GB594238A - Improvements in or relating to electric power systems for ship propulsion and other purposes - Google Patents

Abstract

594,238. Transmitting mechanical power. WESTINGHOUSE ELECTRIC INTERNATIONAL CO. March 2, 1945, No. 5245. Convention date, June 8, 1943. Drawings to Specification. [Class 38 (iv)] Synchronizing.-A system for ship propulsion and other purposes comprises a motor operating as induction motor and synchronous motor and two alternators which are arranged to be synchronized with each other. The system comprises a controller for each generator, a motor controller and a speed controller all operable independently of each other. The motor controller provides three starting positions and one running position for each direction and is associated with an electromagnetic interlock preventing opening of the motor circuit while a generator field is energized. The speed controller provides two starting positions, a range of low-speed positions of induction motor operation and a range of high-speed positions with synchronous motor operation ; over these two ranges speed variation is produced by a mechanical connection of this controller to the governor controls of the prime movers accompanied by suitable variation of the excitation of the generators. A latch is provided which the operator must release to enable the controller to move to induction motor positions after synchronous operation. A mechanical interlock between motor and speed controllers prevents movement of the motor controller unless the speed controller is in a slow speed position and prevents movement of the speed controller if the motor controller is in any of its start positions. After starting and connecting the first generator to bus-bars common to the generators and to the motor, the three position generator controller being in its " run " position, the controller for a second generator is moved from its " off " to its " start " position to energize solenoids, changing the speed setting of the prime movers to reduce their speeds, to short-circuit resistance in the field circuit of the running generator, to connect a resistance across the field winding of the incoming generator and to connect the armature thereof to the bus-bars. By these means the incoming machine runs as an induction motor up to near synchronous speed, whereupon its controller is moved to the " run " position in which the original speed setting of the generators is restored, both field windings are given normal excitation and the generators synchronize. The speed controller is arranged to increase the speed of the prime movers while the motor is going from induction motor to synchronous motor operation.