8-14
Breaker Monitor and Metering Functions
Date Code 20011205
SEL-311A Instruction Manual
Figure 8.8: Input IN106 Connected to Trip Bus for Breaker Monitor Initiation
If the SEL
OGIC
control equation breaker monitor initiation setting is set:
BKMON = IN106
then the SEL-311A Relay breaker monitor sees all trips.
If output contact OUT101 asserts, energizing the trip bus, the breaker monitor will deem it a
relay-initiated trip. This is because when BKMON is newly asserted (input IN106 energized),
the TRIP Relay Word bit is asserted. Thus, the current and trip count information is accumulated
under relay-initiated trips (Rly Trips).
If the control switch trip (or some other external trip) asserts, energizing the trip bus, the breaker
monitor will deem it an externally initiated trip. This is because when BKMON is newly
asserted (input IN106 energized), the TRIP Relay Word bit is deasserted. Thus, the current and
trip count information is accumulated under externally initiated trips (Ext Trips).
S
TATION
DC B
ATTERY
M
ONITOR
The station dc battery monitor in the SEL-311A Relay can alarm for under- or overvoltage dc
battery conditions and give a view of how much the station dc battery voltage dips when tripping,
closing, and other dc control functions take place. The monitor measures the station dc battery
voltage applied to the rear-panel terminals labeled Z25 and Z26 (see Figure 1.2). The station dc
battery monitor settings (DCLOP and DCHIP) are available via the
SET G
command (see
Table 9.1 in
Section 9: Setting the Relay
and also Settings Sheet 12 in the back of
Section 9
).
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