Ventilation system for arc-resistant switchgear enclosure

A ventilation system for an arc-resistant enclosure for electrical components, said arc-resistant enclosure comprising:

• a plurality of compartments for housing said electrical components, each of said compartments housing one or more of said electrical components, said plurality of compartments being arranged to form an internal arc chamber for providing a path for releasing from said enclosure pressure and hot gases produced by an electrical arc fault associated with an electrical component in a least one of said compartments;
• each of said compartments having an aperture for permitting pressure and gases to flow therefrom into said arc chamber and having hinged covering means for each of said apertures;
• said hinged covering means covering the aperture with which it is associated during both normal operation and when an arc fault occurs in a compartment with which it is not associated and, upon the occurrence of an arc fault within one or more of said compartments, uncovering the aperture of a compartment in which an arc fault occurs to permit pressure and gases to flow from a compartment in which an arc fault occurs into said arc chamber;
• said arc chamber comprising a first vertical section providing an exit path to the top of said enclosure;
• and, a second horizontal section for permitting a portion of said arc chamber to be disposed beneath at least one of said compartments, said second horizontal section adjoining and communicating with said first vertical section,
• the arrangement being such that pressure and hot gases produced within a compartment within which an electrical arc fault occurs are controllably released from the top of said enclosure and prevented from entering into a compartment in which an arc fault has not occurred,
• said ventilation system comprising:
• vent means comprising a plurality of ventilation slots disposed in at least one of said covering means and a plurality of pivotable vent flaps mounted on said at least one covering means for covering and uncovering said slots, said slots permitting convection cooling within at least one of said compartments whereby heated air can flow between said at least one compartment and said arc chamber when said vent flaps uncover said slots, said flaps, when covering said slots, preventing pressure and hot gases to flow from said arc chamber into said at least one compartment.