Electric.ie March/April 2020

ELECTRIC.IE • The Magazine & Website for the Irish Electrical Industry • 49 up any change to a waveform that confirms the presence of an electric arc and will only trip if the arc is dangerous. Harmless electric arcs appear frequently during normal electrical operation - in the switches, relays, contactors and motors of the various loads plugged into a circuit. ''To remove any possibility of these normal arcs causing nuisance tripping we had to design algorithms that would distinguish harmful arcs from normal arcs as they occurred and isolate the faulty circuit instantly." Arc Causes Electric arcs can result from localised damaged cable or a poor connection in an electrical circuit. For example, an insecure connection in a socket will generate local heating, carbonising sockets and cable insulation. "This transforms the insulating material into carbon, which acts as a conductor and carries some of the current, creating electric arcs. These arcs cause more burning, which produces more carbon, which conducts more current, which causes more arcs. This cycle will continue until the cable insulation and socket catch fire." Schneider Electrics AFDD arrests this cycle before it can even begin. "It doesn't matter whether the arc is caused by a series failure in a single conductor or a parallel failure between conductors, the AFDD detects arcs arising from very small breakdowns in insulation that cause carbonization." “When current flows through damaged insulation from one conductor to another it causes a short circuit that is too weak to be detected by a circuit breaker. The current, known as the leakage current, travels in arcs to ease its passage through the insulation and the AFDD is designed to detect and isolate this whenever it occurs." Easy Installation "Wiring an AFDD is as easy as installing any DIN mounted protection device. All you need to do is add an AFDD downstream of the MCB or RCBO on each of the circuits you want to protect." While installing an AFDD on every final sub-circuit will offer maximum arc protection, many installation owners will be happy just to have protection on power circuits where the risks and consequences are greater, such as in bedrooms and where old wiring is installed. "Schneider Electric AFDDs protect not just the wiring but also the appliances and sub-boards which can pose even greater risk, particularly for landlords, and it's important you help protect all of your clients from the dangers they may cause." With the publication of IS:10101-202x imminent in which the use of AFDDs will be recommended and cited to IEC/ EN 62606. The recommendation will advise on AFDDs in higher risk environments including sleeping areas, places with irreplaceable artefacts such as museums, and possibly retirement homes. Éirin Madden says AFDDs will complete the protection package in final distribution and, with Schneider Electric's help, are now set to become an everyday part of low voltage wiring in new builds and renovations. What can cause an Arc Fault and how the protection works Schneider Electric Compact and easy to install, AFDDs fit into residential and building electric switchboards, alongside other protective equipment