Arc Resistant Low Voltage Metal-Enclosed Switchgear


Siemens arc resistant Type WL low voltage switchgear provides an added degree of protection over standard metal-enclosed switchgear. In addition to bolted faults, Siemens Type WL low voltage switchgear is designed and performance tested to ANSI/IEEE C37.20.7 to provide protection from the hazards of internal arcing faults.


Siemens now offers arc resistant, metal-enclosed, low voltage switchgear designed to provide an additional degree of protection for personnel performing normal operating duties in proximity to the energized equipment.  Such duties include opening or closing breakers, closed door breaker racking, reading instruments, or other activities that do not require cover removal or opening doors (other than auxiliary/instrument doors).

An internal arcing fault can be caused by insulation degradation, insulation contamination, entrance of vermin, foreign objects coming into contact with the energized bus, or any other unplanned condition that creates an electrical discharge path through air.  During an arcing fault, the voltage at the fault location is essentially the system voltage and fault energy is focused within the switchgear enclosure.  Arc temperatures can exceed 20,000 degrees Kelvin, rapidly heating the air and vaporizing metal parts.  The expanding plasma creates severe mechanical and thermal stress in the equipment which can blow open door and covers and through or fragments the enclosure. 

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