ABB REC650 ANSI Technical Manual page 517

1MRK 511 287-UUS A
Technical manual
F
A
Z pZ
I
A L
A
V
A
ANSI01000171 V1 EN
Figure 225: Fault on transmission line fed from both ends
From figure 225 it is evident that:
= × × + ×
V I p Z I R
A A L F F
EQUATION1595 V1 EN
Where:
I is the line current after the fault, that is, pre-fault current plus current change due to the fault,
A
I is the fault current and
F
is a relative distance to the fault
p
The fault current is expressed in measurable quantities by:
I
F A
------- -
I =
F
D
A
EQUATION96 V1 EN
Where:
I is the change in current at the point of measurement, IED A and
FA
D is a fault current-distribution factor, that is, the ratio between the fault current at line end A and the
A
total fault current.
For a single line, the value is equal to:
L
B
(1-p).Z
I
L
B
I
F
R
F
xx01000171_ansi.vsd
Section 12
Monitoring
Z
B
(Equation 61)
(Equation 62)
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