US2467116A - Rectifier circuit arrangement - Google Patents

Description

April 12, 1949.

D. M. DUINKER RECTIFIER CIRCUIT ARRANGEMENT Filed Feb. 8, 1947 div . M- DUINKER Patented Apr. 12, 1949 RECTiFIE-R Daniel Marie Duinker, Eindhoven,

CIRCUIT ARRANGEMENT.

Netherlands,

assignor to Hartford National Bank and Trust Company, Hartford, Conn, as trustee Application February 8, 1947, Serial No. 727,426

In the Netherlands July 8,

Section 1, Public Law 690, August 8, 1946 Batent expires July 8, 19M

6 Claims. (01.. 315- 261) This invention relatesto a circuit arrangement for a rectifier, which comprises one or more gasor vapour-filleddischarge tubes having an incandescent cathode and anauxiliary electrode, and which is furthermore equipped. with a device, for instance abi-metallic relay which permits the rectifier to be put into, circuit in a retarded manner known per se.

In such circuit arrangements comprising noncontrolled tubes it has hitherto been customary to make the bi-metallic relay operate a magnetic switch in the main current circuit (either at the primary side or at the secondary side), by the fact, that upon closing the bi-metallic contact the coil of the switch is energised. Such a device has the drawback that the construction of the switch is comparatively expensive especially below a definite value.

The present invention has for its object to provide a circuit arrangement of the kind referred to above, in which the magnetic switch is omitted and which is preferably designed in such a manner as to permit the use of rectifying tubes of the kind that are controllable by means of an auxiliary electrode, which need not be ignited anew by an auxiliary ignition device before every passage of the current.

According to the invention the ignition voltage on the auxiliary electrode in starting up the rec tifier upon closing the contact of the bi-metallic relay is applied either indirectly or directly through this contact to the auxiliary electrode.

Tubes. are preferably used which in the deionised state have a positive ignition characteristic and a de-ionisation time which amounts at least to a quarter cycle of the operating A. C. Well-known tubes of this kindare, for instance, rectifying tubes for a feed voltage of from 100 to several hundreds of volts having a gas-filling, an incandescent cathode and a so-called cathodescreen, which usually serves to reduce the risk of backfire in the tube. This screen acts as a grid in a relay tube in so far as the ignition voltage is high if the screen has the same potential as the cathode or is slightly negative with respect to the cathode, and if sufficient time has elapsed since the previous discharge in the tube. In this de-ionised state the tube has a so-called positive ignition characteristic i. e. that upon switching on, a positive current impulse has to be supplied to the screen to ignite the tube. If, however, care be taken, such as is feasible by a suitable choice ofthe dimensions, andby a sufficient gas pressure, that the de-ionisation time at least amounts to a quarter cycle of .the operating A. C.,

has become .sufficie parallel with the so that the tube isnotyet deeionised afte'ra quarter cycle, then in cases where the currentless in? terval between two succeeding anode currents of one and the. same tube amounts to cycle or more, the re-ignitionvoltage for the next passage of current will be low so, that the auxfliary ignition need not take place for, re-ignition in this and the next cycle. Inpractice, this state often occurs in charging accumulator batteries by means of a two-phase rectifying tube. 1f single-phase tubes are used it will be necessary to use a de-ionisationtime of at least half a cycle.

In order that the invention maybe clearly understood and readily carried into effect, it will now be described more fully with reference to the accompanyin drawing, which represents, by way of example, two embodiments thereof. Each figure shows a circuit arrangement for two-phase rectification. For simplicity corresponding circuit parts bear the same reference numerals.

In Figure 1 the reference numeral i denotes the terminals of the A. C. mains to which is connected, through a switchZ, the primary, 3 of a transformer 4. To the secondary 5 is connected in a manner known per se a double-phase rectifying tube 6 whichtogether with the anodes l and 8 has a common grid 8. and the incandescent cathode Ill. A load resistance I2 is connected in D. C. network between the connecting terminals H.

The controlvoltage for the tube 6 is supplied through the intermediary of a valvelS, for in.- stance a high-vacuum tubeanda bi-metallic relay l4. To this end the anodes l5 and It of tube l3 are respectively connected to one or both halves l1 and E8 or the secondary 5 of thetransforrner 4 and the incandescent cathode l9, through the heating member 20 and the resistance 2i to the incandescent cathode! and consequently also to the positive terminal of the direct current net,- work H. The movable part 22 of the bi-metal relay is likewise connected to the incandescent cathodev [f tube l3 and the fixed contact 23 through a limiting resistance 2i to the grid 9 of tube 6. The potential-of the grid 9 relatively to the cathode I0 is determined by the resistance 25.

The operation of the device described, which has for its object to switch on the rectifying tube 6 in a retarded manner in conjunction with possible damaging oi the incandescent cathode, is as follows:

After closing cathodes l0 and-L9;

the switch 2 the incandescent arebea d- W enthe latter .tlybot a current. passes. in

accordance with the polarity, from one of the secondary windings l1 and I8 through one of the anodes I5 and IS, the heating member 20, the rethe resistance l2 be the load itself if it has already been put into circuit) to the mid-point tapping of the secondary of transformer 4. After a certain delay the bi-metal 22 engages the contact 23 and on the auxiliary electrode 9 of the tube 6 is set up such a positive voltage relatively to the incandescent cathode as to permit ignition of the tube 6 in one of the anode circuits. At this moment a current is still flowing through the heating member 20 and the resistance 2|. The desired current distribution over the two branches can be obtained by a judicious choice of the resistance 2| and 24.

The tube 6 having been ignited, the D. C. network is fed and the voltage of the anodes 1 and 8 falls off to the arc voltage of the tube. Due to this current through the tube l3 falls off to such a degree that the bi-metal cools and the contact is opened at 23. The auxiliary current through this contact is then interrupted, it is true, but the tube 6 keeps operating, since its de-ionisation time exceeds a quarter cycle of the alternating feed current, as a result of which the re-ignition is low in the second and switching on by means of an auxiliary ignition, as obtained upon switching on through the tube I3, is superfluous.

Thus it is feasible to switch on in a retarded manner and to feed, upon switching on, the D. C. network so long as the switch 2 is closed, without the tube need be ignited by a separate auxiliary voltage in each half cycle. After cooling down the bi-metal 22 is ready again to bring about the desired delay upon switching on again by means of the switch 2.

The circuit arrangement shown in Fig. 2 is a variant of Fig. 1, in which the additional load resistance l2 shown in Fig. 1 is omitted, or the network load need not be put into circuit, before starting up the rectifier.

Upon closing the switch 2 the heating member 20 is traversed by current from an auxiliary winding 26 of transformer 4, which current passes through the switch 2'! and the contact at 28 of a relay 29. Upon closure of the contact 23 an auxiliary current may pass from the auxiliary winding 38 of transformer 4 through the tube It, the contact at 28, contact 23 and coil 3! of the relay, resistance 24, auxiliary electrode 9 and incandiescent cathode IE] to the :midpoint tapping of the auxiliary winding 30. Owing to this the tube 6 is capable of igniting 1. A power supply system comprising a gaseous rectifier tube having a control electrode, a timedelay relay having a normally open switch and an electrically energized element for actuating said switch, a source of alternating voltage, rectifier means to derive an ignition voltage from energizing current lowing an interval determined by the characteristic of said relay said switch is actuated by the energized element and said ignition voltage is applied to said electrode to fire said tube, and

from said source, means to impress for rectification an alternating voltage from said source onto said tube and simultaneously to supply said reopen.

3. A power supply system comprising a gaseous rectifier tube having a control electrode, a thermostatic relay having a normally open bimetallic switch current flow through said heating element thereby causing said switch 4. A power supply system comprising a voltage transformer having a primary and a centertween said control electrode and the junction of said element and said first resistance through said switch, a. third resistance connected between the centertap of said secondary and the cathode of said tube, and means to apply an alternating voltage to said primary.

secondary, a gaseous rectifier tube having a cathode, a pair of anodes and a controlelectrode, said anodes being connected to opposite ends of said secondary, said tube having a positive ignition characteristic in the deionized state and a deionization cycle of an applied alternating voltage, a rectifier device having a cathode and a pair of anodes connected to opposite ends of said secondary, a thermostatic relay having a, normally open bimetallic switch and an electrical heating element for actuating said switch, a first resistance, the cathode of said device being connected through said heating element and said first resistance to the cathode of said tube, a second resistance connected between said control electrode and the junction of said element and said first resistance through said switch, a third resistance connected between'the centertap of said secondary and the cathode of said tube, and means to apply an alternating voltage to said primary.

6. A power supply system for a load, said system comprising a voltage transformer having a primary, first and second centertapped secondaries and an auxiliary winding, a gaseous rectifier tube having a cathode, a pair of anodes and a control electrode, said anodes being connected to having a normally closed opposite ends of said first secondary, a rectifier device having a cathode and a pair of anodes connected to opposite ends of said second secondary, a thermostatic relay having a normally open bimetallic switch and a heating element for actuating said switch, an electromagnetic relay armature switch and a coil for actuating said switch, said heating element being connected through said armature switch across said auxiliary winding, a first resistance, the cathode of said device being connected through said armature switch, said bimetallic switch and said first resistance to the cathode of said tube, the junction of said resistance and said bimetallic switch being connected through said coil to said control electrode, the centertap of said second secondary being connected to the cathode of said tube, and means to connect the load between the centertap of said first secondary and the cathode of said tube.

DANIEL MARIE DU'INKER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS

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