Patent GB-190507591-A (GB)
Title: Improvements in connection with Alternating Current Dynamo Electric Machines for Synchronizing, and Connecting, them with Distributing Conductors.
Inventor: JOHNSON JAMES YATE
Filed: 1905-04-10
Granted: 1905-11-23
Abstract: 7591. Johnson, J. Y., [Voigt & Haeffner Akt.-Ges.]. April 10. Switches. - One arrangement of apparatus for synchronizing alternating-current machines and for automatically, connecting them with the mains when the tension and phase of the machine coincide therewith is shown in Fig. 1. The alternator 2 communicates with the mains a, b, c through switches a<3>, b<3>, c<3> controlled by a solenoid 7, and an independent source 26 of either direct or alternating current, which may also be used for exciting the several alternators &c., is connected with the synchronizing-circuit, which includes a differential tension relay T, a phase indicator and relay P- comprising an incandescent lamp 51 and an electromagnet 52 which is adapted to close the circuit 28, 29 of a solenoid 58 when the phases and frequencies of the alternators 1, 2 are alike-a normally-closed subsidiary relay S, and a switch 63 serving to energize the, solenoid 7. One solenoid 41 of the relay T communicates with the alternator leads a<4>, b<4>, and the other solenoid 40 with the mains a, b. When the tension of the alternator 2 drops below or rises above that of the mains, the switch arm 34 strikes one or other of the contacts 35, 37, closing the circuit of the relay S, which thereupon breaks the synchronizing-circuit at 49. The relay T may be provided with only one coil 41, if the spring 47 is so adjusted that it normally forces the lever 34 up against the contact 35 and only allows the lever to take up the middle position when the tension of the alternator is equal to that of the mains. In this modification, the circuit 43 is omitted with the exception of the portion 44 running from the lead b<2> to the phase relay P. The movement of the core 59 of the solenoid 58 is controlled by a time-limit device which permits the core to rise only very slowly but allows it to drop immediately upon the cessation of current in the solenoid. As shown in Fig. 2, the top of the core is formed as a rack which drives a fly 83 by means of a ratchet-wheel and pawl 84, 88 and a train of wheels. The contact carried by the core 59 closes the circuit of the solenoid 7, the core 6 of which, Fig. 1, carries a switch 8 at its upper end, and is locked in its lifted position by means of a bellcrank lever, the arm 10 of which enters into a notch 9. The arm 11 of this lever acts upon a spring-controlled bell-crank lever 15, 16, the hooked end 16 of which engages the head 18 of the core 23 of a solenoid 24, and keeps the switch 25 locked when the switches a<3>, b<3>, c<3> are open. In operation, the switch 69 is first closed, and, on the closing of the switches a, b<3> c<3>, and 8, the rod 3 is locked-by means of the bell-crank lever 10, 11, the dropping arm 11 of this lever releases the arm 15, and the solenoid core 23 then falls, opening the circuit of the solenoid 7. To disconnect the alternator 2 from the mains, the circuit of the solenoid 24 is closed by means of a switch 76, and the head 18 of the rising core 23 strikes against the arm 11 of the lever 10, 11, and withdraws the arm 10 from the notch 9, causing the rod 3 to drop and open the switches a<3>, b<3>, c<3>. In order to connect the alternator to the mains when the latter are devoid of current, the switches 69, 76 are opened, and the switch 76<a> closed to energize the solenoid 7. In the system shown in Fig. 5, the operation of which is similar to that of Fig. 1, the phase indicator consists of two transformers B, C having a common secondary circuit, in which is arranged a lamp L and from which the phase relay P and the tension relay T derive their current. The contactarm 113 of the relay T is connected to one of the line-wires d of an independent source of current (not shown), and the solenoid 119 of the subsidiary relay S communicates on the one hand with the contact-pieces 114, 115 and on the other hand with the return wire e. Incandescent lamps L', L<2> indicate when the tension of the alternator drops below or rises above that of the mains, and a lamp L<3> lights up when the tensions coincide. A differential solenoid with thin- and thick-wire coils 144, 145 controlling a switch 147 is arranged in the synchronizing-circuit, and serves to prevent the automatic apparatus from again working should it become necessary to open-circuit the switches a<3>, b<3>, c<3> for any reason. The upper solenoid 144 is first energized, and closes the switch 147 until the switch 63 of the time-limit device is closed, when its current is shunted through the path 142, 151, while the solenoid 145 receives the whole current of the solenoid 7 and maintains the switch 147 closed. When the circuit of the solenoids 7, 145 is broken at the switch 25, the switch 147 automatically opens. To give the switches a', b<3>, c<3> a sufficient time to close even which the circuit 142, 151 of the time-limit device is momentarily broken, a safety device is inserted in the circuit of the solenoid 7 consisting of a small solenoid 157 controlling a switch 158. In some cases, the regulator for exciting the alternator may be provided with adjustable contact-pieces at a point corresponding to the correct tension, and the contactpieces are connected with the tension relay T for controlling the latter.