ABB DPU 1500R Instruction Book page 169

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Application Note AN-22
The Distribution Protection Unit 1500R/2000R (DPU1500R/2000R) has Multiple Device Trip (MDT) mode capability.
When you enable its MDT mode, a DPU1500R/2000R on a bus breaker can be programmed to provide primary
protection for the bus and backup protection to feeder breakers. If the relay protecting the feeder fails, the bus
breaker DPU1500R/2000R provides isolated backup tripping to the faulted feeder breaker without tripping the bus
breaker. Continuity of service will be maintained on all of the unfaulted feeders.
Component Requirements
The DPU1500R/2000R includes the logic and timing elements and the programming flexibility to allow such backup
protection with few additional devices:
• DPU1500R/2000R for bus breaker (DPU/B)
• DPU1500R/2000R for each feeder breaker (DPU/Fn*)
• 1 Pickup Auxiliary relay (PA)
• 1 Auxiliary Tripping relay on the bus (Aux/B)
• Auxiliary Self-Check Failure relay (74/Fn*) for each feeder breaker
n* = Number of feeder
74
F1
One per Breaker
Applications Notes
Bus Breaker Backup to Feeder Breaker
PUA PUA PUA
F1 F2 F3
PA
DPU
Aux
Fail
F1
B
F1
74
F1
Trip
F1
Figure 13-8. Multiple Device Trip Mode Schematic
ABB Distribution Protection Unit 1500R/2000R
PA
50-1 ENABLE
50-1 TRIP
DPU
B
50-1
TRIP
51& 74
F1
50-2
74
TRIP
F2
74
F3
B
DPU
Aux
F2
B
74
F2
Trip
F2
website:www.abb.com/papd
Aux
B
DPU
Aux
F3
B
74
F3
Trip
F3
13-7