Distribution of the electric force in the size of the mine galleries

摘要

305,221. Siemens - Schuckertwerke Akt-Ges. Feb. 3, 1928, [Convention date]. Installation conductor arrangements; protective arrangements. - Electrical energy is supplied at the working face of mines and the like by a main cable which is laid at the working face and to which apparatus is connected through short branch cables, the main cable being capable of disconnection at a gallery switch. The main cable 16 is divided into lengths which may be connected together by plugs and sockets 20 and by branch plugs 21 to which the branch cables leading to the machines 23 are connected. The main cable is connected to the mains 11 through a gallery switch 12 which comprises overload releases 13 and a voltage release 14. The circuit of the latter is fed through a transformer 15 and includes an auxiliary conductor 17 and earth conductor 19 comprised in the main cable. The branch plugs 21 include overhead releases 24 and a voltage release 25 the contacts of which are in the circuit of the gallery voltage release 14. 'The circuit of each voltage release 25 is completed through auxiliary conductors in the branch cable and the casing of the motor or machine switch. The contacts 27 of the voltage release are normally controlled so that the whole system at the working face may be rendered dead from any branch plug, and they may also be held closed by mechanical locks until the circuit is re-established when resumed operation is desired. Reference has been directed by the Comptroller to Specification 285,182, [Class 38 (v), Electric switches &c.].