Functions
2.23 Auxiliary Functions
SIPROTEC, 7SJ62/64, Manual
C53000-G1140-C207-2, Release date 01.2008
340
2.23.2.2 Circuit Breaker Maintenance
General
The procedures aiding in CB maintenance allow maintenance intervals of the CB poles to be carried out when
their actual degree of wear makes it necessary. Saving on maintenance and servicing costs is one of the main
benefits this functionality offers.
The universal CB maintenance accumulates the tripping currents of the trips initiated by the protective functions
and comprises the four following autonomous subfunctions:
• Summation tripping current (ΣI-procedure)
• Summation of tripping powers (ΣI
x
-procedure)
• Two-point procedure for calculating the remaining lifetime (2P-procedure)
• Sum of all Squared Fault Current Integral (I
2
t-procedure);
Measured value acquisition and preparation operates phase-selectively for all four subfunctions. The three
results are each evaluated using a threshold which is specific for each procedure (see Figure 2-130).
Figure 2-130 Diagram of CB maintenance procedures
The ΣI procedure is always present and active as a basic functionality. However, the other procedures (ΣI
x
, 2P
and I
2
t) can be selected via a common configuration parameter.
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