NEW TECHNOLOGY REDUCES COST AND IMPROVES PERFORMANCE

Power System Protection presents a multifaceted challenge to the engineer. Protection equipment is associated with extreme voltages and currents and a generally hostile environment for electronic equipment prevails. While the task of the protection system, minimise damage, is elementary, the implementation sets great challenges. Historically protection technology developed in step with the electrical industry, always providing the appropriate tool to do the job. A brief analysis of the electricity supply industry in the industrialised world in the period from 1960 up to 1980 reveals that the security of supply and protection performance was acceptable. The driving force towards electronic and numerical protection came from the manufacturers. This drive to innovate products and to develop new protection relays was not primarily to improve the core protection function in the relays. Cost reduction, innovative communication features and improved information processing were at the forefront of new developments. The customer can however derive a direct benefit to his protection performance from these apparently only cosmetic enhancements. This shift, that occurred with the advent of microprocessor based protection devices, to provide not only the primary protection, but also to facilitate a wide range of supplementary functions took some time to gain acceptance in the conservative protection environment. How important these non core functions of the protection device are, most users only realise with growing experience. The international trend to privatisation has led to a shift in focus from technology to cost. Most of the electrical supply industry is affected by this. Not even the traditionally conservative protection business was spared this process. The justification for protection expenditure to management is difficult, because it does not directly contribute to the sale of electricity, on the contrary, when it operates, customers are often left without electricity. The return on investment in the case of protection is therefore directly linked to the availability of the plant it protects. In this light, a protection system must be selected by evaluating the classic protection performance, the availability and the information transparency. The cost definition of equipment must be extended to include maintenance and life cycle costs. One can summarise the factors that motivate a change,to the new technology as follows[1]: • Service standards with compensation to the customer for poor supply quality. • Fewer qualified staff for commissioning and maintenance. • Large scale refurbishment programs •Technology has moved on and changed the cost/performance picture.