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Arc Flash Management
Comparison between arc-resistant cabinets and arc-mitigation technologies
manufacturers of these heaters must be aware of that risk . On top of that , many applications use arrays of large megawatt heaters , connected to multiple panels . This drives the need for a solution that can isolate the specific panel ( s ) where arc flash occurs , isolating faults from the main breaker / feeder where possible . On the other hand , arc flash events are well understood , as are the strategies for reducing their effects . An understanding of these strategies should be “ built in ” to any technology for process heating .
Reducing the effects of an arc flash event Generally speaking , there are three main strategies for reducing the effects of any potential arc flashes that could occur with a piece of equipment : 1 . Increasing the distance from the potential source of an event 2 . Reducing the available fault current 3 . Decreasing the duration of the event ( i . e ., how long the arc itself exists )
Ideally , all could be used in combination to ensure maximum safety , but this is often not practical when considering overall project cost . That said , the duration of the event is the most practical influencer to reduce and has the largest impact on the total amount of energy released . Reducing the overall fault clearing time is often the best , most direct way to reduce arc flash hazards . This point can be illustrated through a comparison between two current approaches to limiting the damage wrought by arc flashes : Arc-resistant cabinets and arc mitigation technologies . Mitigation technologies make more sense economically and from a safety perspective , and thus should be incorporated into designs for and around medium voltage process heaters and similar equipment .
Arc-resistant cabinets The idea behind an arc-resistant cabinet is to reduce exposure to arc events by encasing the system in a metal-clad cabinet with a venting system . Typically , the doors of the cabinet are the point of failure in an arc event : Rapidly heated air expands and builds up pressure inside the cabinet , eventually causing the doors to blow open and exposing those nearby to heat and blast . With an arc-resistant cabinet , the flash energy ( more precisely , the heated gas and pressure ) is redirected through a duct near the top of the cabinet . When the doors are closed and all covers are installed correctly , arc-resistant cabinets reduce the energy to which people and other pieces of equipment are exposed . That said , arc resistance does not actually limit the energy from the event itself — it merely redirects it . There can still be substantial damage to the system itself , as well as significant risk . But perhaps the greatest drawback is the fact that the system must be closed for the arc-resistant cabinet to work ; it will not work , for example , with the doors open . This is a problem , as many arc events occur during maintenance , precisely when the doors are open . An arcresistant cabinet will not afford any additional protection in these cases . Of course , there are other issues as well : The size and weight of the cabinet , the certification needed ( ANSI C37.20.7 ), and , naturally , the overall cost .
WATLOW ' s OPTIMAX ® electric heat exchanger
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Long , Dennis and Roly Juliano ( 2022 ). “ Electrification and Medium Voltage Process Heaters Systems .” White paper , https :// de . watlow . com / blog / posts / electrification-and-medium-voltage-process-heater-systems .
www . heat-exchanger-world . com Heat Exchanger World November 2022
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