IC-OCT-NOV22-PG32+33_Layout 1 10/11/2022 16:15 Page 32
ELECTRICAL SAFETY
Mitigating arc flash events in process heating applications
Medium or high voltage equipment for industrial applications always carries certain safety risks. arc flash events are a prime example of a rare, but potentially fatal, situation that can be mitigated with the right technology. as electric process heaters become a popular alternative for larger applications that have historically favored gas-fired heaters, it is vital to consider how they incorporate arc flash mitigation features. here, Dennis long, chief system designer for energy and environmental technologies business unit at industrial heating technology manufacturer Watlow, shares insight into why arc flashes happen and how manufacturers can mitigate their risk.
C 32 octoBer/noveMBer 2022 | inDustrial coMpliance
oncerns about decarbonisation, automation and safety have driven many organisations to replace gas fired heaters with larger electrical alternatives. As medium voltage process heaters are relatively novel to many applications, they represent a potential new source of risk that manufacturers must recognise.
Potential risks
An arc flash is an electrical explosion that occurs when there is a short circuit in a system, which can be caused by a build-up of corrosion or conductive dust. If the voltage is high enough, and if there is a path to ground or a lower voltage, the resistance of the air is overcome and results in an arc. Arc flash events can result in significant damage. As the energy
release increases, the risk of fire and injury rises with it. If the energy release is high enough, molten conductor metal and high- pressure plasma energy that can escape from the cabinet, posing a risk to anyone in the vicinity. The potential arc flash energy is determined by several factors
including equipment voltage, available current and the duration of the event. While it may be practical to reduce the potential arc flash energy while limiting voltage or current, overall project cost can make this difficult. Although arc flash incidents are rare, their potential for damage, injury and death makes them a great concern. Some estimates put the incidence of arc flash events between five to ten per day worldwide.
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