6.1 Introduction

The first rule to understand when considering the design of high voltage cables is that many of the design parameters are set by the system into which the cable will be incorporated. The designer must take a humble stance of respecting, for example, the circuit current rating and impulse withstand voltage of any overhead line to which the cable may be connected. Apart from such technical aspects there is the impact on cable design of the economics of manufacture, in-service running costs, reliability, service-ability and the ever-increasing influence of environmental concerns.

The expectation of an insulated high voltage cable is that it will be an entirely passive element in the power transmission system, nonperturbing to associated equipment and providing unremarked service for many (at least four) decades. This life expectation has arisen because previous generations of cables have already provided such service and, understandably, the customers for cables see no reason to accept a lesser performance. However, the incidence of faults of the British 275 and 400 kV transmission network due to insulated cables is a small proportion of the overall number of system faults. At medium voltage levels, cable failures are due principally to third party damage [1].

The design of cables is to a large extent regulated by a number of industry, national and international standards and guides. These may be related to voltage level, technology of production or customer preference. Table 6.1 shows how the technology of manufacture, and in particular the primary...