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6.147
Date Code 20171021
Instruction Manual
SEL-421 Relay
Protection Applications Examples
Autoreclose and Synchronism-Check Example
Voltage Elements
Enable the voltage check elements.
EVCK :=
Y
.
Reclosing Voltage Check (Y, N)
Set the dead line voltage threshold equal to 15 V secondary.
27LP :=
15.0
.
Dead Line Voltage (1.0–200 V secondary)
Set the live line voltage threshold equal to 50 V secondary.
59LP :=
50.0
.
Live Line Voltage (1.0–200 V secondary)
Set the dead bus voltage threshold for Circuit Breakers 1 and 2 equal to 15 volts
secondary.
27BK1P :=
15.0
.
Breaker 1 Dead Busbar Voltage (1.0–200 V secondary)
27BK2P :=
15.0
.
Breaker 2 Dead Busbar Voltage (1.0–200 V secondary)
Set the live bus voltage threshold for Circuit Breakers 1 and 2 equal to 50 V sec-
ondary.
59BK1P :=
50.0
.
Breaker 1 Live Busbar Voltage (1.0–200 V secondary)
59BK2P :=
50.0
.
Breaker 2 Live Busbar Voltage (1.0–200 V secondary)
Trip Logic
If you want Circuit Breaker 2 to always three-pole trip, except when Circuit
Breaker 2 is the leader, program SEL
OGIC
control equation E3PT2 as follows:
E3PT2 :=
NOT LEADBK2
.
Breaker 2 3PT (SEL
OGIC
Equation)
Synchronism-Check Application
Reclose Circuit Breaker 1 following a three-pole trip if the line is dead and Bus 1
is hot. Reclose Circuit Breaker 2 following a three-pole trip if a synchronism
check across the hot line to Bus 2 is successful or Circuit Breaker 1 is out of ser-
vice and the line is dead and Bus 2 is hot.
Figure 6.39
Potential Sources
BUS 1
VAZ
VY
(Bus Potential)
(Bus Potential)
(Line Potential)
Follower
Line Disconnect
SEL-421 Relay
Leader
VBZ
from BUS 2
CB1
CB2
3
1
1
Summary of Contents for SEL-421-4
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