Date Code 20011205
Breaker Monitor and Metering Functions
8-13
SEL-311A Instruction Manual
Via Front Panel
The information and reset functions available via the previously discussed serial port commands
BRE
and
BRE R
are also available via the front-panel OTHER pushbutton. See Figure 11.3 in
Section 11: Front-Panel Interface
.
Determination of Relay-Initiated Trips and Externally Initiated Trips
See
BRE Command (Breaker Monitor Data)
in
Section 10: Serial Port Communications and
Commands
. Note in the
BRE
command response that the accumulated number of trips and
accumulated interrupted current are separated into two groups of data: that generated by
relay-initiated trips (Rly Trips) and that generated by externally initiated trips (Ext Trips). The
categorization of this data is determined by the status of the TRIP Relay Word bit when the
SEL
OGIC
control equation breaker monitor initiation setting BKMON operates.
Refer to Figure 8.3 and the accompanying explanation. If BKMON newly asserts (logical 0 to
logical 1 transition), the relay reads in the current values (Phases A, B, and C). Now the decision
has to be made: where is this current and trip count information accumulated? Under
relay-initiated trips or externally initiated trips?
To make this determination, the status of the TRIP Relay Word bit is checked at the instant
BKMON newly asserts (TRIP is the logic output of Figure 5.1). If TRIP is asserted
(TRIP = logical 1), the current and trip count information is accumulated under relay-initiated
trips (Rly Trips). If TRIP is deasserted (TRIP = logical 0), the current and trip count information
is accumulated under externally initiated trips (Ext Trips).
Regardless of whether the current and trip count information is accumulated under relay-initiated
trips or externally initiated trips, this same information is routed to the breaker maintenance
curve for continued breaker wear integration (see Figure 8.3 through Figure 8.7).
Setting Example
As discussed previously, the SEL
OGIC
control equation breaker monitor initiation may be set:
BKMON = TRIP
Thus, any new assertion of BKMON will be deemed a relay trip, and the current and trip count
information is accumulated under relay-initiated trips (Rly Trips).
Additional Example
Refer to Figure 8.8. Output contact OUT101 is set to provide tripping:
OUT101 = TRIP
Note that optoisolated input IN106 monitors the trip bus. If the trip bus is energized by output
contact OUT101, an external control switch, or some other external trip, then IN106 is asserted.
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