Patent GB-150559-A (GB)
Title: Improvements in or relating to alternating current rectifiers
IPC: H02J7/02
Filed: 1919-10-22
Abstract: 150,559. Wade, H., (Mills, H. S.). Oct. 22, 1919. Commutator switching- arrangements.-In a rectifying system for charging storage batteries, comprising a synchronously-driven commutator switching-arrangement F and a circuit-breaker E in the direct-current charging line, the circuit-breaker is controlled by an overload and reverse-current relay C in the charging line, and by an alternating-current relay B. The circuit-breaker is closed by an electro-magnet 44 in a shunt circuit 108 across the direct-current leads 104, 105. This shunt circuit includes contacts 35, 36 of the relay C, and contacts 26, 28 of the relay B, both sets of contacts being normally closed when the system is in operation. On closing the main alternating-current switch A, Fig. 7, a plunger 14 is moved against the action of a spring 17, and is held in the retracted position by the engagement of a collar 15 on the plunger with a lug 16 carried by the armature 18 of an electro-magnet 19. After a predetermined time or when a predetermined charge has entered the battery, a meter D closes the circuit of the electro-magnet 19, and the plunger 14 is released to open the switch A. The collar 15 and lug 16 are in the shunt circuit 108 so that the closing of the main switch also closes this circuit and energizes the electro-magnet 44 of the circuit-breaker E. The circuit-breaker, Fig. 2, comprises a pivoted arm 42 carrying a main contact 45 cooperating with a contact-brush 48, and an auxiliary carbon contact 46 co-operating with a graphite rod 51 and with a pivoted carbon contact 53. The rod 51 is carried by a pivoted arm 50, and the contact 53 is journaled between arms 52 and controlled by a leaf spring fixed to the base and by a helical tension spring 56 connected to the arm 50. A stud 63 on the lower part of the arm 42 engages an L-shaped slot in a link 61 connected by an arm 60 and escapement-gearing to a fan 68 which retards the first part of the closing movement when the electro-magnet 44 is energized. On closing the switch A, the magnet 44 is energized with the full current from the battery and the circuit-breaker starts to close; at the same time the motor driving the rectifier F is supplied from the winding 101 of a transformer H and starts to run as an induction motor. The final part of the closing movement of the circuit-breaker takes place rapidly when the stud 63 passes the bend of the slot in the link 61, and, just before this happens, contacts 75 in a shunt circuit 106 engage the arm 42 to energize the direct-current field of the motor, which thereupon runs as a synchronous motor. In the full-on position of the circuit-breaker a contact 69 passes off a pivoted contact-member 70, and a resistance 109 is placed in series with the electro-magnet 44. The alternating-current relay, Fig. 6, comprises a double-pole electro-magnet 20, to one pole of which is pivoted an armature 21. The opposite pole is provided with an extension placed in proximity to a leaf spring 23 which can be weighted at 24 in order to adjust its pericdic time of vibration. The natural frequency of vibration of the spring is less than the frequency of the current, so that the spring is only set in vibration when the frequency of the current falls below its normal value. In that event the vibrating spring engages the arm 31 of a four-armed contact-lever and separates the contacts 26, 28, thereby opening the shunt circuit 108 and deenergizing the electro-magnet 44; the circuitbreaker then opens by gravity aided by the spring 56. If the alternating current fails altogether, the electro-magnet 20 is de-energized and the armature drops on to an arm 30 of the contactlever and opens the circuit. The direct-current relay C comprises a shunt winding 32 and a lowresistance series winding 33, Fig. 6, the contact 35 being carried by an armature 34 pivoted to the pole-piece of the electro-magnet 32. The two windings are normally of the same polarity, but an excessive current in the winding 33 induces an opposite pole in the end of the armature and causes the separation of the contacts 35, 36. A reverse current through the winding 33 has the same effect. The contact 36 is adjustable vertically to vary the limit of overload at which the relay becomes operative. The shunt winding 32 is supplied with current from a contact 74 which engages the arm 50 when the circuit-breaker moves into the closed position. Both relays B, C return automatically to running position when normal conditions are re-established. An inductance G is placed between the rectifier and the direct-current circuit.