GB217602A - Improvements in and relating to systems of electric ship propulsion - Google Patents

Abstract

217,602. British Thomson-Houston Co., Ltd., (Assignees of Rask, L.). June 14, 1923, [Convention date]. Exciting; alternating-current induction machines.-In an electric ship propulsion system a number of generators are arranged to supply a greater number of motors each driving a propeller shaft, and in a triple screw ship the middle propeller is arranged to run at the mean speed of the outboard propellers when these are running at different speeds. A generator 3 supplies power to a single-fed induction motor 5 through a switch 8, forward running switches 10, 11 and polechanging switches 13 or 14, switch 13 giving 24 poles and switch 14 giving 16 poles. A second generator 4 similarly supplies a motor 6 through switches 20, 22 and 24 or 25. In both cases reverse motion is obtained through switch 9 instead of 11 and switch 21 instead of 22. The middle motor 7 of the double-fed type has its stator 17 supplied from the generator 3 through a switch 16, which is operated with the switch 11, and its rotor 29 is connected through a switch 27, which is operated with the switch 22, and the switch 25 to the generator 4. When the motor 6 is running at slow speed, the secondary 29 is shortcircuited through part of switch 24. During reverse running, the motor 7 is inoperative. The various switches are operated by reversing controllers 12, 23 and pole-changing 'controllers 15, 26 and each reversing controller may be mechanically interlocked with its pole-changing controller so as to prevent reversal in the high speed motion. The switches 13, 14, 24 and 25 may be controlled by a cam-shaft. In a modification switches are provided for short-circuiting both or either the rotor and stator of the motor 7.