Improvements relating to signalling transformer apparatus for use in dangerous atmospheres

摘要

692,625. Transformers. DAVIS & SON DERBY, Ltd., J., and DAVIS, W. H. Oct. 10, 1951 [July 10, 1950], No. 17144/50. Class 38 (ii). [Also in Group XXXVII] In an apparatus comprising a signalling transformer and its control switch in separate compartments of a flame-proof enclosure, the switch operating lever 20 is arranged to actuate locking means such that the cover 10, 11 of neither compartment 12, 13 can be removed whilst the switch is "on." The lever 20 is secured to a spindle 21 carried by an extension 10a of the cover 10 of the transformer compartment, the spindle 21 having projections 21a which engage in correspondingly-shaped recesses in the operating spindle 23. When the switch is " on," the projections 21a abut the sides of a slot 24a in a locking plate 24 on the cover 11 and prevent the removal of the cover 10. The switch-operating arm 25 secured to the spindle 23 has parts 26, 27 which abut flanges 29 when the switch is " on " and prevent removal of the switch cover 11 and the cover 10 as a unit. Dowels 30 prevent sideways displacement when removing the covers after unscrewing bolts 33. An insulating plate 32 may be provided below the switch cover 11.