Patent GB-470129-A (GB)
Title: Improvements in or relating to apparatus for producing large impulses of electrical energy of short duration
IPC: B23K11/26
Filed: 1936-05-21
Abstract: 470,129. Exciting alternators; control systems for high-frequency apparatus. VERTRIEBS-GES. DES LEIPZIGER LEICHTMETALL-WERK. May 21, 1936, Nos. 14442 and 14443. Convention dates, May 22, 1935 and April 8, 1936. Addition to 432,041. [Classes 35 and 38 (iv)] [Also in Group XXXVII] Switching control.-In apparatus for producing large impulses of electric energy of short duration by means of a medium or high frequency alternator, the exciting current of which is controlled by a switch device having an adjustable contact time, as described in the parent Specification, a further switch device is provided in the output circuit of the alternator. The switches, if mechanical, are preferably of the rotary drum type, but gas or vapour discharge devices may also be employed. The two switching devices are interconnected and preferably so controlled that the switch in the field circuit is both closed and opened before that in the output circuit. To assist in the interruption of the load current the alternator or its exciter, may be excited by alternating current, or the field current of the exciter may be periodically reversed, reversal of current in the output circuit being prevented by reverse current breakers or grid-controlled discharge devices. In the arrangement shown in Fig. 5, the output circuit of the alternator 20 is controlled by a rotary switch 29 having two sets of contact segments 29<1>, 29<11>, making contact with a roller 30, the segment 29<11> sliding between the segments 29<1> as shown in Fig. 5a, so as to regulate the time of contact. On the same shaft as the switch 29 are two drum switches 23 arranged to reverse at each rotation the field current of a machine 10 which excites the alternator 20. Reversal of the field current of the machine 20 is prevented by a discharge device 24 which is also controlled by a grid. This grid is excited to permit the passage of current by the discharge of a con denser 26 charged by a battery 26<1> and discharged by a hand or automatically operatedswitch 28 and a rotary switch 25 on the same shaft as the switches 23, 29. The period of discharge of the condenser 26 is less than that of rotation of the switch 29, so that a further current impulse is not produced when the switches 23, 29 again make the appropriate contacts unless the switch 28 is also operated. Fig. 6 shows an arrangement in which the alternator 20 is excited from mains through a rectifier 33. Discharge through this rectifier is normally blocked by grids 34, but this blockage is periodically removed by reversing the polarity of these grids through switches 35 on the same shaft as the switch 29 controlling the output circuit of the alternator 20. Discharge can then be produced by an ignition grid excited by a condenser 26 charged and discharged through rotary switches 25, 28<1>. The switch 25 is on the same shaft as the switches 35, 29 and the switches 28<1> are driven from this shaft by adjustable gearing 43. Fig. 7 shows an arrangement in which the alternator 20 is excited from mains through a cam operated switch 42 and its output circuit is controlled by discharge devices 37 arranged to utilize both half-waves. These discharge devices are provided with ignition grids excited from a condenser 26 as described in connection with Fig. 6, and with blocking grids which are released by rotary switches 39 on the same shaft as the cam actuating the switch 42 in conjunction with a condenser operated relay 45 controlled by switches 44 on a shaft connected by adjustable gear with the shaft of the switch 39 or operated by hand.