GB325269A - Improvements in or relating to power systems - Google Patents

Abstract

325,269. Johnson, E. M., Pierson, H. C., and Associated Electrical Industries, Ltd. Nov. 15, 1928. Electric governors; transmitting-mechanism.- In motor power plant of the kind in which a primary engine, and a secondary engine using the exhaust of the primary engine both operate the same drive, the secondary engine is coupled to the main drive by variable transmission means the ratio of which is varied automatically in order to keep constant the speed of the secondary engine. At a limiting point the governor may admit fresh steam to the secondary engine. Figs. 1, 2, and 3 show the application to a ships propulsion plant comprising a reciprocating engine 1 driving a propeller 3 direct and an exhaust steam turbine 4 driving the same propeller through an electrical transmission comprising a generator 10 and a motor 11. The turbine 4 also drives a generator 12 for the auxiliary services of the ship. A stage 8 of the turbine may be supplied with steam by a pipe 9 controlled by a valve 17, and a valve 7 is arranged to bye-pass the exhaust of the engine 1 to the condenser 5. Rheostats 14, 15 and a reversing switch 13 are arranged in the field circuit of the generator 10. One or two governors 16, 18 are provided to regulate (a) the resistance 15 inserted in the field circuit of the generator, (b) the opening of the valve 17 controlling the auxiliary fluid supply. and (c) the closing of the valve 7 which byepasses exhaust steam to the condenser. Fig. 2 shows a mechanical device for transmitting the governor movement. The governor actuates a relay motor 23 having a rod 24 with pins 25, 26, engaging arms 20, 27. On the speed falling the arm 20 begins to increase the resistance 15 and so reduces the load on the generator 10. When the limit of this reduction is reached, a stop 32 on the arm 27 engages an arm 33 and through a connection 34, 28, 22, begins to open the auxiliary fluid supply valve 17. The intermediate gear may be modified. Fig. 3 shows an electric governing apparatus which may be used instead of a centrifugal governor for actuating the mechanical transmission apparatus shown in Fig. 2. The auxiliary generator 12, the voltage of which is to be maintained constant, is connected to a voltage relay 44 comprising coil 45, plunger 46, restraining spring 47 and two pairs of contacts 50, 51. The circuits of these contacts control a reversing contact maker 48 by which the direction of rotation of a servo-motor 49 is determined. The servo-motor actuates transmission gear such as that shown in Fig. 2. The plunger 46 may actuate an oil servo-motor instead of the electric servo-motor 49. The second governor 18 shown in Fig. 1 mav act as an emergency governor. The main engine 1 may be uncoupled from the propeller shaft. Variable hydraulic transmission may be used between the engine shafts instead of electric transmission.