Patent GB-282856-A (GB)
Title: Improvements in or relating to automatic starting and stopping arrangement for turbines
IPC: F03B15/16
Filed: 1926-09-23
Abstract: 282,856. Trefz, F. Sept. 23, 1926. Supplying consuming devices. -Relates to the automatic starting and stopping of turbine generator sets in which a current controlled device mechanically operates the fluid supply to the turbine and connects the load circuit. The current controlled device permits admission of the fluid supply to the turbine in upper and lower limit positions and closes the supply in an intermediate position into which it moves by gravity or otherwise from the upper position. From the intermediate position it is moved automatically by the energy from a primary battery to the lower position and from this position it is returned to the upper limit position again at a definite speed of the turbine. In a modification, the return movement is effected electromagnetically as shown diagrammatically, Fig. 1, a governor or servomotor 9 controlling the fluid supply to the turbine is connected to a contact bell-crank lever 1, 1<1> by a link 2 and guide-rod 3. In the " up " position of the bell-crank arm 1<1>, the turbine runs the generator 5 and the electric circuit is completed through the arm 1<1> and contact 7, the energized electromagnet 6 retaining the arm in its " up " position. If the circuit 8 is broken, the arm 1<1> falls by gravity and is held in its intermediate position by a trip catch 16 the fluid supply to the turbine then being stopped. In this position, and when the consumer circuit 8 is again connected a circuit through the relay galvanometer 12 and contact 10 is made. The galvanometer contact needle 13 is deflected in either direction to a contact stop 14 and the auxiliary circuit is closed through a primary battery 11 and solenoid 15. The current through the galvanometer coils may be sufficient to operate the solenoid 15, but in anv case this current is strengthened by that through the contacts 13, 14 and is then sufficient to trip the arm 1<1> so that it falls into its lower position. The liquid supply to the turbine is then opened and the bell-crank lever is restored to its " up " position, the consumer circuit being again connected at the contact 7. Constructionally, Fig. 4, the bell crank lever 1, 1<1> positively connected with the switch arm carries a cross-plate 17 having a hook 26 engageable with a resilient plate 25 rotatable on an axis 24 and connected with a lever 23. The free end of the lever 23 seats behind a projection 22 on a rotatable armature plate 21 which is engaged by an arm 18 carried by the cross-plate 17. In order to prevent the arm 1<1> from springing away from the hook and plate attachment 25, 26, a heavy latch 27 momentarily retains the parts in position until secure engagement has occurred. The latch 27 then sinks back under its own weight and leaves the arm 1<1> free to be released by the electromagnet 6. On release the arm 1<1> falls into its intermediate position where it is held by a spring-pressed plate 34 forming with the arm 38 the trip catch 16 (Fig. 1). The free end of the arm 38 engages behind a catch 40 on the armature 41 of the solenoid 15. Energization of the solenoid 15 permits the arm 1<1> to fall into its lower position. From the lower position it is returned to the " up " position by governor mechanism comprising a pulley 43 driving a centrifugal governor contained in a housing 44. The governor controls an axially movable shaft 51 carrying a spur wheel 53 which, on the turbine reaching a definite speed, meshes with a gear wheel 54 on a crank shaft 55. The crank 59 is provided with a roller 57 engaging the arm 1<1> which is thereupon pushed into its " up " position. In order to free the meshing gears 53, 54 a releasing arm 68, Fig. 3, follows the movement of the arm 1<1> until the latter is near its "up" position, the arm 68 is tripped and operates a lever 70, bell-crank 71 and rod 72 to tilt the bearing bracket 63 on its pivot 64. This movement withdraws the pinion 53 and at the same time an arm of the bell-crank lever 71 is held behind a resilient stop 78. When the arm 1<1> falls from its intermediate position upon energization of the electromagnet 15 through the relay galvanometer 12, a lever 79 connected with the arm 1<1> pushes the stop 78 back, frees the bell-crank 71, and allows the parts 63, 43, 44, 53 to return under the action of a spring 77. In a modification, Fig. 6, these axially movable parts are replaced by an electromagnetic arrangement for returning the arm 1<1>. From the contact 10 to the lower position 85 of the arm, a long arcuate contact 84 permits energization of the field windings 82 for turning the armature 81. connected with the arm 1<1> into its fully attracted position.