ABB Distribution Protection Unit 1500R
1-26
Protective Functions
9/99
website:www.abb.com/papd
The internal DPU1500R logic only checks the status of the 79S logical input when it detects that the circuit
breaker has opened. Once it has determined that the 79S is active, it will initiate the single shot reclose. It
doesn’t matter if the 79S is toggled or held active.
If the single shot recloser is in the middle of the open time or reset time and the recloser is dissabled via the
43A logical input, the recloser will stop operation. When 43A is returned to the active state the recloser will be
reset.
Multi-Shot Reclose Logical Input 79M (O->I)
The 79M logical input is used to initiate multiple shots of reclosing when the circuit breaker is opened by an external
source. Logical input 79M must be mapped to a physical input contact for activation by an external device (see
Programmable Inputs Section). The 43A (recloser enable) logical input must also be active for the 79M function to
operate. If 43A is not mapped to a physical input it defaults to enable. The 79M operates as follows:
If the breaker is opened by an external source and the 79M logical input is active, the circuit breaker will close in the 79-
1 open time. If the circuit breaker is opened again by an external source and the reset time has not expired, the
recloser will step to 79-2 and the circuit breaker will close (or lockout depending upon the 79-2 programming) in 79-2
time. If the breaker continues to open before the reset time expires, the recloser will continue to increment steps until
it reaches the step that locks out. At this point no further reclosing will take place and the circuit breaker must be
closed manually.
If the breaker is opened by an external source and the 79M logical input is not active but is made active after the circuit
breaker is opened, the circuit breaker will close in the 79-1 open time. If the circuit breaker is opened again by an
external source and the reset time has not expired, the recloser will step to 79-2 and the circuit breaker will close (or
lockout depending upon the 79-2 programming) in 79-2 time. If the breaker continues to open before the reset time
expires, the recloser will continue to increment steps until it reaches the step that locks out. At this point no further
reclosing will take place and the circuit breaker must be closed manually.
The 79M function can be made active or inactive by the mapping a User Logical Output (ULO) to the 79M
logical input through the feedback logic (see Programmable Logic Section).
The internal DPU1500R logic only checks the status of the 79M logical input when it detects that the circuit
breaker has opened. Once it has determined that the 79M is active, it will initiate the reclose. It doesn’t matter
if the 79M is toggled or held active.
If the multi-shot recloser is in the middle of a sequence and the 43A logical input is made inactive, the recloser
will stop operation. When 43A is returned to the active state the recloser will be reset and at step 79-1.
Voltage Block 79V (O->IU<)
The 79V Voltage Block function blocks reclosing when one or more of the input voltages is below the 79V voltage
setting. When the input voltage is restored within the 79V time delay setting, the recloser operation is unblocked and
the “open time” will begin. If the voltage is
not restored within the 79V time delay
setting, the recloser will proceed to lockout.
The 79V time delay can be set to count in
seconds or minutes. The setting, “79V Time
Mode”, is made in the Configurations settings
(see Section 2). This function is useful in
preventing a feeder breaker closure when the
bus voltage is lost or below normal. This
reduces inrush currents when the voltage to
the bus is eventually restored. The settings
for the 79V function are listed in Table 1-14.
The 79V element is disabled in the factory
default settings.
Note: If the voltage is lost or falls below the 79V voltage setting during the open
time interval, the open timer will halt. If the voltage is restored before the
79V time delay expires, the open timer will again run. If the voltage is not
restored and the 79V time delay expires, the recloser will proceed to
lockout.
Table 1-14. 79V (O->IU<) Characteristics
79V Parameter
Range/Curve
Increment
Voltage
10 to 200 VAC
1 volt
Time Delay
4.0 to 240 seconds
1 sec. (79V time mode: seconds)
Time Delay
1.0 to 60 minutes
1 min. (79V time mode: minutes)
