As an electrical contractor or power distribution manager in a workplace environment, you’ll know the importance of safe, continuous, uninterrupted power distribution. You’ll know that the working principle of a contactor is similar to that of a relay but with a higher current rating. But where can you source contactor items and ancillary equipment which lives up to the demands of power distribution circuits in a modern workplace?
Wherever and whenever you need to get the best from the equipment which is in your charge, be they electric motors, thermal evaporators, lighting, capacitor banks or heating systems, rapid enhanced performance of the switch is crucial. There is a tendency for damage to occur as the contacts are opening and/or closing. As the contacts open and close the danger of arcing is ever present. The faster the contacts separate or connect, the less likelihood there is of arcing.
According to the RS components website from which much of this article research is drawn, contactors and the control systems in which they are designed to operate require perfect integration. For maximum efficiency and safety one such contactor which is designed for simple, rapid integration is the Schneider Electric TeSys D 3 pole design.
In modern contactors there is what is known as a tipping point mechanism which ensures a rapid opening/closing action every time. However, as with every upside there is a down side and that is no less true of electrical contactors. The downside of the processes of rapid opening and closing is, as you are probably well aware, a phenomenon known as ‘contact bounce’.
Unwanted open-close cycles
Contact bounce can cause additional and unwanted open-close cycles. If this happens the danger of arcing is exponentially increased. One solution to this issue is to have bifurcated contacts. This is a system where two contacts are designed to open and/or close simultaneously, but with an almost imperceptible time lag so the bounce is at slightly different times. This system ensures that the circuit disconnection is not an issue and arcing is avoided.
If arcing does occur in an electrical contactor this may have potentially explosive repercussions. Electrical circuits are designed to work in specific environments and are in the main sealed from the ambient environment. This is especially true where there is the potential for explosive or flammable gases or substances to compromise the interior of the system.
Although there is typically fail-safes built in to the design and operation of electrical systems, reduction of the potential risk is one benefit of bifurcated contacts. Another tried and trusted technique for improving the life (and overall safety function) of contactors is contact wipe. This involves a design where the contacts move past each other after initial contact, and in so doing will wipe off any contamination which would otherwise remain on the contacts points.
Electrical contractors and/or plant and power distribution managers requiring further information can check out the commercial contactors info available at RS for suitability and end application in relevant processes. Differing demands on equipment from industry to industry means a tailor made solution is the best way to fit the end process.
KW: contactors available at RS
Image credit: Freedigitalphotos.net – Dan
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