mined by the maximum number of switching cycles at rated short-circuit breaking current I
sc
. The 4 associated
values can be configured with the parameters Rated normal current, Switching cycles at Ir,
Rated short-circ.cur. Isc, and Switching cycles at Isc.
[DwCBWOpC, 1, en_US]
Figure 10-36
Diagram of Switching Cycles for the 2P Method
As shown in the preceding figure, a double-logarithmic diagram, the straight line between P1 and P2 can be
expressed by the following exponential function:
[FoCBW2P1-301012-01.tif, 1, en_US]
Where:
I
trip
Tripping/opening current
I
rated
Rated normal current
m Slope coefficient
b Switching cycles at rated normal current
n Number of switching cycles
The general line equation for the double-logarithmic representation can be derived from the exponential func-
tion and leads to the coefficients b and m.
Measured Values, Energy Values, and Supervision of the Primary System
10.12 Circuit-Breaker Wear Monitoring
SIPROTEC 5, Overcurrent Protection, Manual 1361
C53000-G5040-C017-8, Edition 07.2017
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