11.6 Calculated measurementsCalculated residual current and voltageThe residual current is calculated from the phase currents according to equation:Io I I IA B C= − + +( )GUID-B9280304-8AC0-40A5-8140-2F00C1F36A9E V1 EN (Equation 110)The residual voltage is calculated from the phase-to-earth voltages when the VTconnection is selected as “Wye” with the equation:Uo U U UA B C= + +( ) / 3GUID-03909E83-8AA3-42FF-B088-F216BBB16839 V1 EN (Equation 111)Sequence componentsThe phase-sequence current components are calculated from the phase currentsaccording to:I I I IA B C0 3= + +( ) /GUID-2319C34C-8CC3-400C-8409-7E68ACA4F435 V2 EN (Equation 112)I I a I a IA B C1 2 3= + ⋅ + ⋅( ) /GUID-02E717A9-A58F-41B3-8813-EB8CDB78CBF1 V2 EN (Equation 113)I I a I a IA B C2 2 3= + ⋅ + ⋅( ) /GUID-80F92D60-0425-4F1F-9B18-DB2DEF4C2407 V2 EN (Equation 114)The phase-sequence voltage components are calculated from the phase-to-earthvoltages when VT connection is selected as “Wye” with the equations:U U U UA B C0 3= + +( ) /GUID-49CFB460-5B74-43A6-A72C-AAD3AF795716 V2 EN (Equation 115)U U a U a UA B C1 2 3= + ⋅ + ⋅( ) /GUID-7A6B6AAD-8DDC-4663-A72F-A3715BF3E56A V2 EN (Equation 116)U U a U a UA B C2 2 3= + ⋅ + ⋅( ) /GUID-6FAAFCC1-AF25-4A0A-8D9B-FC2FD0BCFB21 V1 EN (Equation 117)When VT connection is selected as “Delta”, the positive and negative phasesequence voltage components are calculated from the phase-to-phase voltagesaccording to the equations:U U a UAB BC1 2 3= − ⋅( ) /GUID-70796339-C68A-4D4B-8C10-A966BD7F090C V2 EN (Equation 118)U U a UAB BC2 3= − ⋅( ) /GUID-C132C6CA-B5F9-4DC1-94AF-FF22D2F0F12A V2 EN (Equation 119)1YHT530004D05 D Section 11General function block features615 series 841Technical Manual
