Arc Flash Safety 1, 2, 3

Dec. 13, 2012
Industrial network equipment must frequently have its data be monitored and extracted, which requires frequent access to the equipment.

Electrical enclosures safeguard both the energized equipment within them and the people who work around them, but they also pose a risk for igniting an arc flash incident every time they are opened. An arc flash is an explosive blast of flame, debris, sound and force—the severity of which is determined by the distance from the arc and the amount of energy available. Knowing and understanding the arc flash risk and available safety solutions, along with their strength and limitations, enables facility managers to select and implement a safeguard that delivers the necessary level of protection while simultaneously meeting productivity and efficiency goals.

1. Flame-resistant apparel. Made from fabrics that resist ignition, flame-resistant apparel is designed to protect workers in designated areas where intermittent exposure to flame or heat is possible. Normal fabrics, such as cotton and nylon, will burn away from the point of ignition with an increasing rate of flame spread and continue to burn after removal of the ignition source. This makes the wearer extremely vulnerable to injury. Flame-resistant fabrics are engineered to self-extinguish almost immediately upon removal of the ignition source—preventing it from destroying the protective barrier that acts as a shield between the wearer’s body and the flame. Additionally, to accommodate a variety of risk levels, flame-resistant apparel is offered in everything from button-down shirts and jeans to arc flash suits, gloves and boots.

Although flame-resistant apparel will minimize injuries while allowing employees to perform daily functions, it does not actually prevent the occurrence of arc flash or eliminate the possibility of a worker igniting or encountering a blast. When using flame-resistant apparel, it is crucial that users know and adhere to strict laundering and care procedures to prevent the fabrics from losing its flame resistant properties, rendering it an ineffective safety solution. Further, it can be cumbersome, time-consuming and laborious to put on, with the extra time and effort needed to suit-up can slow production, particularly when the risk is high enough that multiple layers of protection are necessary.

2. Data interface ports. Communication or control equipment housed in electrical enclosures typically require frequent access by operators in order to analyze data, modify settings or perform maintenance. If these activities require the enclosure to be opened, the worker can be at risk of igniting an arc flash incident. Data interface ports offer an alternative option to opening the enclosure. By providing an external plug-in, data interface ports enable users to access and interact with equipment inside the electrical enclosure. Through this external port, technicians can directly connect to and interact with control components without needing to open an enclosure.

With data interface ports, operators have an external pass-through port that allows them to monitor performance, change settings and extract data while the enclosure door remains closed. While this solution does allow workers to access and modify control equipment without fire exposure, it does not offer the same level of availability as being able to monitor the equipment in the field. First, specialized panels must be installed that are wired to designated equipment, then users will be able to externally connect to the equipment. This solution does prevent operators from interfacing directly with equipment within, and requires excess equipment and set-up time in order to effectively connect to and manipulate controls. This process can eat away at productivity and increase the time it takes to extract relevant production data.

3. Distributed I/O. 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—which may contain live voltage with sufficient energy for an arc flash event—out of the electrical enclosure, and mount it in the field, minimizes risk exposure and ensues continued connectivity. 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.

Distributed I/O products featuring IP ratings, such as IP65, IP67, IP68 and IP69K, can reliably perform in dusty, wet and harsh environments without fear of element ingress without malfunctioning, causing network faults, service interruptions or arc flash ignition. While these network solutions are able to function reliably outside of protective enclosures, not all communications and control equipment offer the same flexibility and durability. Some energized controls may require housing within electrical enclosures.

>> Edited from content provided by Turck, Pentair Equipment Protection, Hoffman brand and AmeriPride by Renee Robbins Bassett, [email protected], Managing Editor of Automation World.

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