Chapter 6. Description of Operation of Protection Subsystem
6-25
M7IRDA2003I
7IRD-A/J/M: Distribution Protection & Control Terminal
© ZIV APLICACIONES Y TECNOLOGÍA, S.L.U. 2020
6.9
Breaker Monitoring
7IRD
terminal units record the interrupting current for each trip of the associated breaker and
accumulate it as amperes squared (
I
2
). This number is proportional to the accumulated power
actually interrupted by the breaker.
When a trip is initiated, the largest of the three phase primary currents is recorded and then
stored as
I
2
. The current measurement period is between trip initiation and breaker opening.
When the breaker is opened manually, either through the terminal unit or by external means,
the value accumulated is equivalent to the square of the time Overcurrent pickup setting.
Once the value established for the Alarm Level of
I
2
is reached, the function activates the
I
2
Alarm
Level signal that can be used to activate a programmable Auxiliary Contact Output. When
activated, this output is captured by the sequence of events recorder.
This function has two settings:
-
I
2
Alarm Level.
-
I
2
Cumulative Present Value.
The
Cumulative Present Value
is updated each time a breaker opening operation takes place.
It represents a base to which successive interruption values are added. This setting can be
modified by the user to set an initial value into a newly installed terminal unit to match the
history of an existing breaker. The value may also be reset to zero after major breaker
maintenance has been completed.
6.9.1
Excessive Number of Trips
The
Excessive Number of Trips
function is intended to interrupt an uncontrolled sequence of
openings and closings that could damage the breaker. When a certain number of trips have
occurred, adjustable between 1 and 40 in a definite time period (30 minutes), an output signal is
generated that can be connected to operate one of the physical
Auxiliary Contact Outputs
.
On
7IRD-A/J
models, this output will disable any further reclose initiation by placing the unit in
Recloser Lockout Due To Open Breaker Status
. This condition will reset only after a
Manual
Close Command
or a loss of auxiliary power.
