Optimized conductors for XLPE cables with a large cross-section

Abstract

SUMMARYThe focus of this article is the determination of the AC resistance of cable conductors. A simple routine measurement method to measure the AC resistance of complete cable drums is described. An optimization method based on model-simulations and measured values is provided.

Calculation of the ac to dc resistance ratio of conductive nonmagnetic straight conductors by applying FEM simulations

“…Therefore the conducting electrons tend to flow in the outer layers of the conductor. The irregular current density in the interior of the conductor tends to increase its ac resistance [5] since the effective cross-sectional area is reduced. Fig.…”

“…At high frequencies the current tends to be concentrated towards the outer annulus of the conductor [3] and therefore the ac resistance can be much higher than the direct current (dc) resistance, thus increasing power loss in the conductor [4]. The ac resistance impacts greatly on the current rating of power cables [5], since it is limited by the maximum working temperature, which in turn affects the resistance. The ac resistance is an important performance parameter for the optimal design of any power cable [6].…”

Multiconductor cell analysis of skin effect in Milliken type cables

“…In this paper the MCA has been suitably adapted for investigating the skin effect in Milliken type (M-type) cables. As well known, the ampacity of cables with great cross-sectional area can be seriously reduced, at power frequency, by the skin and proximity effects: numerous contributions [5][6][7][8][9][10][11][12][13][14][15][16][17], appeared in the technical literature after that of Lord Kelvin (1873), have allowed studying in depth the experimental and theoretical features of this problem. On this topic, a Cigré WG has delivered a technical brochure [5] about large cross-sections, advertising that [6] "there is no agreed method to define the value of the a.c. resistance to take into account when calculating the ampacity of such cables, whereas it is a critical parameter".…”

“…It is worth remembering that a note in the IEC 60287-1-1 states that the values given apply to conductors having four segments and sectional areas less than 1600 mm 2 . In order to overcome these limitations, since large cross-sections up to 2500 mm 2 are currently used, some techniques of measuring the a.c. resistances in different experimental conditions have been developed [12,15]. This paper develops a meaningful throughout analysis of the skin effect in M-type cables by assuming the idealized circuit of Fig.…”