11.2.6.1 IntroductionThe purpose of Circuit breaker (SXCBR) is to provide the actual status of positionsand to perform the control operations, that is, pass all the commands to primaryapparatuses in the form of circuit breakers via output boards and to supervise theswitching operation and position.11.2.6.2 Principle of operationThe users of the Circuit breaker function (SXCBR) is other functions such as forexample, switch controller, protection functions, autorecloser function or an IEC61850 client residing in another IED or the operator place. This switch functionexecutes commands, evaluates block conditions and evaluates different timesupervision conditions. Only if all conditions indicate a switch operation to beallowed, the function performs the execution command. In case of erroneousconditions, the function indicates an appropriate "cause" value.SXCBR has an operation counter for closing and opening commands. The countervalue can be read remotely from the operator place. The value is reset from abinary input or remotely from the operator place by configuring a signal from theSingle Point Generic Control 8 signals (SPC8GGIO) for example.Local/Remote switchOne binary input signal LR_SWI is included in SXCBR to indicate the local/remote switch position from switchyard provided via the I/O board. If this signal isset to TRUE it means that change of position is allowed only from switchyardlevel. If the signal is set to FALSE it means that command from IED or higherlevel is permitted. When the signal is set to TRUE all commands (for change ofposition) from internal IED clients are rejected, even trip commands fromprotection functions are rejected. The functionality of the local/remote switch isdescribed in figure 176.From I/O switchLRTRUEFALSELocal= Operation atswitch yard levelRemote= Operation atIED or higher levelen05000096.vsdIEC05000096 V1 ENFigure 176: Local/Remote switchBlocking principlesSXCBR includes several blocking principles. The basic principle for all blockingsignals is that they will affect commands from all other clients for example,operators place, protection functions, autoreclosure and so on.1MRK 505 208-UEN B Section 11Control339Technical reference manual
