GB279993A - Improvements in electric transformers - Google Patents

Abstract

279,993. Heyes & Co., Ltd., and Jones, B. E. Sept. 27, 1926. Sparking, preventing.- A transformer is provided with a secondary winding in the form of a detachable plug element connected by flexible leads to the load such as a lamp or motor to be supplied, and a switch adapted to be operated by insertion of the plug is provided in the primary circuit. The primary coils 3, 4 are arranged on a laminated core 5, the magnetic circuit of which is completed when the transformer is in operation by a laminated member 10 carrying the secondary winding, and forming part of a removable plug element 7. In the lower part of the casing 1 there is provided a double pole switch 20 controlling the primary circuit, and the operating member 19 of the switch is arranged to project into a slot 18 in a plunger rod 16 which is urged upwardly to maintain the switch in an open position by a spring 21. Insertion of the plug element displaces the rod 16, as shown, to close the switch. The plug 7 is retained in position by a pin and slot connection with the casing which necessitates turning the plug before disconnection, thereby reducing the load current before the switch opens. A hinged inspection door 25 is interlocked with the switch mechanism by means of a forked bracket 26 which embraces the rod 16 and is slotted to permit the passage of pins 28. These pins serve to prevent opening of the cover when the switch is closed by engaging the bent ovtr ends 27 of the bracket 26. When the switch is in the open position and the cover is opened, closing of the switch is prevented, until the cover is closed, by a forked member 29 which moves forward under the influence of a spring 30 when the bracket 26 is withdrawn and engages under the pins 28, the rod 16 then being in the raised position.