GB246943A - Improvements relating to vapour electric rectifying apparatus - Google Patents

Abstract

246,943. Rowbotham, J. L., and Hewittic Electric Co., Ltd. Nov. 19, 1924. Vapour apparatus, arrangements of.-In vapour electric rectifying apparatus comprising a group of rectifiers arranged to work in parallel, automatic means are provided for bringing additional units into operation in succession as the direct current load increases or in the event of failure of one or more of the operative rectifiers, and for cutting out the units in succession as the load decreases. In the arrangement shown the trausformers 7, 8, 9 feeding three rectifier units comprising pairs of rectifiers 1 - - 6 are adapted to be connected to the alternating current bus-bars 10 by switches 11, 12, 13 provided with closing coils 24 and trip coils 25. The apparatus is started by closure of a switch 30, which may be time controlled, thus completing the circuit of a coil 31 connected to direct current bus-bars 23. This causes a resistance 34, normally short circuited at the contacts 33, to be introduced into the circuit of a coil 35, normally holding open a time lag switch 37, which now closes to complete the circuit of a coil 45 which in turn energizes the closing coil 24 of the switch 11 by closing the contacts 47. The removal of the short circuit from the resistance 34 also de-energizes a coil 48 which causes a switch 50 to open and introduce a resistance 51 into the circuit of the winding of a time lag switch 52 adapted to bring into operation the rectifiers 5, 6. When, however, the rectifiers 1, 2 have been rendered operative, the circuit of relays 29 controlled by coils 28 is completed thus restoring the short circuit on the resistance 34 thereby de-energizing the winding 24 and also arresting the operation of the time lag switches 52, 56. The rectifiers now supply current to the busbars 15 which are adapted to be connected to the main direct current bus-bars through a circuitbreaker 22. If, however, the rectifiers 1, 2 fail to become properly operative, the circuit of the relays 29 remains open and the time lag switch 52 is permitted to close to bring into operation the rectifiers 3, 4. Also in the event of the load exceeding the capacity of the rectifiers 1, 2, the coils 16 open the contacts 59 thus removing the short circuit on the resistance 51 and causing rectifiers 3, 4 to be brought into operation. Similarly, if the load exceeds the capacity of the rectifiers 1 - - 4 the short circuit on the resistance 55 is removed by relays 60, and mectifiers 5, 6 are brought into operation. The means for cutting out the units in succession as the load decreases comprises relays 20, 18 adapted to break, at the appropriate load values, the circuits of holding off coils of time lag switches 63, 65 which are adapted to complete the circuits of the trip coils 25 of the transformer switches 13, 12.