Code 20010625
(two-terminal line application)
control equation settings LOG1 and LOG2 as follows:
OGIC
(three-terminal line application)
Trip and Target Logic
SEL-311L Instruction Manual
control equation settings PT1 and
OGIC
5-25