US2183918A - Rectifier tube and circuit arrangement therefor - Google Patents

Description

Dec. 19, 1939. I

J. G. w. MULDER 2,183,918

RECTIFIER TUBE AND CIRCUIT ARRANGEMENT THEREFOR Filed Aug.' 31, 1955 2 Sheets-Sheet 1 Jaw/140L1 5 Dec. 19, 1939. J, 5, w, MULDER 2,183,918

RECTIFIER TUBE AND CIRCUIT ARRANGEMENT THEREFOR Filed Aug. 31, 1935 2 SheetsSheet 2 Patented Dec. 19,

UNITED STATES PATENT OFFICE RECTIFIER TUBE AND CIRCUIT ARRANGE- Netherlands,

Application August '1 Claims.

My present invention relates to a novel type of rectifier tube and to circuit arrangements therefor.

In various applications it is of great advantage to be able to use a single rectifying tube with a single transformer to provide alternating current of different voltages, without being required to insert resistances or make use of regulating devices to obtain these different voltages from the tube.

My invention is particularly useful for obtaining rectified currents of considerable values, from one ampere up to several hundred amperes, and for voltages of from several hundred volts to several thousand volts, and particularly for rectifying polyphase alternating currents, and I shall describe it in connection with the rectification of such polyphase currents.

The rectifier tubes according to my invention are of the gas-filled, thermionic cathode type, whereby the term gas-filled includes fillings of one or more gases or vapors, or a mixture of gases and vapors.

Preferably the tubes of a vapor in their filling.

In accordance with my invention, as applied to polyphase rectification, I provide in the tube a plurality of sets of. anodes, all of which cooperate-with a common cathode. The character of the tube is preferably such that one set of anodes supplies with the cathode a rectified current of comparatively low voltage (of the order of a few hundred volts), whereas the other set of anodes supplies with the cathode a rectified current of high voltage (of the order of several thousand volts) proper switching arrangements being provided to selectively operate the cathode with either set of anodes, whereby the tube operates my invention include in either case with a high emciency.

More particularly, I provide a thermionic cathode in a chamber which, in the case of vapor, preferably also serves as a condensation chamber, and in which the pressure is then comparatively high. Within this chamber and in comparatively close proximity to the cathode I place one set of anodes, which, with the cathode, supply the low-voltage, rectified currenti The small electrode distance and high pressure thereby insures a high efilciency, and as the voltage is comparatively low there is no dangerof. back discharge.

The other set of anodes, which supply with the cathode the high-voltage rectified current, I place preferably in separate chambers, and as a rule in arm extensions of the cathode chamber; the

assignor to N. V. lampeniabrieken, Eindhoven,

31, 1935, Serial No. 38,822 Germany September 5, 1934 Philips Gloei- Netherlands vapor pressure around these anodes being comparatively low. This, together with the long discharge path, protects against back discharge, whereas the comparatively greater internal voltage drop does not markedly reduce the efliciency 5 of the tube because of the higher total value of the output voltage.

If the voltage between the low-voltage anodes and the cathode is sufficiently high as to endanger back discharge, I preferably provide screens around this set of anodes, so as to increase the back discharge. Similarly, if the high voltage is excessively high, screens can also be provided around the high-voltage anodes.

Such tubes, made in accordance with the invention, are operated in specific circuit arrangements, which, as well as details of the tubes of the invention, will be more fully described in connection with the drawings.

I am well aware that it has been proposed to 20 provide in a single tube a plurality of anodes or set of anodes, which are selectively operated. Such prior arrangements have, however, either used anodes which were of the same character and symmetrically arranged with respect to the 5 cathode, or again, comprised two rectifier tubes built into one and operating simultaneously without regard to efficiency of, the tubes, Such rectiflers furthermore, only served for very low and medium voltages.

My invention, as stated, makes it possible to rectify in such manner medium and high voltages at large currents, whereby the voltages obtained may differ greatly or only to a small extent from each other; whereas the efliciency remains invariably high. 4

In order that the invention may be more clearly understood and readily carried into effect, I shall describe same more fully with reference to the accompanying drawings in which: 40

Figure l is a schematic wiring diagram of a circuit arrangement according to the invention;

Fig. 2 is a partly sectionized side view of a rectifier tube made in accordance with the invention, and suitable for use in the circuit arrangement of Figure l;

Fig. 2a is a partly sectionized view of a portion of the tube shown in Fig. 2;

Fig. 3 is a schematic wiring diagram of a polyphase rectifying device according to the invention.

Referring to Figure 1, the circuit arrangement shown therein is designed for alternately charging two storage batteries 4 and 5 requiring different charging voltages by means 0! rectified 56 current. The alternating current is obtained by means of a transformer 2, is rectified by means 01' a rectifier tube I, the charging circuits being selectively established by means of a switching device 3 and the currents regulated by rheostats 38 and 31. These devices and the circuits will be more fully described hereafter.

The gas-filled polyphase rectifier tube Ia suitable type of which is shown in greater detail in Figure 2has a hermetically-sealed envelope comprising a main chamber 90 and two extending arms 9I9I connected thereto. Within the main chamber 90 and in the upper portion there- 01' are two anodes 6 and I, whereas in its lower portion is an incandescible cathode 8; the arms 9I-9I contain anodes 9 and III respectively.

The transformer 2 has its primary winding II connected to a suitable alternating current source I2, and is provided with two secondary windings I3 and 99. The winding I3 has a center tap I4 directly connected through a conductor38 to the negative sides of the storage batteries 4 and 5. In addition winding I3 has two end taps I5 and I6, and two intermediate taps I! and I8. Winding 99 supplies the heating current for the incandescible cathode 8 and is provided with a center tap I9, and with two end taps 20 and 2I, the latter taps being connected through conductors 22 and 23 respectively to the two ends of the incandescible cathode 8.

such a manner that only one of the switches A and B can be closed at one time. The switches A and B serve to establish the necessary connections for charging batteries 4 and 5 respectively. The switch A has three arms 25, 26, and 21 having fixed heels 28, 29, and 30, and are rotatable to cooperate in the closed positionsof the switches with contacts 3|, 32, and 33 respectively.

The heel 28 is permanently connected through lead 34 and rheostat 36 to the positive side of battery 4, whereas the heels 29 and 30 are permanently connected through leads 34 and 35 to the anodes 9 and II! respectively. Contact 3| is connected through lead 39 to the central tap I9, whereas contacts 32 and 33 are connected through leads 48 and 4| to the end taps I5 and I6 respectively of winding I3.

thus controls the charging of The switch A battery 4 by means of rectified current obtained by the full-wave rectifier formed by anodes 9 and III with the cathode 8, the circuit for one phase half-wave being as follows: From end tap I5 through lead 40, switch arm 26, lead 34, anode 9, cathode 8, one of the leads 22 and 23, center tap I9, lead 39, switch arm 25, lead 34, rheostat 36 to positive side of battery 4; the negative side of the battery being permanently connected tap I4 of winding I3. During the other phase, the charging of the battery 4 takes place through the circuit starting from end tap I6 through conductor 4|, arm 21, lead 35, anode I0, incandescible cathode 8, and back to the central tap I I in the same manner as has been described for the first phase.

The switch B, which is used for charging the battery 5, is provided with three contact arms 42, 43, and 44, having heels 45, 46, and 41, re-

the anodes 6 and I respectively. Contact 48' is connected at 54 to lead 39 and thus to center tap I9 0! winding 99; whereas contacts 49 and 50 are connected through the leads and 56 to the intermediate taps I1 and I8 respectively.

switch arm 43, lead 52, anode 6, cathode 8, one of the leads 22 and 23, center tap I9, lead 39, switch arm 42, lead 5I, rheostat 31 to the positive pole of battery 5; the

the other phase the circuit is from intermediate tap I8, lead 56, switch arm 44, lead 53, anode I, cathode 8, and to the positive pole of battery 5 in a manner similar to the first phase. Thus it will be noted that for the charging of the highvoltage battery 4, a high alternating voltage is applied between the cathode and the high-voltage anodes 9 and I0; whereas for the charging of. the lower-voltage battery 5 a smaller alternating voltage is applied between the cathode and the low-voltage anodes 6 and 1. These alternative voltages are for example a thousand volts for the high-voltage anodes and 380 volts for the low voltage anodes. The current may be for example 15 amps. and 3 amps. respectively.

Of course other voltages and currents may be used, lying generally above 500 volts for the highvoltage anodes, for which the blocking voltage may go up to several thousand volts. age applied at the low voltage anodes generally lies under 400 volts and the currents rectified may reach a value 01' 100 amps. and more.

The rectified tube in Figure 2 consists of a vitreous envelope formmain chamber by means of metal rings 63 and 64 respectively. The rings 63 and 64 may be of chromium iron alloy and connected by leads I-IOI to suitable potentials for the purpose of material of the vapor in its non-vaporised form, for example a drop of mercury I02, is provided in the envelope.

Supported from the bottom of the main chamber by means of supply leads 65 and 66 is the incandescible cathode 8', which may be an oxide cathode. The supply leads 65 and 66 are connected to supply conductors 69 and I6 respectively through metal discs 61 and 68 sealed in the bottom of the vitreous envelope.

Supported from the top of the envelope by means of rods II are the two anodes 6' and I. The rods 'II are electrically connected to suitable terminals through metal discs I5 hermetically sealed in the envelope. Suitable discs for this purpose have been described in U. S. Patent 1,734,809.

Located at the end of the arms 6| and 62 and supported in a manner similar to that of anodes 6' and 1 are the high-voltage anodes 9 and I 0' respectively.

If required one or both pairs of anodes may be provided with enclosing screens to increase the blocking voltage. Such screens 83 are shown for the anodes 6' and I, their construction being fully described in the copending U. S. application Ser. No. 738,758, filed August 6, 1934.

The volt-- 'For example if the anodes I and 1' are used .for voltages up to 100 volts the screens can be omitted, whereas if they are used for voltages of more than 100 volts, screens are preferably provided. Similarly, for voltages of 500 volts anodes 9' and i0 require no screens, whereas for voltages of 1000 volts and more screens are preferably provided.

If desired, there may be also provided in the main chamber 60 and in the vicinity of. the cathode 8' (see Fig. 2a), an-auxiliary electrode 84, by means of which an auxiliary discharge may be created, the current for this discharge being supplied from a source of direct current (not shown). This discharge set up between the auxiliary electrode 84 and the cathode 8' due to its ionization effect, carries off the electric charges accumulating at the mouth of the arms 6i and 52, and which charges, unless so rendered ineffective, may seriously affect ignition between the cathode and anodes 9' and i0.

Thus the arrangement according to the invention permits one to obtain rectified currents having widely varying current and voltage values from a polyphase alternating current source by means of a single rectifier tube; the efficiency of the low-voltage rectification thereby being much higher than if the high voltage anodes were used also for the lower voltage.

Furthermore, the low-voltage anodes may be placed within the condensation chamber without requiring any increase in the size of this chamber or of the tube.

Although the embodiment described shows a two phase rectifier, three or six-phase rectification can be achieved in a similar manner. Also more than two sets of anodes may be provided in order to obtain more than two different voltages.

The device illustrated in Figure 3 comprises a transformer H I which transforms three-phase current supplied by a source H0 into six-phase current. For this purpose transformer Hi is provided with six star-connected secondary windings connected at a star point I20 and each having a terminal H2 and a tap H3. Terminals H2 supply the full secondary voltages of the transformer and taps H3 supply a fraction of these voltages. Terminals H2, taps H3, and the point I20 are connected to a change-over switch H4 indicated by a rectangle.

The device also comprises a six-phase rectifying tube H5 having six high-voltage anodes HG located in extendirig arms, and six mediumvoltage anodes H1 disposed within the main part of the tube envelope; all the anodes being connected to switch HI.

Tube H5 also has an incandescible cathode H8 disposed near the bottom of the tube and connected to the secondary winding of a heating transformer H9 having a primary winding connected to a suitable source of voltage. Connected with their negative terminals to switch H4 and with their positive terminals to a mid-point I30 on the secondary winding of transformer I I9 are two loads Hi and I22.

In a manner similar to Fig. 1, switch H4 has two positions. In one position anodes H6 are connected to terminals H2 and the high-voltage load l2l is in circuit, while taps H3 and load I22 are not in circuit. In the other position, anodes H1 are connected to taps H3 and the mediumvoltage load I22 is in circuit, while terminal H2 and load i2l are not connected.

Although I have described my invention in connection with specific examples and constructions, I do not desire to be limited thereto because obvious modifications will occur to one skilled in the art.

What I claim is:

1. A multi-voltage rectifying tube comprising an envelope having a condensation chamber and extending arms, a filling and a thermionic cathode within said envelope, a set of high-voltage main anodes disposed within said arms, and a set of medium-voltage anodes disposed within said condensation chamber above the entrance of said arms and nearer the cathode than are the high-voltage anodes, voltage anodes having at least the current carrying capacity of said high-voltage anodes.

2. In combination, a rectifier tube comprising an envelope having a condensation vessel and extending arms, a gaseous filling and a cathode within said envelope, a set of medium-voltage main anodes disposed in said condensation chamsaid mediumher and above the entrance of said arms, and a set of high-voltage main anodes disposed in said arms and at a comparatively great distance from the cathode, said anodes being adapted to selectively cooperate with said cathode to selectively rectify alternating voltages of greatly differing voltages, and means to selectively apply a medium alternating voltage to said first set of anodes and a high alternating voltage to said second set of anodes.

3. A multi-voltage rectifying tube comprising an envelope having a condensation chamber and extending arms, a thermionic cathode and a gaseous filling comprising a vapor within said envelope, a set of medium-voltage main anodes disposed within said condensation chamber above the entrance of said arms and adapted to provide rectified current at a voltage of several hundred volts, and a set of high-voltage main anodes disposed within said arms at a greater distance from said cathode than are the medium-voltage anodes and adapted to provide rectified current at voltages of several thousand volts, said mediumvoltage anodes having at least the current carrying capacity of said high-voltage anodes.

4. A multi-voltage rectifying tube comprising an envelope having a condensation chamber and extending arms, a thermionic cathode and a gaseous filling camprising a vapor disposed within said envelope, a set of high-voltage main anodes disposed within said arms, a set of medium-voltage main anodes disposed within said condensation chamber above the entrance of said arms and nearer the cathode than are the high-voltage anodes, said medium-voltage anodes having at least the current carrying capacity of said high-voltage anodes, and means to increase the blocking voltage of at least one of said sets of anodes.

5. A multi-voltage rectifying tube comprising an envelope having a condensation chamber and an extending arm, a gaseous filling comprising a vapor, the vapor pressure in said arm during operation being considerably less than in said condensation chamber, a thermionic cathode within said chamber, a medium-voltage anode within said chamber above the entrance of said arm and adapted to cooperate with said cathode to provide rectified current of more than one ampere at several hundred volts, and a. highvoltage main anode within said arm and at a greater distance from said cathode than is said medium-voltage anode, said high-voltage anode being adapted to cooperate with said cathode to provide a rectified current or at least one ampere at a voltage from several hundred to several thousand volts.

6. In combination, a rectifier tube comprising an envelope having a condensation chamberand extending arms, a gaseous filling and a cathode within said envelope, a set of medium-voltage anodes disposed in said condensation chamber, and a set of high-voltage main anodes disposed in said arms and at a comparatively large distance from said cathode, said anodes being adapted to selectively cooperate to transform polyphase alternating current of greatly difiering voltages winding having a high-voltage taps and low-volt-- age taps, a high-voltage load circuit for the highvoltage anodes; a medium-voltage load circuit for the medium-voltage anodes, and switching means to selectively connect the medium-voltage anodes to said low-voltage taps, and the highvoltage anodes to the high-voltage taps.

7. In combination, a rectifier tube comprising an envelope having a condensation chamber and her adapted to alternately secondary winding, said secding having lah-voltage taps and low voltage tape, a high-voltage load circuit for the anodes disposed within the arms, a low-voltage load circuit for the anodes posed within the condensation and a switching memconnect said low-voltage taps with the anodes provided in the condensation chamber, and said high-voltage tape with the anodes disposed in the arms.

JOHANNES GIJSBERTUS I MULDER.

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