ABB RELION REX640 Technical Manual page 896

Section 4
Protection functions
890
Three-phase measuring element reach = Z + R =
GUID-878BFBA3-D18F-48E0-90F4-BFDD29BC49D4 V1 EN
R
1
~
GUID-B424276E-35A7-4DCA-8559-3948391BF753 V1 EN
Figure 482: The fault loop impedance model for three-phase impedance
measuring element
R Positive-sequence resistance from measuring point to fault location
1
X Positive-sequence reactance from measuring point to fault location
1
R Physical fault resistance per phase, for example, arc resistance
F
The three-phase impedance measuring element measures the physical
fault resistance per phase. The resistive reach setting is common for
three-phase and phase-to-phase impedance measuring elements.
The time delay of operation is defined with the PP operate delay Znx (x = 1... 5)
setting. The timer can be disabled with the setting PP Op delay Mod Znx = "False".
This blocks the OPERATE_Zx (x = 1... 5) output of the three-phase measuring
elements.
Entering the line reach
The line reach is entered in primary ohms. The impedance format is selected with
Impedance mode Zn = "Rectangular" for the vectors R, X and "Polar" for the
magnitude and angle.
Impedance mode Zn = Rectangular
In case of phase-to-phase or three-phase impedance measuring elements, the line
reach is defined with:
• Resistive reach: R1 zone x (x = 1...5)
• Reactive reach: X1 zone x (x = 1...5)
1 F
X
1
R
F
1MRS759142 C
R + j X X + R
1 1 F
X
X
1
R
F
R
1
Technical Manual
(Equation 223)
R
REX640