In normal security, the command is processed and the resulting position is notsupervised. However with enhanced security, the command is processed and theresulting position is supervised.Normal security means that only the command is evaluated and the resultingposition is not supervised. Enhanced security means that the command is evaluatedwith an additional supervision of the status value of the control object. Thecommand sequence with enhanced security is always terminated by aCommandTermination service primitive and an AddCause telling if the commandwas successful or if something went wrong.Control operation can be performed from the local HMI with authority control if sodefined.The switch controller SCSWI initializes and supervises all functions to properlyselect and operate switching primary apparatuses. Each of the 10 switch controllersSCSWI may handle and operate on one three-phase apparatus.Each of the 3 circuit breaker controllers SXCBR provides the actual position statusand pass the commands to the primary circuit breaker and supervises the switchingoperation and positions.Each of the 9 circuit switch controllers SXSWI provides the actual position statusand pass the commands to the primary disconnectors and earthing switches andsupervises the switching operation and positions.12.4.2 Operation principle M13423-4 v8A bay can handle, for example a power line, a transformer, a reactor, or a capacitorbank. The different primary apparatuses within the bay can be controlled via theapparatus control functions directly by the operator or indirectly by automaticsequences.Because a primary apparatus can be allocated to many functions within aSubstation Automation system, the object-oriented approach with a function blockthat handles the interaction and status of each process object ensures consistency inthe process information used by higher-level control functions.Primary apparatuses such as breakers and disconnectors are controlled andsupervised by one function block (SCSWI) each. Because the number and type ofsignals used for the control of a breaker or a disconnector are almost the same, thesame function block type is used to handle these two types of apparatuses.The SCSWI function block is connected to an SXCBR function block (for circuitbreakers). The physical process in the switchyard is connected to these twofunction blocks via binary inputs and outputs.Three types of function blocks are available to cover most of the control andsupervision within the bay. These function blocks are interconnected to form a1MRK 505 394-UEN A Section 12ControlLine differential protection RED650 2.2 IEC 349Technical manual
