Improvements in and relating to means for limiting the pressure due to an explosion inside flameproof cases for electrical switchgear and apparatus and the like

摘要

214,346. Renzi, W. de. Jan. 24, 1923. Cases, covers, and lids.- Flame-proof metal casings for electrical apparatus used in mines &c. are arranged so that the explosive gases due to arcing within the case are allowed to escape through restricted spaces between adjacent broad machined flanges on the lid and casing, the gases being cooled below the ignition point before reaching the atmosphere, and excessive stresses within the casing being avoided. The switch casing g has broad flanges g1 co-operating with similar flanges i1 on the cover i, studs h projecting slightly above the surface of the flange g1 to preserve a space j which serves as a gas outlet. Similar flanges c1 on the cover c are spaced apart from flanges on the busbar chamber a by thin washers e threaded on the securing bolts d, so that gas outlets f are formed. Outlets m and s are preserved by washers r and m' between the switch casing and the bus-bar and cable outlets. To prevent ingress of dirt through the spaces so formed, they may be covered with strips t of asbestos &c.