ABB Distribution Protection Unit 1500R/2000R
13-12
Applications Notes
9/99
website:www.abb.com/papd
Sample Operation
Condition 1. Feeder and Bus DPU1500R/2000R OK: Feeder Fault (see Figure 13-17).
The pickup alarm (PUA) picks up the pickup auxiliary relay (PA). The PA contact disables the 50-1 functions of the
bus DPU1500R/2000R. The feeder relay trips for the fault and recloses after the set open interval time expires.
All auxiliary self-check relays (74/Fn) are picked up, blocking the bus DPU1500R/2000R from tripping the feeder
breaker.
Figure 13-17. Feeder Fault: Bus and Feeder Relays OK
Condition 2: Feeder and Bus DPU1500R/2000R OK: Bus Fault (see Figure 13-18).
The pickup auxiliary relay (PA) is not energized, and therefore the 50-1 function of the bus DPU1500R/2000R is
enabled. The 50-1 function trips the bus breaker after 0.05 seconds through the closed contacts of the energized (74/
Fn) relays.
B
F3
DPU
B
74
F1
74
F2
74
F3
Aux
B
50-1
TRIP
50-1 TRIP
51&
50-2
TRIP
50-1 DISABLED
DPU
F3
Trip
74
F3
Aux
B
PA
In the presence of pickup from feeder
relay #3, the PA relay disables the 50-1
function of the bus DPU1500R/2000R.
Bus DPU1500R/2000R provides bus
protection and backup F3 breaker failure
based on 50-2 and 51 settings.
Pickup alarm (PUA) for
feeder relay 3 closes,
causing PA relay to
open its contact.
Sensing the fault, the
feeder DPU1500R/2000R
trips the breaker.
2
4
1
3
Fault
X
PA
PUA
F1
PUA
F2
PUA
F3