Distributed IO can reduce arc flash hazards

Causing thousands of injuries every year, arc flash is a serious and even deadly hazard, which makes selecting the right safety solution critical.

11/10/2012


Courtesy: TURCKIndustries are becoming more communication-centric, requiring dependable enterprise connectivity to collect and distribute production data. Consequently, protecting control equipment is critical. Consequently, electrical enclosures are an essential part of any installation. While enclosures do protect against exposure to the elements, they can also present a serious arc flash hazard, as accessing energized distributed I/O equipment housed inside the enclosure poses the threat of an arc flash—an explosive blast of flame, debris, sound, and force—every time the enclosure is opened.

An arc flash can occur anywhere in an electrical system and is caused by a phase-to-phase fault or when the electrical service is provided a low impedance path to ground, or phase-to-ground fault—the severity of which is determined by the distance from the arc and the amount of energy available. This blast usually lasts under one second but can reach up to 35,000 F, which can result in severe burns to human skin. Additionally, the arc flash blast can propel molten metal, shrapnel, and tools through the air, causing a serious risk to facility personnel and occupants.

The gravity of this danger requires plant managers to be proactive in selecting the ideal safety solution that protects employees without impeding productivity or equipment accessibility. Therefore, when it comes to safeguarding against arc flash hazards, plant managers need to think outside the box to prevent injuries while increasing visibility over control equipment and improving productivity. While solutions exist that can reduce the risk of injury when accessing controls, distributed I/O mounted outside the enclosure ensures continued, reliable connectivity without putting employees in harm’s way. 

Safety outside the box

While no solution can completely eliminate the risk of arc flash hazards, there are solutions that minimize engineers’, technicians’, and maintenance workers’ exposure to such risks. Since there is a potential for an arc flash occurrence every time the electrical enclosure is opened, being able to take distributed I/O equipment out of the electrical enclosure, which may contain live voltage with sufficient energy for an arc flash event, and mount it in the field, minimizes risk exposure and ensures continued connectivity. 

Further, engineers and maintenance workers often require frequent access to distributed I/O equipment and controls to maintain continued production, so using an efficient, safe method for personnel interaction is crucial. Mounting equipment and controls outside the electrical enclosure provides engineers with easy and immediate access to it without opening the enclosure. This not only ensures the same level of connectivity and communication, but also enhances operator safety.

For additional communication flexibility, distributed I/O products are engineered for durability, allowing installation in a wide range of demanding plant environments. Featuring IP ratings, such as IP65, IP67, IP68 and IP69K, these products can reliably perform in dusty, wet, and harsh environments without risk of element ingress. Some distributed I/O solutions can even withstand heavy washdown conditions and total submersion.

This inherent durability allows distributed I/O products to be effectively removed from the electrical enclosure and exposed to the application environment without malfunctioning, causing network faults, service interruptions, or arc flash ignition. 

Conclusion 

Causing thousands of injuries every year, arc flash is a serious and even deadly hazard, which makes selecting the right safety solution critical. Distributed I/O not only provides high-level visibility of production data and enterprise connectivity with in-the-field convenience, it also simultaneously reduces the risk of arc flash ignition and improves process efficiency. 

Randy Durick is director of the network and interface division of TURCK.



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