ABB RELION 620 Series Technical Manual page 883

1MAC504801-IB E
12.6
620 series ANSI
Technical Manual
Peak-to-peak with peak backup
The peak-to-peak with peak backup measurement principle is selected with the
Measurement mode setting using the value "P-to-P+backup". It is similar to the peak-to-
peak mode, with the exception that it has been enhanced with the peak backup. In the peak-
to-peak with peak backup mode, the function starts with two conditions: the peak-to-peak
value is above the set pickup current or the peak value is above two times the set Pickup
value. The peak backup is enabled only when the function is used in the DT mode in high
and instantaneous stages for faster operation.
Calculated measurements
Calculated residual current and voltage
The residual current is calculated from the phase currents according to equation:
Io = − ( I + I + I )
A B C
GUID-B9280304-8AC0-40A5-8140-2F00C1F36A9E V1 EN
The residual voltage is calculated from the phase-to-ground voltages when the VT
connection is selected as "Wye" with the equation:
Vo ( V V V )
A B C
= + +
GUID-4E68CD47-9DBB-4DAD-A092-BD69DA5863F3 V1 EN
Sequence components
The phase-sequence current components are calculated from the phase currents according
to:
I ( I I I ) / 3
0 A B C
= + +
GUID-2319C34C-8CC3-400C-8409-7E68ACA4F435 V2 EN
2
I = ( I + ⋅ a I + a ⋅ I ) /
1 A B C
GUID-02E717A9-A58F-41B3-8813-EB8CDB78CBF1 V2 EN
2
I = ( I + a ⋅ I + ⋅ a I ) /
2 A B C
GUID-80F92D60-0425-4F1F-9B18-DB2DEF4C2407 V2 EN
The phase-sequence voltage components are calculated from the phase-to-ground
voltages when VT connection is selected as "Wye" with the formulae:
V ( V V V ) / 3
0 A B C
= + +
GUID-49CFB460-5B74-43A6-A72C-AAD3AF795716-ANSI V1 EN
General function block features
3
3
Section 12
(Equation 117)
(Equation 118)
(Equation 119)
(Equation 120)
(Equation 121)
(Equation 122)
877