Schweitzer Engineering SEL-387-0, Instruction Manual

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5.10
SEL-387-0, -5, -6 Relay Instruction Manual Date Code 20170601
Metering and Monitoring
Breaker Monitor
Figure 5.4 Trip Bus Sensing With Relay Input
Breaker Wear Curve
Description and
Settings
Based on maintenance curves supplied by manufacturers of the breakers, a
contact wear curve for each breaker is constructed (
Figure 5.5 ).
Figure 5.5 Breaker Contact Wear Curve
The curve is a plot of Close/Open operations versus interrupted current in
kiloamperes (kA). The scales are logarithmic on both axes. For each
Breaker
n , three points are input in the Global setting area as relay settings.
The points are defined by pairs of coordinates of current and operations. For
Breaker
n , these are the points (B n KAP1, B n COP1), (B n KAP2, B n COP2),
TC
52A-1
CS/T (Control
Switch Trip) BKMON1=
IN106
SEL-387
Trip Bus
Other
External Trips
(+)
(–)
OUT101=
TRIP 1
52-1
Trip Coil
(B1KAP1, B1COP1)
(minimum)
e.g., (1.2 kA, 10000)
e.g., (8 kA, 150)
(B1KAP2, B1COP2)
(middle)
e.g., (20 kA, 12)
(B1KAP3, B1COP3)
(maximum)
Number of Close/O
pen O
perations
kA Interrupted per Operation
Breaker 1 (25 kV)
Contact Wear Curve
(100% Wear)
(Log-Log Scales)