Circuit Breaker Maintenance - Siemens SIPROTEC 4 7SJ61 Manual

Functions
2.17 Auxiliary Functions
2.17.2.2

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 func-
tions and comprises the four following autonomous subfunctions:
•
Summation tripping current (ΣΙ-procedure)
•
Summation of tripping powers (ΣΙ
•
Two-point procedure for calculating the remaining lifetime (2P-procedure)
•
Sum of all Squared Fault Current Integral (I
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
[schema-lsw-171103-kn, 1, en_US]
Figure 2-75
The ΣΙ procedure is always present and active as a basic functionality. However, the other procedures (ΣΙx, 2P
and Ι 2 t) can be selected via a common configuration parameter.
As the load on the switch depends on the current amplitude and duration of the actual switching action,
including arc deletion, determination of the start and end criteria is of great importance. The procedures ΣΙx,
2P and Ι 2 t make use of the same criteria for that purpose. The logic of the start and end criterion is illustrated
in Figure 2-76.
The start criterion is fulfilled by an internal protective tripping initiated by the group indication "device TRIP".
Trips initiated via the internal control function are taken into consideration for the circuit breaker maintenance
if the respective command is indicated via the parameter 265 Cmd.via control. An externally initiated trip
196
x -procedure)
Diagram of CB maintenance procedures
2 t-procedure);
C53000-G1140-C210-6, Edition 05.2016
Figure 2-75.).
SIPROTEC 4, 7SJ61, Manual