Schweitzer Engineering Laboratories SEL-421-4 - Figure 6.45 500 Kv Power System for Circuit Breaker Failure Scheme 2; Table 6.43 Secondary Quantities

6.162
SEL-421 Relay Instruction Manual Date Code 20171021
Protection Applications Examples
Circuit Breaker Failure Application Examples
Relay Configuration
Enable Scheme 2 circuit breaker failure protection for two circuit breakers.
EBFL1 := 2. Breaker 1 Failure Logic (N, 1, 2, Y1, Y2)
EBFL2 := 2. Breaker 2 Failure Logic (N, 1, 2, Y1, Y2)
Circuit Breaker 1 Failure Logic
Phase Current Level Detector
Set the phase fault current pickup greater than maximum load and less than the
fault current that flows through Circuit Breaker BK1 (I
S(BK1)
). Maximum load
current, I
S
, is 3.25 A secondary.
Figure 6.45 500 kV Power System for Circuit Breaker Failure Scheme 2
Ta b l e 6 .43 Se c o n d a r y Q u a n t i t i e s
Parameter Value
Line impedances
Z
1L1
Z
0L1
3.98 87.6° secondary
14.48 82.1° secondary
Source S impedances
Z
1S
= Z
0S
4.4 88° secondary
Source R impedances
Z
1R
= Z
0R
1.78 88° secondary
Nominal frequency (f
NOM
)60 Hz
Maximum operating current (I
load
) 3.25 A secondary
Line 1
Line 2
S (MOSCOW) R (PULLMAN)
BK1
BK2
BUS 1
IW
IX
SEL-421
BUS 2