There are several trends in the medium and high voltage cable accessory sector just now and they result from a number of drivers. Insulation is becoming more polymer-based with a decreasing use of paper while the mechanical aspect of cable jointing is moving towards bolted connections rather than compression types. Use of heat-shrink accessories is on the increase but cold-shrink is also becoming more popular and a number of people feel this is the technology of the future. But all are agreed that the power industry is still very conservative, so time scales for change are expected to be relatively long. As polymer technology has developed generally, material costs have come down and performance has risen to provide strong competition for paper. PVC-based materials have given way to medium density polyethylene (MDPE) which offers higher resistance to ultra-violet and other natural factors. Fillers can also be added to the polymer to prevent tracking. But polymer materials can be damaged more easily during installation. An accidental cut can run, affecting dielectric strength around the damage and, perhaps, letting in water. But engineers say if two or three layers of paper are damaged, the integrity of the insulation is unlikely to be affected in practice.
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