| 摘要 |
PURPOSE:To enable a prevention from the pressure rise in the board to a prescribed level, by means of enclosing a relief port, which is partially provided in the enclosed switchboard, with a relief board that is formed in a manner with its one end swingably fixed and its another end slidably constructed. CONSTITUTION:A relief opening 3, provided in the ceiling part 2 of an enclosed switchboard 1, is enclosed by a relief board 5. One end of said relief board 5 is swingably supported by a pin with hinges 4 used, and another end is fixed by a retainer plate 7. The retainer plate 7 comprises a mounting unit 7a to the ceiling part 2 and a pressing unit 7b for pressing the relief board 5, with the mounting unit 7a fixed by a bolt 6 to the ceiling part 2 and the pressing part 7b slidably pressing to retain an end edge of the relief board 5 from upward. In such constitution, an uprising of pressure within the board expands the relief board 5 to outward of the board, and the relif board 5, if the part pressed by the retainer plate 7 goes excessively backward from a lap dimension H, is made opening to release the internal pressure. |
