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6.161
Date Code 20171021
Instruction Manual
SEL-421 Relay
Protection Applications Examples
Circuit Breaker Failure Application Examples
Circuit Breaker Failure Protection—Example 2
Use the SEL-421 to provide circuit breaker failure protection for both circuit
breakers in breaker-and-a-half schemes. This application example explains set-
ting the relay for Circuit Breaker BK1 (see
). You can apply these
same settings for Circuit Breaker BK2. You can apply circuit breaker failure
Scheme 2 protection for single-pole trip circuit breakers. Scheme 2 provides sep-
arate timers for multiphase faults (BFPU1) and single-phase faults (SPBFPU1).
For more information on Scheme 2 circuit breaker failure protection, see
to Interrupt Fault Current: Scheme 2 on page 5.148
NOTE:
This application example is
for two circuit breakers. Apply the
same settings for Circuit Breaker BK2
as for Circuit Breaker BK1. For Circuit
Breaker BK2, substitute 2 for 1 in the
following settings.
This example uses a 500 kV power system with single-pole tripping enabled (see
provides the power system parameters.
Breaker 1 Failure Logic (Group)
50FP1
Phase Fault Current Pickup—BK1 (0.50–50 A secondary)
5.94
BFPU1
Breaker Failure Time Delay—BK1 (0.000–6000 cycles)
10.000
RTPU1
Retrip Time Delay—BK1 (0.000–6000 cycles)
4.000
BFI3PI
Three-Pole Breaker Failure Initiate—BK1 (SEL
OGIC
Equation)
3PT
BFIA1
A-Phase Breaker Failure Initiate—BK1 (SEL
OGIC
Equation)
NA
BFIB1
B-Phase Breaker Failure Initiate—BK1 (SEL
OGIC
Equation)
NA
BFIC1
C-Phase Breaker Failure Initiate—BK1 (SEL
OGIC
Equation)
NA
BFIDO1
Breaker Fail Initiate Dropout Delay—BK1 (0.000–1000 cycles)
0.000
BFISP1
Breaker Fail Initiate Seal-In Delay—BK1 (0.000–1000 cycles)
0.000
ENCBF1
No Current/Residual Current Logic—BK1 (Y, N)
Y
50RP1
Residual Current Pickup—BK1 (0.25–50 A secondary)
0.74
NPU1
No Current Breaker Failure Delay—BK1 (0.000–6000 cycles)
12.000
BFIN1
No Current Breaker Failure Initiate—BK1 (SEL
OGIC
Equation)
NA
ELCBF1
Load Current Breaker Failure Logic—BK1 (Y, N)
N
EFOBF1
Flashover Breaker Failure Logic—BK1 (Y, N)
N
BFTR1
Breaker Failure Trip—BK1 (SEL
OGIC
Equation)
FBF1 OR
NBF1
BFULTR1
Breaker Failure Unlatch Trip—BK1 (SEL
OGIC
Equation)
IN104
Main Board (Outputs)
OUT101
3PT
OUT103
RT1
OUT107
BFTRIP1
Table 6.42
Settings for Circuit Breaker Failure Example 1 (Sheet 2 of 2)
Setting
Prompt
Entry
Содержание SEL-421-4
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