Power losses in underground cables cause temperature rise of the cables during their operation, there are two types of a power losses generated in the cables: current dependent powers and voltage dependent powers. Current dependent powers refer to the heat generated in metallic cable components (conductors, sheaths etc.); voltage dependent powers refer to the powers in cable insulation . Sheath losses are current dependent and their values in single-core underground power cables cannot be disregarded as they, in some cases, could be greater than power losses in the conductors. Sheath losses in single-core cables depend on a number of factors, these factors are:
TopTwo types of cable layouts formation usually used in practice are studied in this chapter:
- 1.
A trefoil arrangement of three single-core cables, where the cables are laid as at the corners of an equilateral triangle. In this formation two single-core cables are laid close together with one cable forming an upward apex, (Figure 1a).
- 2.
A flat arrangement of three single-core cables, where the three cables are laid in the same horizontal plane with the middle cable equidistant from two outer cables, (Figure 1b).
Figure 1. Single-core cable layouts (a) Trefoil formation (b) Flat formation
More details of power cables installation, ratings and laying are reported by Halperin, H., & Miller, K. W. (1929). Buller, F. H. (1949), Thue, W. A. (2003), IEEE Std. 575. (1988), British Standard BS 7430. (1998), King, S.Y., & Halfter, N.A. (1982), Anders, G. J. (2005). Riba, J. R., Ruiz, X., Alabern, M. (2006). Ma, H., Song, J., Ni X., & Zhang, L. (2008) and IEC Standard 60287. (2001).
Top10.2 Mathematical Algorithm
The single-core cables components are shown in (Figure 2).
Figure 2. Unarmored single-core cable components