GE Multilin G30 Generator Protection System 6-156 ACTUAL VALUES 6.3 METERING6DELTA-CONNECTED INSTRUMENT TRANSFORMERS:The zero-sequence voltage is not measurable under the Delta connection of instrument transformers and is defaulted tozero. The table below shows an example of symmetrical components calculations for the ABC phase rotation.* The power system voltages are phase-referenced – for simplicity – to VAG and VAB, respectively. This, however, is arelative matter. It is important to remember that the G30 displays are always referenced as specified under SETTINGS SYSTEM SETUP POWER SYSTEM FREQUENCY AND PHASE REFERENCE.The example above is illustrated in the following figure.Figure 6–3: MEASUREMENT CONVENTION FOR SYMMETRICAL COMPONENTS• ABC phase rotation: • ACB phase rotation:Table 6–1: SYMMETRICAL COMPONENTS CALCULATION EXAMPLESYSTEM VOLTAGES, SEC. V * VTCONN.RELAY INPUTS, SEC. V SYMM. COMP, SEC. VVAG VBG VCG VAB VBC V CA F5AC F6AC F7AC V 0 V 1 V 213.9∠0°76.2∠–125°79.7∠–250°84.9∠–313°138.3∠–97°85.4∠–241°WYE 13.9∠0°76.2∠–125°79.7∠–250°19.5∠–192°56.5∠–7°23.3∠–187°UNKNOWN (only V1 and V2can be determined)84.9∠0°138.3∠–144°85.4∠–288°DELTA 84.9∠0°138.3∠–144°85.4∠–288°N/A 56.5∠–54°23.3∠–234°V_0 N/A=V_1 1 30– °∠3 3-------------------- V AB aV BC a2V CA+ +( )=V_2 1 30°∠3 3----------------- V AB a2V BC aV CA+ +( )=V_0 N/A=V_1 1 30°∠3 3----------------- V AB a2V BC aV CA+ +( )=V_2 1 30– °∠3 3-------------------- V AB aV BC a2V CA+ +( )=827844A1.CDRABCWYE VTs102ABCDELTA VTs12SYSTEM VOLTAGES SYMMETRICALCOMPONENTSUR phase anglereferenceUR phase anglereferenceUR phase anglereferenceUR phase anglereference
