Schweitzer Engineering Laboratories SEL-387E - Breaker Wear Example; Breaker Monitor Reporting

5-14 Metering and Monitoring Date Code 20080110
SEL-387E Instruction Manual
Breaker Wear Example
A breaker having the wear curve of Figure 5.5 experiences a fault current interruption of
17000 A. Previous accumulated wear is 44 percent.
The fault current falls between B
n KAP2 (8 kA) and B n KAP3 (20 kA). The second equation is
used to calculate O(I).
(
)
81.1800041.0•4628417•46284IO
756.2
===
−
Incremental Percent Wear = 100/18.81 = 5.32%
Cumulative Percent Wear = 44 + 5.32 = 49.32% (which appears as 49% in BRE listing)
Breaker Monitor Reporting
The accumulators for each breaker can be reviewed either by a serial port command BRE or via
the front-panel display, using the OTHER button menu.
The report lists all breakers, giving the number of internal and external trips for each breaker, the
total accumulated RMS current by phase, and the percent wear by pole. The operation
accumulators for each trip type have a maximum value of 65000 trips. The current accumulators
for each trip type have a maximum value of 99999.00 kA RMS. Percent wear never exceeds 100
percent. The accumulators can be reset by the serial port command
BRE n R or via the OTHER
front-panel pushbutton menu. The serial port report format is shown below.
=>>BREAKER <Enter>
XFMR 1 Date: MM/DD/YY Time: HH:MM:SS.SSS
STATION A
BREAKER 1
Int Trips= 12345 IAW1= 12345 IBW1= 12345 ICW1= 12345 kA(pri)
Ext Trips= 12345 IAW1= 12345 IBW1= 12345 ICW1= 12345 kA(pri)
Percent Wear: POLE1= 123 POLE2= 123 POLE3= 123
BREAKER 2
Int Trips= 12345 IAW2= 12345 IBW2= 12345 ICW2= 12345 kA(pri)
Ext Trips= 12345 IAW2= 12345 IBW2= 12345 ICW2= 12345 kA(pri)
Percent Wear: POLE1= 123 POLE2= 123 POLE3= 123
BREAKER 3
Int Trips= 12345 IAW3= 12345 IBW1= 12345 ICW3= 12345 kA(pri)
Ext Trips= 12345 IAW3= 12345 IBW1= 12345 ICW3= 12345 kA(pri)
Percent Wear: POLE1= 123 POLE2= 123 POLE3= 123
LAST BREAKER MONITOR RESET FOR Bkr1: MM/DD/YY HH:MM:SS.SSS
Bkr2: MM/DD/YY HH:MM:SS.SSS
Bkr3: MM/DD/YY HH:MM:SS.SSS
=>>
T HROUGH -F AULT E VENT M ONITOR
Figure 5.6 shows a distribution feeder fault beyond the protection zone of the SEL-387E Relay.
Nevertheless, the fault current passes through the transformer bank, subjecting the windings to