ABB RED650, Technical Manual, Page: 137 / 926


1 L
U
set N
Z K I 1 0 3
 
set N L L comp
Z K I I U U 1 ) 0 3 (
1 1
    
pol
U
I
L1
•R
I
L1
•jX
set L
Z I 1
1

IEC15000059-1-en.vsdx
IEC15000059 V1 EN-US
Figure 51: Simplified offset mho characteristic and vector diagram for phase
L1-to-earth fault
Operation occurs if 90°≤β≤270°.
Offset mho
GUID-B1EF3931-7B86-4C7B-BCEA-3034482BA240 v2
The condition for operation of offset mho at phase-to-earth fault is that the angle β
between the two compensated voltages is equal to or greater than 90°, see figure
52 . The angle will be 90° for fault location on the boundary of the circle.
 


1 1 1 1
arg ( 3 0 ) 1 arg ( 3 0 ) 1
L L N set L L N set
U I I K Z U I I K Z

 
          
 
IECEQUATION15022 V2 EN-US
(Equation 12)
1MRK 505 394-UEN A
Section 7
Impedance protection
Line differential protection RED650 2.2 IEC 131
Technical manual