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Supplied to our customers since 1986, one of the most enduring and familiar of RWW Engineering’s MV products is the 22/33kV outdoor circuit breaker. Affectionately referred to as ‘The Dogbox’, this unit essentially comprises an indoor (fixed) 630A or 1250A 22kV circuit breaker within a mild or stainless steel enclosure.

External circuit connections are effected via roof mounted bushings. Its appeal lies in the fact that it can be configured to include CTs and VTs within the enclosure, thereby eliminating the need to install external outdoor CTs and VTs.

This feature helps minimise switchyard space requirements and reduce site installation costs. A generously sized LV controls compartment is provided with a pad lockable hinged door affording access to the CB controls and LV field wiring connections. The unit currently utilises the Merlin Gerin type SF1 (SF6 ) circuit breaker. Other circuit breakers can be used in custom applications.

The RWW outdoor ‘Dogbox’ circuit breaker is available in the following ratings:

  • 11 kV 630/1250 A 25 kA 95 kV BIL
  • 22 kV 630/1250 A 25 kA 150 kV BIL
  • 36 kV 630/1250 A 25 kA 170 kV BIL
  • Mild steel or 3CR12 option
  • Protection relays, metering instruments; current and voltage transformers can be housed in the cubicle.
  • Developed and manufactured in the Republic of South Africa

The Merlin Gerin type SF1 (SF6) circuit breaker range of comprehensive and proven three-pole circuit breaker units for indoor installation using SF6 technology. Both compact and dependable, it is ideally suited to the most demanding applications.This circuit breaker range meets IEC standard 62271-100.

These circuit breakers are mainly used for switching and protection of networks from 12 to 36 kV in primary and secondary power distribution. The auto compression breaking technique used in these circuit breakers means that making or breaking all types of compacitive or inductive currents can be achieved without dangerous overvoltages for the switchgear connected to the network.

SF range circuit breakers are particularly well suited to switching and protection of capacitor banks; they are classed C2 according to standard IEC 62271-100.

Additional tests have been carried out: please consult us.