5.24
SEL-751A Relay
Instruction Manual
Date Code 20100129
Metering and Monitoring
Breaker Monitor
Breaker
Monitor Output
When the breaker maintenance curve for a particular phase (A, B, or C)
reaches the 100 percent wear level (see
), a corresponding Relay
Word bit (BCWA, BCWB, or BCWC) asserts.
EXAMPLE 5.1
Example Applications
These logic outputs can be used to alarm:
OUT
xxx
=
BCW
or drive the relay to lockout the next time the relay trips:
79DTL =
TRIP AND BCW
View or Reset
Breaker Monitor
Information
Accumulated breaker wear/operations data is retained if the relay loses power
or the breaker monitor is disabled (setting EBMON = N). The accumulated
data can only be reset if the
BRE R
command is executed (see the following
discussion on the
BRE R
command).
Via Serial Port
. The
BRE
command displays the following
information:
➤
Accumulated number of relay initiated trips
➤
Accumulated interrupted current from relay initiated trips
➤
Accumulated number of externally initiated trips
➤
Accumulated interrupted current from externally initiated trips
➤
Percent circuit breaker contact wear for each phase
➤
Date when the preceding items were last reset (via the
BRE R
command)
. The
BRE W
command allows the trip
counters, accumulated values, and percent breaker wear to be preloaded for
each individual phase.
The
BRE R
command resets the accumulated values and the percent wear for
all three phases. For example, if breaker contact wear has reached the 100
percent wear level for A-phase, the corresponding Relay Word bit BCWA
asserts (BCWA = logical 1). Execution of the
BRE R
command resets the
wear levels for all three phases back to 0 percent and consequently causes
Relay Word bit BCWA to deassert (BCWA = logical 0).
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.
Section 8: Front-Panel Operations
for details.
Relay Word Bits
Definition
BCWA
Phase A breaker contact wear has reached the 100 percent wear level
BCWB
Phase B breaker contact wear has reached the 100 percent wear level
BCWC
Phase C breaker contact wear has reached the 100 percent wear level
BCW
BCWA or BCWB or BCWC
Summary of Contents for 751A
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