ABB RELION 650 SERIES, Technical Manual

Page: 109 / 942

The plain Mho circle has the characteristic as in figure 37 . The condition for
deriving the angle β is according to equation 3 .
β = −
( )
−
( )
⋅ arg arg U I Z U
L L L L set pol 1 2 1 2
1
IECEQUATION15027 V1 EN-US
(Equation 3)
where
U
L1L2
EQUATION1790 V2 EN-US
is the voltage vector difference between phases L1 and L2
I
L1L2
EQUATION1791 V2 EN-US
is the current vector difference between phases L1 and L2
Z
set
1
is the positive sequence impedance setting for phase-to-phase fault in zone direction
For Zone 1,
Z R PPZ j X PPZ
set
1 1 1 1 1 = + ⋅
IECEQUATION15011 V1 EN-US
(Equation 4)
where
R1PPZ1 is the positive sequence resistive reach for phase-to-phase fault for zone 1
X1PPZ1 is the positive sequence reactance reach for phase-to-phase fault for zone 1
For Zone 2-5 and RV
Z R Zx j X Zx
set
1 1 1
= + ⋅
IECEQUATION15012 V1 EN-US
(Equation 5)
where
R1Zx
is the positive sequence resistive reach for zone x (x=2-5 and RV)
X1Zx
is the positive sequence reactance reach for zone x (x=2-5 and RV)
U
pol
is the polarizing voltage
Operation occurs if 90°≤β≤270°
1MRK 506 382-UEN A
Section 6
Impedance protection
Line distance protection REL650 2.2 IEC 103
Technical manual