Schweitzer Engineering Laboratories, Inc.
SEL-487B Data Sheet
9
Figure 16
Single SEL-487B Protecting Double Bus Sections With Bus Tie Breaker
Figure 17
Two Single SEL-487B Relays Protecting the Two Busbars in a Breaker-and-a-Half Busbar Configuration
For stations with 10 to 21 terminals (Figure 18), use
three separate SEL-487B relays and wire analog current
inputs from A-, B-, and C-phases separately into each
relay. This way, each of the 21 analog current inputs in
each relay measures only one phase, with six dedicated
zones of protection available. Each relay operates
independently; the only communication among relays is
M
IRRORED
B
ITS
®
communication and IRIG-B. In this
application, operators have complete flexibility because
they can close any disconnect at any time without
compromising the busbar protection. This is possible
Zone 1
Zone 2
52
52
52
52
52
3
3
3
3
3
3
400/5
FDR_1
FDR_2
FDR_3
FDR_4
800/5
2000/5
2000/5
4000/5
3000/5
SEL-487B
Bus 2
Bus 1
3
3
3
3
3
3
52
52
52
52
52
52
52
52
52
SEL-487B
SEL-487B
•
•
•
•
•
•
4000/5
2000/5
FDR_1
FDR_8
FDR_2
FDR_9
FDR_7
FDR_14
2000/5
1000/5
400/5
200/5
