ABB REC650 - Page 484

U
A
I
A
p Z
1L
I
FA
D
A
--------
R
F
I
0P
Z
0M
×+×+× ×=
EQUATION100 V1 EN (Equation 66)
Where:
I
0P
is a zero sequence current of the parallel line,
Z
0M
is a mutual zero sequence impedance and
D
A
is the distribution factor of the parallel line, which is:
D
A
1 p–( ) Z
A
Z
AL
Z
B
+ +( ) Z
B
+×
2 Z
A
Z
L
2 Z
B
×+ +×
-----------------------------------------------------------------------------
=
EQUATION101 V1 EN
The K
N
compensation factor for the double line becomes:
K
N
Z
0L
Z
1L
–
3 Z
1L
×
------------------------
Z
0M
3 Z
1L
×
-----------------
I
0P
I
0A
-------
×+=
EQUATION102 V1 EN (Equation 67)
From these equations it can be seen, that, if Z
0m
= 0, then the general fault location
equation for a single line is obtained. Only the distribution factor differs in these two
cases.
Because the D
A
distribution factor according to equation 64 or 66 is a function of p,
the general equation
66 can be written in the form:
p
2
p K
1
K
2
K
3
R
F
×–+×– 0=
EQUATION103 V1 EN
(Equation 68)
Where:
K
1
U
A
I
A
Z
L
×
----------------
Z
B
Z
L
Z
A DD
+
---------------------------
1+ +=
EQUATION104 V1 EN
(Equation 69)
K
2
U
A
I
A
Z
L
×
----------------
Z
B
Z
L
Z
A DD
+
---------------------------
1+
è ø
æ ö
×=
EQUATION105 V1 EN (Equation 70)
K
3
I
FA
I
A
Z
L
×
----------------
Z
A
Z
B
+
Z
1
Z
A DD
+
---------------------------
1+
è ø
æ ö
×=
EQUATION106 V1 EN (Equation 71)
Section 12 1MRK 511 287-UEN A
Monitoring
478
Technical manual