ABB Distribution Protection Unit 1500R/2000R
13-13
Applications Notes
9/99
website:www.abb.com/papd
Figure 13-18. Bus Fault: Bus and Feeder Relays OK
Condition 3: A Feeder DPU1500R/2000R Fails or Is Withdrawn from Its Case: Feeder Fault (see Figure 13-14)
The self-check alarm contact de-energizes the (74/Fn) relay. The (74/Fn) contact in the feeder trip circuit closes. The
PA relay is not energized, thereby enabling the 50-1 functions of the bus DPU1500R/2000R. The bus DPU1500R/
2000R’s 50-1 functions energize the Aux/B relay, which trips the feeder breaker with no reclosing.
Figure 13-19. Feeder Fault: Feeder 3 DPU1500R/2000(R) Has Failed
B
F3
DPU
B
74
F1
74
F2
74
F3
Aux
B
50-1
TRIP
50-1 TRIP
51&
50-2
TRIP
50-1 ENABLE
DPU
F3
Trip
74
F3
Aux
B
PA
In the absence of pickup from the feeder relays,
relays, the PA relay enables the 50-1 function
of the bus DPU1500R/2000R.
Bus DPU1500R/2000R trips bus
breaker based on 50-1 settings.
74/Fn contacts remain closed
unless a feeder relay fails.
Energized self-check alarm
keeps the 74/Fn relay open.
2
4
3
1
Fault
X
B
F3
DPU
B
74
F1
74
F2
74
F3
Aux
B
50-1
TRIP
50-1 TRIP
51&
50-2
TRIP
50-1 ENABLE
DPU
F3
Trip
74
F3
Aux
B
PA
In the absence of pickup from the feeder
relays, the PA relay enables the 50-1
function of the bus DPU1500R/2000R.
Closed Aux/B relay trips
the feeder breaker.
When feeder DPU1500R/2000R
fails, the self-check alarm
de-energizes the 74/Fn
relay and the contact closes.
2
4
5
1
Fault
X
Failed Feeder
Relay
Open 74/F3 prevents
tripping of bus breaker.
Bus DPU1500R/
backup to feeder
breaker failure
based on 50-2
and 51 settings.
3
6
Bus DPU1500R/2000R trips based on 50-1
settings and energizes Aux/B relay.
2000R provides