Table 712: Positive-sequence impedance values for typical 11 kV conductors, “Flat” tower
configuration assumed
Name R1 [Ω/km] X1 [Ω/km]
ACSR 50 SQ.mm 0.532 0.373
ACSR 500 SQ.mm 0.0725 0.270
Table 713: Positive-sequence impedance values for typical 10/20 kV conductors, “Flat” tower
configuration assumed
Name R1 [Ω/km] X1 [Ω/km]
Al/Fe 36/6 Sparrow 0.915 0.383
Al/Fe 54/9 Raven 0.578 0.368
Al/Fe 85/14 Pigeon 0.364 0.354
Al/Fe 93/39 Imatra 0.335 0.344
Al/Fe 108/23 Vaasa 0.287 0.344
Al/Fe 305/39 Duck 0.103 0.314
Table 714: Positive-sequence impedance values for typical 33 kV conductors, “Flat” tower
configuration assumed
Name
R1 [Ω/km] X1 [Ω/km]
ACSR 50 sq.mm 0.529 0.444
ACSR 100 sq.mm 0.394 0.434
ACSR 500 sq.mm 0.0548 0.346
Zero-sequence impedance values
Location of ground faults requires both positive-sequence and zero-sequence
impedances. For short circuit faults, zero-sequence impedances are not required.
The positive-sequence impedance per unit values for the lines are typically known or can
easily be obtained from data sheets. The zero-sequence values are generally not as easy to
obtain as they depend on the actual installation conditions and configurations. Sufficient
accuracy can, however, be obtained with rather simple calculations using the following
equations, which apply per phase for symmetrically transposed three-phase aluminium
overhead lines without ground wires.
R Hz R km
0
50 1 0 14804[ ] . [ / ]≈ + Ω
GUID-087D1F51-4C8C-4CF4-ACE5-9F43AF0DD3FC V1 EN (Equation 152)
Section 5 1MAC059074-MB A
Protection related functions
816 615 series ANSI
Technical Manual
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