Patent GB-190525512-A (GB)
Title: Improvements in and relating to Controlling Apparatus for Electric Circuits.
Filed: 1905-12-07
Granted: 1906-12-07
Abstract: 25,512. British Thomson-Houston Co., [General Electric Co.]. Dec. 7. Electric railways and tramways.-In a direct-current distributing-system, the third-rail sections are connected by leads to a single feeder, the leads being connected through a main switch and a circuit - breaker controlled by motordriven mechanism which opens the switch, closes the circuit-breaker, and finally closes the switch. The switch A and circuit-breaker B are of known constructions, shown in Figs. 1, 2, and 3. The switch A has a contact-bridge 12 pivoted to the arm 16, and is operated by a rod 22 through a toggle formed by the projection 24 and lever 23. Auxiliary contacts 17, 18 are provided to remove sparking from the contact-stud 10. The circuit-breaker B is of similar construction, and is provided with a contact arm 28 which may be operated through toggle-levers by the rod 70. The arm is supported inside a frame 41 secured to the support 13, while the arm 39, supporting the auxiliary contacts, are outside the frame 41. The projection 46 on the lever 47 engages a projection 48 on the frame 29. To close the circuitbreaker, the arm 47 is moved downwards and inwards, thus rocking the frame 29 to make the bridge 28 close the circuit between the contacts 26, 27. The movement is stopped just before the main toggle formed by projections 46, 48 reaches a dead-centre. The parts are then locked by a latch 49 engaging a projection 51 on the arm 47. The frame 41 has a pair of levers 55, 56 on each side connecting it to the auxiliary contact arm, and these are moved by shoulders 56<a>, 57 on the sleeve 58 engaging with shoulders 59, 60 on the links 56. Stops are provided to arrest the toggle in a slightly overset position. The U - shaped frame 43 is made of iron to form a magnetic turn about the circuit from contact 10, arm 12, contact 11, strip 15, contact 27, arm 28, to contact 26. An armature 63 is pivoted to the frame 43, and is arranged to trip the latch 49 when an overload occurs. A calibrating-screw 65 is provided so that the tripping may take place with any desired overload. An auxiliary trip is furnished by the solenoid 67 in a case 68 and an armature 69 to engage the latch. The latch may also be tripped by means of a push-button 53. The lower ends of the rods 22, 70 are connected by curved members 74, 75 to cranks 76, 77 on the shaft 78 driven by any motor 80 through worm gearing. The motor 80 requires reversal to give the cranks 76, 77 a to-and-fro motion, and a flexible spring 88, Fig..7, is connected between cylindrical members 86, 87 keyed to the two sections 84,85 of the shaft.. This spring absorbs the mechanical shock on reversal and enables the motor to speed up and develop a back electromotive force to prevent serious sparking at the brushes. The reversing-switch R has a contact 90 and a pivoted arm 89 which may bridge a pair of contacts 91 or the reverse pair 92. These contacts are carried by arms 93 on the frame 94, and stops 95 limit the movement of the switch arm 89. An arm 96 of the switch S, Fig. 5, carries a contact 97 which bridges the contacts 98. A cam 100 is keyed to the shaft 78, and an arm 101 loose on the shaft is connected to the switch arm 89 by a link 102. Another arm 103 is keyed to the shaft, and the two arms 101, 103 carry pins 104; 105 to engage the ends 106, 107 of a spring 108 which gives a snap movement to the switch R. The arm 101 has a projection 109 which may engage with shoulders on the latch 110 pivoted to an arm 93. When the shalt 78 rotates in the direction of the arrow 111, the cam-face 112 causes the switch arm 96 to bridge the contacts 98 and the latch 110 engages the projection 109 locking the arm 101. As the rotation continues, the pin 104 carries round the end 107 of the spring 108 to increase the tension on the spring, until the cam-face 112 raises the latch 110 away from the projection 109. The spring 108 then pulls the arm 101, and throws the switch arm 89 on to the contacts 92. The motor 80 then reverses, rewinds the spring, opens the switch S, and raises the latch 110, allowing the switch arm 89 to move on to the contacts 91 under the action of the spring. The crank 76, which operates the main switch A, is loose on the shaft 78, and is provided with a projection 114 which engages a projection 115 on a sleeve 116 keyed to the shaft. A spring 117 engages projections on the crank and sleeve, and tends to keep the two in engagement, while the shaft rotates in the direction of the arrow shown in Fig. 8. During the return movement, a projection 121 on the crank engages a stop 122. The shaft continues to rotate, putting greater tension on the spring 117 until the . members 122, 123 are rocked by the cam 124 on the sleeve 116, thus allowing.the crank to complete its rotation under the action of the spring. This gives the main switch a snap action in closing. Two switches 126, 127 are actuated by the moving parts 12, 28 of the switch and circuit-breaker respectively. A preferred form is shown in Fig. 14 of a double-throw switch 127, the other switch 126 being a single-throw switch of similar construction. A disk contact 131 carried by a plunger 132 may bridge the contacts 129 when the button 133 is depressed. A rectangular contact 135 on the plunger 132 travels in a slot 135<a> and is kept by the spring 134 in a position bridging the contacts 130. The case may be cut away at 138, 139, so that, when the disk 131 is in its midposition, the plunger may be rotated and held by pins 140 engaging the contact-block 135. The connexions are shown in Fig. 19. The bus-bar 143, which may be the bus-bar in the substation supplied with direct current from rotary converters, supplies power to the third-rail section 145 through a feeder 144, circuit - breaker B, and switch A. These switches and the motor 80 are located near the section they control, and a single wire 158 runs to a control switch 160 at the substation cr other desired control point. Indicating-lamps (red 165 and green 166) are arranged in circuit as shown. When the switch and circuit-breaker are closed, the mechanism is in the position shown in Fig. 1. Current then passes through the red lamp 165 from the feeder 144 by the leads 147, 159, 158 to the ground 164. This current flows through the coil 67 but is insufficient to trip the circuitbreaker B. To disconnect the third rail from the feeder, the arm of the switch 160 is thrown on to the contact 162, thus short-circuiting the lamp 165. This increases the current through the coil 67, which attracts its armature 69 and opens the circuit - breaker B. As it opens, the arm 28 depresses the push 133, breaking the circuit across the contacts 130 and completing another across the contacts 129. The circuit-breaker B may also be tripped by an excess current in the lead 146 operating the armature 63. The push 133 closes a circuit through lead 163, green lamp 166, leads 158, 156, 154, and track 153, to ground. The green lamp indicates that the lead 146 is open. To connect the feeder again to the third-rail section, the switch arm 160 is thrown on to the contact 161, short-circuiting the lamp 156 and closing the electro - magnetic switch 155; This completes a circuit from the feeder 144 through the leads 147, 150, contacts 91 of the reversing-switch R, lead 152, and the motor 80 to ground at the rail 153. The motor operates the mechanism to open the switch A and close the circuit-breaker B, which is locked by the catch 49. The switch arm 96 bridges the contacts 98, completing a circuit for the motor independent of the switch 160. The switch R reverses the motor, which then operates to close the switch A. The switch arms 89, 96 are thrown to their normal positions, and the circuit through the red indicating-lamp 165 is completed across the contacts 126, 130. When the circuit - breaker is open, the circuits may be disconnected for repairs &c. by putting the push 133 in its mid position.