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Changing regs highlight decontactor benefits

Stephen Thackray of Marechal Electrical discusses the new European standards that affect industrial plugs and sockets

Over the years, the old British Standard BS 4343 for industrial plugs and sockets became synonymous with a certain type of system - in much the same way as 'hoovering' became a regular household chore. However, as Mr Dyson proved, consumer preconceptions on vacuuming can be changed when something patently better is developed.

A similar transformation has taken place in the world of industrial plugs and sockets. The obsolete BS 4343 standard, which catered for only one design of electrical contact (pin and sleeve), has been replaced by three standards which better acknowledge the fact that other (and probably better) contact designs are available.

The first part of the replacement Euro standard BSEN60309-1 is obligatory for all manufacturers of industrial plugs and sockets, and therefore to buyers and specifiers too. It is worth noting that it sets down the minimum level of performance for a plug and socket.

The second part - BS EN 60309-2 - is an optional standard that only concerns manufacturers who use a pin and sleeve contact design and then want their particular brand to inter-mate with similar designs of other manufacturers, i.e. it is not mandatory and is solely an interface dimensional standard.

BS EN 60309-4 addresses switched socket-outlets and connectors with or without interlock and the parameters they must meet.

The revision of this standard highlighted the benefits of the decontactor, which is, basically, an industrial plug and socket, switch-and-isolator-in-one. It employs contact technology similar to that used by the circuit breaker and provides a simple way of connecting and disconnecting fixed and portable single, three-phase and star-delta equipment. It offers on-load make and break performance. There is no need for a separate isolator and the IP66/IP67 versions offer automatic ingress protection without having to turn sealing rings.

A decontactor can help increase safety in several ways.

  • Unplugged equipment is visibly isolated, unlike an isolator.
  • Fitters can disconnect a pump or motor without opening a terminal box – which in many cases may be some distance away from the equipment to be worked on.
  • Equipment can be stopped at the press of a button in an emergency – an action that will instantly cause the plug to eject from the socket.

Maintenance costs are also minimised, because in the event of an equipment breakdown, only a fitter needs to be sent instead of a fitter and an electrician. Pre-plugged standby equipment can be exchanged in minutes and changing individual items of equipment does not disrupt a complete assembly line.

A decontactor combines the performance of a plug and socket to EN60309-1 with that of an air-break switch to EN 60947-3 AC-22 and AC-23, and easily exceeds the performance requirements of the old BS4343 standard.

A decontactor also allows for up to 24 positions for voltage discrimination and enables sockets of similar voltages to be non-interchangeable too. This offers the additional bonus that from just one socket outlet, a variety of supplies – single phase, three phase, TPN etc - can be drawn with complete safety.

A decontactor uses butt contact technology, which can offer a variety of opportunities and benefits for the end-user. The contact design allows load-breaking and making, and is inherently safe, being capable of breaking 10 times its nominal current in an emergency at the press of a button. The socket is therefore also an integral switch, yet it remains much smaller than other designs. This allows your customers to install more sockets on the same panel, as they have a smaller foot-print/wall-print in a confined area, and less exposure to damage. Further, spring-loaded butt contacts cannot 'freeze' after extended periods of non-use.

The plug cannot be withdrawn on load. The original decontactor design was, in fact, inspired by a French engineer who had experienced, first hand, the danger from such an action. The only way to release the plug from its socket is to press the socket latch.

The decontactor is a connection problem-solver for engineers looking for solutions. It is flexible, offering auxiliary contacts and products rated up to 250A.

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