GB207005A - Improvements in electrical ship propulsion systems and in control apparatus therefor - Google Patents

Abstract

207,005. Miller, L., Campbell, J. P., and Metropolitan-Vickers Electrical Co., Ltd. Oct. 25, 1922. Controllers, actuating - mechanism; master control systems; systems for controlling continuouscurrent motors.-In ship-propulsion sets comprising direct-current motors supplied by engine-driven generators with variable excitation, a main controlling handle by continuous movement from a zero position effects successively the connections of the motor and generator fields to their exciting circuit and also the variation of the generator field strength. The arrangement shown diagrammatically in Fig. 1 comprises two sets, for port and starboard propellers respectively, each set consisting of one motor 3, two generators 7, 8 in series with the motor in a closed ring, and an auxiliary exciting generator 16. In the operation of starting the set, isolating and reversing switches 22, 23 for connecting the motor field 5 to the exciter, switches 20 for connecting the generator fields 9, and a rheostat 25 for varying the excitation of the generator are actuated in succession by a handwheel 33, Figs. 2 and 3, either through pneumatic, linkage, or relay transmission. With relay transmission, the switches may be made subject. to master controllers both in the engine room and on the bridge. A similar handle 34 actuates the switches of the other power set and mechanism for clutching the handles together is connected through links 51, 50 to a switch 27 whereby the power circuit of the two sets are tied together when required. The rate at which the starting operation can proceed may be moderated either by air dash-pots or by reduction gearing. Additional control handles 36 actuate rheostats to vary the motor fields. Interlocked isolating switches are provided for the separate machines. Cubicles with interlocked doors contain the various switches. The smooth working of the plant is further secured by automatically controlling the field of the generators by reverse current relays having their windings connected in the power circuit, by governor-operated switches working at high and low speeds, and by the insertion of braking resistances in the motor-generator ring at suitable times. In a modified arrangement, the generator fields are varied by potentiometer rheostats, and in the starting sequence of operations the motor field rheostats are actuated from the main control handles up to a position in which they are left free to be actuated by their own handles independently of the main control handles. One mechanism for effecting this, shown in Fig. 10, comprises a nut 125 travelling along a screwed part of the shaft 105 of the hand-wheel 33 and having a double cam groove 115 in which slides a pin on the end of a pivoted arm 118 adapted to transmit a limited angular movement through gearing 122, 123 to the motor rheostat shaft 124. Widened portions 125 of the groove 115 allow freedom of movement to the arm 118 when the nut has travelled over the requisite distance in either direction. By means of gearing 106, 110 the hand-wheel 33 actuates the generator field-connecting switches and rheostat in timed relation to the motor reheostat. Alternatively, the switches may be actuated by pneumatic cylinders having valves operated directly or through electromagnets from the hand-wheel shaft, the motor rheostat having two actuating cylinders subject to the two control handles.