8.12
SEL-351A Relay Instruction Manual Date Code 20080213
Breaker Monitor and Metering
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 Figure 8.7), a corresponding Relay
Word bit (BCWA, BCWB, or BCWC) asserts.
Example Applications
These logic outputs can be used to alarm:
OUT105 = BCW
or drive the relay to lockout the next time the relay trips:
79DTL = TRIP * 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
See BRE Command (Breaker Monitor Data) on page 10.15. 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)
See BRE n Command (Preload/Reset Breaker Wear) on page 10.33. 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 (Only on Models With LCD)
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.
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 + BCWB + BCWC
Courtesy of NationalSwitchgear.com
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