Sf6 Switchgear

Switchgear developments
S E Lane,

FKI Switchgear Division (Whipp & Bourne, Hawker Siddeley Switchgear)
The purpose of this paper is to examine the significant developments in MV and LV switchgear technology over the last few decades and why they are only recently beginning to benefit the users. A recent development now has sufficient field experience to show how through innovative design it has been possible to vastly improve an autoreclosing circuit breaker. The author believes that the same innovative ideas will soon be applied to all types of switchgear. The next generation of military switchgear is likely to be developed for the Electric Warship. Irrespective of which distribution supply is used the next generation of switchgear should benefit from the new technology.

INTRODUCTION Reliability The main application of switchgear is in the protection of circuits against damage caused by faults and the restoration or preservation of supplies to as large a part of the system as possible following a fault. In this function they must add reliability to the system rather than contribute to system problems. Providing fault occurrences are rare then system disruption caused by the switchgear, either for maintenance or operational problems has to be very rare. Hence the main objective of any switchgear development must be to improve the reliability of the switchgear itself as well as its performance as a protective device. 1960’s SWITCHGEAR Oil and air circuit breakers dominate LV and MV switchgear markets. Air circuit breakers Air has been used as the insulator in switchgear across the entire voltage range from miniature circuit breakers at domestic voltage to air-blast circuit breakers at transmission voltages up to 800kV. For the purpose of this paper the term air circuit breaker will be used to describe a three-phase circuit breaker using air at atmospheric pressure as the insulator. Early switches were plain-break which stretched an...

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