Sel SEL-421 - DCUB Settings; GARD1 D: Guard-Present Delay

R.1.101
Date Code 20111215 Reference Manual SEL-421 Relay
Protection Functions
Directional Comparison Unblocking Scheme Logic
In addition, for a three-terminal line, program SELOGIC control equations
LOG1 and LOG2 as follows:
LOG1 := IN205 Channel 1 Loss-of-Guard
LOG2 := IN206 Channel 2 Loss-of-Guard
Relay control inputs IN205 or IN206 assert when the relay receives a loss-of-
guard signal from either of the two other terminals. When SEL
OGIC control
equation LOG1 (Channel 1 Loss-of-Guard) asserts, the relay asserts Relay
Word bit UBB1 (Block Permissive Trip on Receiver 1) and removes the
possibility that Relay Word bit PTRX1 (Permissive Trip on Receiver 1) will
assert. These two control inputs were chosen for this particular example. Use
control inputs that are appropriate for your application.
See Table 1.68 for the DCUB settings. The first portion of the settings (from
Z3RBD to PT1) are identical to the settings for the ECOMM := POTT
scheme; (see POTT Scheme Logic on page R.1.92).
Timer Setting
Recommendations
GARD1D: Guard-Present Delay
This timer determines the minimum time before the relay reinstates
permissive tripping following a loss-of-channel condition. Channel 1 and
Channel 2 logic use separate timers but have this same delay setting.
Table 1.68 DCUB Settings
Setting Description Range
Default
(5 A)
Z3RBD Zone 3 Reverse Block Time Delay
(cycles)
0.000–16000 5.000
EBLKD Echo Block Time Delay (cycles) 0.000–16000 10.000
ETDPU Echo Time Delay Pickup (cycles) 0.000–16000 2.000
EDURD Echo Duration Time Delay (cycles) 0.000–16000 4.000
EWFC Weak Infeed Trip Y, N, SP N
27PWI
a
a
Make setting when EWFC := SP
Weak Infeed Phase Undervoltage
Pickup (V)
1.0–200 47.0
27PPW
b
b
Make setting when EWFC := Y or SP
Weak Infeed Undervoltage Pickup
(V

)
0.1–300 80.0
59NW
b
Weak Infeed Zero-Sequence
Overvoltage Pickup (V)
0.1–200 5.0
PT1 General Permissive Trip Received SEL
OGIC Equation IN101 AND
PLT02
GARD1D Guard Present Security Delay (cycles) 0.000–16000 120.000
UBDURD DCUB Disabling Time Delay (cycles) 0.000–16000 180.000
UBEND DCUB Duration Time Delay (cycles) 0.000–16000 20.000
PT2
c
c
Make setting when ECOMM := DCUB2
Channel 2 Permissive Trip Received SELOGIC Equation NA
LOG1 Channel 1 Loss-of-Guard SEL
OGIC Equation NA
LOG2
c
Channel 2 Loss-of-Guard SELOGIC Equation NA