Operating Hours
The operating hours under load are also stored (= the current value in at least one phase is greater than the
limit value BkrClosed I MIN set under address 212).
Hours Meter "CB open"
A meter can be realized as a CFC application if it adds up the number of hours in state “Circuit Breaker open”
similarly to the operating hours meter. The universal hours meter is linked to a respective binary input and
counts if the binary input is active. Alternatively, the undershooting of the parameter value 212 BkrClosed
I MIN may be used as a criterion for starting the meter. The meter can be set or reset. A CFC application
example for such meter is available on the Internet (SIPROTEC Download Area).
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 func-
tions and comprises the four following autonomous subfunctions:
•
Summation tripping current (ΣΙ-procedure)
•
Summation of tripping powers (ΣΙ
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 2-138.).
2.25.2.2
Functions
2.25 Auxiliary Functions
320 SIPROTEC 4, 7SJ62/64, Manual
C53000-G1140-C207-8, Edition 08.2016
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