Do long-distance power lines exhibit hysteresis losses? These lines are mostly aluminum but they do have a core of steel for added strength.

  • $\begingroup$ I haven't heard of hysteresis losses in power lines. As I understand it the main loss is Joule heating. $\endgroup$
    – Bob D
    Aug 8, 2023 at 21:11
  • 1
    $\begingroup$ There is nothing wrong with this question, it is clear, precise and to the point. It may get more attention in the electronics.stackexchange.com but it is quite appropriate here. $\endgroup$
    – hyportnex
    Aug 8, 2023 at 21:33

1 Answer 1


Yes, there are hysteresis losses, although not always significant. From the Wikipedia Aluminium-conductor steel-reinforced cable page:

The resistances of ASCR conductors are tabulated for different conductor designs by the manufacturer at DC and AC frequency assuming specific operating temperatures. The reasons that resistance changes with frequency are largely due to the skin effect, the proximity effect, and hysteresis loss.


Hysteresis in an ACSR conductor is due to the atomic dipoles in the steel core changing direction due to induction from the 60 or 50 Hertz AC current in the conductor. Hysteresis losses in ACSR are undesirable and can be minimized by using an even number of aluminium layers in the conductor. Due to the cancelling effect of the magnetic field from the opposing lay (right-hand and left-hand) conductors for two aluminium layers there is significantly less hysteresis loss in the steel core than there would be for one or three aluminium layers where the magnetic field does not cancel out.

The hysteresis effect is negligible on ACSR conductors with even numbers of aluminium layers and so it is not considered in these cases. For ACSR conductors with an odd number of aluminium layers however, a magnetization factor is used to accurately calculate the AC resistance. The correction method for single-layer ACSR is different than that used for three-layer conductors. Due to applying the magnetization factor, a conductor with an odd number of layers has an AC resistance slightly higher than an equivalent conductor with an even number of layers.

Due to higher hysteresis losses in the steel and associated heating of the core, an odd-layer design will have a lower ampacity rating (up to a 10% de-rate) than an equivalent even-layer design.

All standard ACSR conductors smaller than Partridge (135.2 mm2 {266.8 kcmil} 26/7 Aluminium/Steel) have only one layer due to their small diameters so the hysteresis losses cannot be avoided.


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