ABB RED650, Technical Manual, Page: 604 / 926

p
2
p Re K
1
( )
Re K
2
( )
R
F
Re K
3
( )
0 =
×
– +
×
–
EQUATION107 V1 EN-US
(Equation 90)
p Im K
1
( )
Im K
2
( )
R
F
Im K
3
( )
0
=
× ×
–
×
+
× ×
–
EQUATION108 V1 EN-US
(Equation 91)
If the imaginary part of K
3
is not zero, R
F
can be solved according to equation 91 ,
and then inserted to equation 90 . According to equation 90 , the relative distance to
the fault is solved as the root of a quadratic equation.
Equation 90 gives two different values for the relative distance to the fault as a
solution. A simplified load compensated algorithm, which gives an unequivocal
figure for the relative distance to the fault, is used to establish the value that should
be selected.
If the load compensated algorithms according to the above do not give a reliable
solution, a less accurate, non-compensated impedance model is used to calculate
the relative distance to the fault.
15.9.7.3 The non-compensated impedance model
M14983-121 v3
In the non-compensated impedance model, I
A
line current is used instead of I
FA
fault current:
U
A
p Z
1L
I
A
R
F
I
A
×
+
× ×
=
EQUATION109 V1 EN-US
(Equation 92)
Where:
I
A
is according to table 417 .
The accuracy of the distance-to-fault calculation, using the non-compensated
impedance model, is influenced by the pre-fault load current. So, this method is
only used if the load compensated models do not function.
15.9.7.4 IEC 60870-5-103
M14983-135 v2
The communication protocol IEC 60870-5-103 may be used to poll fault location
information from the IED to a master (that is station HSI). There are two outputs
that must be connected to appropriate inputs on the function block I103StatFltDis,
FLTDISTX gives distance to fault (reactance, according the standard) and
CALCMADE gives a pulse (100 ms) when a result is obtainable on FLTDISTX
output.
Section 15
1MRK 505 394-UEN A
Monitoring
598 Line differential protection RED650 2.2 IEC
Technical manual