An instantaneously available reserve power plant particularly for use with telecommunication plants

摘要

771,226. Standby supply systems; dynamoelectric machines. ALLMANNA SVENSKA ELEKTRISKA AKTIEBOLAGET. Oct. 27, 1955 [Nov. 3, 1954], No. 30723/55. Classes 35 and 38 (4). A reserve power plant coming into operation on failure of the main supply comprises a selfexcited D.C. machine 1 having a flywheel 19 and a set of polyphase rotating brushes 5 connected to the load bus-bars 10 through sliprings 8 and switch 9. The brushes 5 are rotated at constant speed by an electric motor 7 which is fed from the bus-bars 10 and maintained at constant speed by a circuit not shown. On failure of the normal supply main 11, switch 12 opens and power is momentarily derived from the machine 1, a voltage regulator being employed to counteract the effect of the machine slowing down. Meanwhile the engine 13 is started and then generator 14 is connected by switch 16 to drive the bushes 5 through motor 7. When the voltage appearing at the rotating brushes is in phase with the voltage of generator 14, the switch 15 closes to enable the generator to feed the load. The same process happens, in reverse, to reinstate the supply from mains 11. If desired, the machine may have armature slip-rings connected to the mains by a switch 17, and by the insertion of an inductance between the mains and the machine, the voltage supplied to the load may be modified by altering the excitation of the machine. Instead of having a separate motor 7, the brushes and a flywheel may be driven from the machine 1 through a free-wheel.