Patent GB-411497-A (GB)
Title: Improvements in or relating to the electrical propulsion of ships
IPC: B63H23/24
Filed: 1932-08-29
Abstract: 411,497. Control of several motors; interlocked controllers. GENERAL ELECTRIC CO., Ltd., Magnet House, Kingsway, London, and COATES, H. J., c/o General Electric Co., Witton, Birmingham. Aug. 29, 1932, No. 24110. [Class 38 (iii).] In an electric ship propulsion arrangement where any one or more of a number of motors may be connected to any one of a number of alternators each of which is provided with control means, mechanical interlocking means are provided such that closure of any selector switch between a motor and an alternator renders the remaining selector switches of that motor inoperative; further the direction switches for each motor, or the means operating them, are interlocked with the control means of the alternator so that the direction switches can be operated only when the control means is in an " off " or equivalent position, and these latter interlocks are rendered effective only between the direction switches of the motor or motors and the control means of that alternator with which the motor is for the time being connected by being made operative or inoperative by the actuation of the selector switches for the motor. The alternator control means desscribed effects control of the speed and of the field of an alternator. The system described comprises four motors and four alternators, four selector or isolating switches being provided for each motor whereby it may be connected to any one of four bus-bars each connected through an isolating switch to an alternator. Each motor and alternator isolator is coupled to a field isolating switch for that motor or alternator. Each motor has a pair of direction contactors which may be operated mechanically from direction controllers associated with each alternator control or indirectly therefrom by means of an electric servomotor the direction switch of which is so operated. The alternators are each driven by a turbine. The first control stage drives them up to 1 /5 full speed whereupon the motors run up to synchronism as induction machines. They are then synchronized by closing their field circuits, whereupon the alternator field is reduced by exciting a negative booster in its field circuit. The turbine is then accelerated to full speed by further operation of its control means. Holding circuits for various contactor switches are arranged to be maintained on reverse movement of the control means right down to the lowest speed position thereof which corresponds to <1>/30 full speed, and the operation of the electric servo-motor opening the main circuit at each direction which is delayed for sufficient time to ensure that circulating movements due to collapse of field flux have died down. Fig. 3 shows the aft end of four bays of motor isolating switches and motor field isolators 17-37, each above a direction switch 13-16 for one motor, while Fig. 4 shows a side view of one bay comprising four selector switches and field isolators 17-20 with direction switches 9, 13 for one motor and an alternator control panel 296, one such being disposed beneath each bay. Fig. 3 shows also two of the four alternator and alternator field isolator cubicles 45, 46. The motor and motor field isolators 17-20, &c., of each bay are individually operated by handles such as 263 to effect connection with one of the alternators but each is locked until a handle 284 has been set to select the alternator. Movement of this handle locks in position a cubicle opening key 295 which is free in a position of the handle 284 which locks all the switches in the off position. Movement of the handle such as 263 actuates a cam 314 to render effective or ineffective an interlocking lever 317 operative between the alternator control means 297 and the direction switches 9, 13 of the motor. Each alternator control means 297 is associated with an interlock lever 301. Before the motor-alternator connections can be changed the lever 301 must be thrown over. This locks the control wheel 297 in the " off " position to which it must first have been moved and also turns through gearing a shaft such as 302. Each direction control wheel 298 similarly turns a shaft such as 304. The shafts 304 are each geared to a shaft such as 403 which may operate through a clutch such as 400, the direction contactors mechanically; normally however the wheels 298 operate reversing switches 167, Fig. 2, for servo-motors 188 operating the direction contactors. In order to effect an interlock with any one of the direction controllers a disc such as 303 fast on each shaft such as 302 is coupled by rods 421 with discs 408 loose on each of the other shafts such as 302. The disc 303 fast to each alternator control is also linked to an interlock disc such as 417 proper to that alternator. Each of the shafts such as 304 carries four discs such as 305 fast thereon by which means each direction controller may be interlocked with the control means of that alternator with which the motor is for the time being connected by any given isolator 17-20 this interlock being rendered effective by the cam 314 which is moved when the isolator is operated. The alternator and alternator field isolators cannot be closed by the handle such as 310 unless the alternator control is in the off position, i.e. unless the interlock lever 301 of that alternator is thrown over to release inter alia the interlock such as 417. The motor isolators are locked so that none can be moved until the interlock lever 301 has been thrown over ; this is effected by gearing 437 coupling a shaft such as 436 proper to each alternator to each shaft such as 302. The shafts 436 carry interlock discs co-operating with interlock discs on each motor isolator shaft such as 262. Figs. 7, 8 and 12 show the nature of the interlock apparatus. The illustrated portion of Fig. 1 shows the main and field circuit arrangements of one motor 5 and one alternator 41. The bus-bar 21 is connected through the isolating switch 45 to this alternator whilst the bus-bars 22-24 are similarly connected to the remaining alternators respectively. The motor isolators 17-20 and the alternator isolator 45 are coupled to field isolators, the former being respectively associated through the field bus-bars 25-28 with the circuit supplying the field of one of the alternators. The excitation of the motor 5 and of the alternator 1 is obtained from a suitable source (not shown) through respective field contactors 61, 53, the former being coupled to a switch 77 which excites a negative booster 69 in the alternator field circuit when the motor is excited for synchronizing. Reversing contactors 9, 13 are included in the motor circuit Fig. 2 shows the control circuits associated with one alternator and one motor. The drum controller 82, the alternator field contactor 53, the motor field contactor 61 and the booster field contactor 77 are all contained in the control panel 296 proper to the respective alternator the first being operated by the control wheel 297. The switches 17A-20A and 17B-20B are auxiliary switches coupled to the motor and motor field isolators respectively. The switch 167 is operated by the direction control wheel 298 and the drum switch 168 is coupled to the direction switch motor 188 which is driven in appropriate directions by selectively energizing the field windings 183, 184.