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Arcflash Reduction Maintenance System

Arcflash Reduction Maintenance System
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Arcflash Reduction Maintenance System - 1

What is an Arcflash Reduction Maintenance System™ unit? A circuit breaker equipped with an Arcflash Reduction Maintenance System can improve safety by providing a simple and reliable method to reduce fault clearing time. The Arcflash Reduction Maintenance System unit uses a separate analog trip circuit that provides faster interruption times than the standard (digital) "instantaneous" protection. Work locations downstream of a circuit breaker with an Arcflash Reduction Maintenance System unit can have a significantly lower incident energy level. Benefits of the Arcflash Reduction Maintenance System unit • Increased worker safety—when enabled, the Arcflash Reduction Maintenance System provides an accelerated instantaneous trip to reduce arc flash • The operator can pre-select from five levels of protection to facilitate the maximum arc-flash reduction while avoiding nuisance tripping during planned startup and maintenance operations without disturbing the normal operational trip unit settings • Once the setting for the Arcflash Reduction Maintenance System has been properly chosen, the Arcflash Reduction Maintenance System is enabled by a simple lockable switch that can be incorporated into a lockout/tagout (LOTO) procedure •The lockable switch is mounted on the front door, or remotely, up to 9.78 ft (3m) away from the breaker, eliminating the need to open the door to enable it (no special PPE required) • The Arcflash Reduction Maintenance System is designed to be used only during the time that a worker is exposed to the flash hazard. The Arcflash Reduction Maintenance System is not activated or armed continuously. This feature improves overcurrent coordination when compared to a permanently installed instantaneous trip element on the same circuit breaker •Reduction in incident energy levels may allow reduced levels of PPE to be used, offering an improvement to worker comfort and mobility • When properly applied, the hazard risk category frequently can be lowered one or two categories, permitting less PPE How is the Arcflash Reduction Maintenance System used to reduce incident energy? When the Arcflash Reduction Maintenance System is enabled and fault current is detected, the clearing time of the associated circuit breaker is reduced. The table below shows how incident energy varies with fault duration times where the bolted fault level is 40 kA. Bolted Arcing Fault Incident Hazard Fault Fault Duration Energy Risk Note: Incident energy values shown in this table were calculated using the IEEE® STD 1584TM-2002 method for a 480 Vac system with a working distance of 24 inches. Other parameters are: grounding type = solid grounded and equipment type = switchgear.

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Arcflash Reduction Maintenance System - 2

How is the pickup setting of the Arcflash Reduction Maintenance System chosen? The pickup settings must be chosen by a person who is qualified in power system analysis. The initial setup of each Arcflash Reduction Maintenance System will require power system analysis to determine the fault currents that flow through the circuit breaker associated with the Arcflash Reduction Maintenance System unit. The Arcflash Reduction Maintenance System has five pickup settings that are based on multiples of the per unit secondary current monitored by the trip unit of its associated circuit breaker...

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