12.1.6 Monitored dataTable 212:SESRSYN (25) Monitored dataName Type Values (Range) Unit DescriptionVDIFFME REAL - - Calculated difference ofvoltage in p.u of set voltagebase valueFRDIFFME REAL - Hz Calculated difference offrequencyPHDIFFME REAL - deg Calculated difference of phaseangleVbus REAL - kV Bus voltageVLine REAL - kV Line voltage12.1.7 Operation principle12.1.7.1 Basic functionalityThe synchronism check function measures the conditions across the circuit breaker andcompares them to set limits. The output is only given when all measured quantities aresimultaneously within their set limits.The energizing check function measures the bus and line voltages and compares them toboth high and low threshold detectors. The output is given only when the actual measuredquantities match the set conditions.The synchronizing function measures the conditions across the circuit breaker, and alsodetermines the angle change occurring during the closing delay of the circuit breaker,from the measured slip frequency. The output is given only when all measured conditionsare simultaneously within their set limits. The issue of the output is timed to give closureat the optimal time including the time for the circuit breaker and the closing circuit.For single circuit breaker double bus and breaker-and-a-half circuit breaker arrangements,the SESRSYN (25) function blocks have the capability to make the necessary voltageselection. For single circuit breaker double bus arrangements, selection of the correctvoltage is made using auxiliary contacts of the bus disconnectors. For breaker-and-a-halfcircuit breaker arrangements, correct voltage selection is made using auxiliary contacts ofthe bus/line disconnectors as well as the circuit breakers.The internal logic for each function block as well as, the input and outputs, and the settingswith default setting and setting ranges is described in this document. For applicationrelated information, please refer to the application manual.1MRK 502 048-UUS A Section 12Control351Technical manual
