US1971711A

US1971711A - Electric current rectifier control

Info

Publication number: US1971711A
Application number: US578242A
Authority: US
Inventors: Gaudenzi Arthur; Kobel Ernst
Original assignee: BBC Brown Boveri France SA
Current assignee: BBC Brown Boveri AG Germany; BBC Brown Boveri France SA
Priority date: 1930-12-01
Filing date: 1931-12-01
Publication date: 1934-08-28
Anticipated expiration: 1951-08-28

Description

Aug. 28, 1934. A. GAUDENZ] ET AL ELECTRIC CURRENT RECTIFIER CONTROL Filed Dec. 1, 1951 Patented Aug. 28, 1934 raisin ATEN? ELECTRIC CUnnEN-r RECTIFIER CONTROL Arthur Gaudenzi,

Baden,

and Ernst Kobe],

Application December 1, 1931, Serial No. 578,242 In Germany December 1, 1930 Claims.

This invention relates to improvements in electric current rectifying systems utilizing a rectifier of the metallic vapor arcing type and more particularly to the provision in such systems of improved surge discharges.

When potential surges occur in an electric current rectifying system, one of the usual results is the occurrence of backfires which may cause serious damage to the system. It is, therefore, desirable that such surges be discharged by means other than the portions of the rectifier structure involved in the rectifying action and before reaching a magnitude such as would cause a backfire. Such means for discharging surges may include a spark, or arc, gap in which one of the'poles comprises a suitable portion of the rectifier structure and the other pole of which is an electrode extending into the rectifier into the zone of the greatest vapor density and the greatest accessibility to metallic ions. The resistance of such gap to the dischargeof surges is therefore low relative to the resistance to such discharge by way of the rectifying anodes. The

2 immediate breaking down of the gap is thus assured. If, therefore, a surge potential appears at any of the rectifying anodes, particularly when such anodes are operating, the spark gap acts immediately andthe surge potential is discharged in such time asto prevent establishment of a backfire. The transformer supplying the rectifier is most frequently the source of such excess potentials for the reason that it permits potentials to build up therein. 7

It is, therefore, among the objects of the present invention to provide means for discharging surges in an electric current rectifying system employing a rectifier of the metallic vapor type in such manner as not to affect the anodes of the rectifier employed in the rectifyingaction.

Another object cf the invention is to provide means for discharging surges in an electric current rectifyingsystem employing a rectifier of the metallic vapor type in which the discharge will take place before such conditions can arise in the rectifier as will cause a'backfiring action therein. Another object of the invention is to provide a special path for the discharge of excess potentials occurring in an electriccurrent rectifying system.

Another object of the invention is to provide an electric current rectifying system having a path for the discharge of excess potentials occurring in such system which path will more readily permit discharge of such potentials than the anodes of an electric current rectifying structure of the metallic vapor arcing type.

Objects and advantages, other than those above set forth, will be apparent from the following description when read in connection with the ac- 6O companying drawing in which:

Figure l diagrammatically illustrates an electric current rectifying system util 'ng an electric current rectifier of the metallic vapor arcing type in which means are provided for discharging abnormal potentials from the system by the provision of a discharge path not involving the anodes of the rectifier; and

Figs. 2, 3, i and 5, illustrate modified embodiments of the surge discharging path structure in an electric current rectifying system of the character above mentioned.

Referring more particularly to the drawing by characters of reference, the reference numeral 6 designates an alternating o i nt supply line connected with the primary winding 7 of a transformer. The secondary wi... o the transformer are connected to provide a neutral point and the terminals of the windings are each connected through a reactance 9 of low capacitance with one of a plurality of main anodes 11 of a rectifier structure of the metallic vapor arcing type which includes a container 12 and a pool of vaporizable material 13 such as mercury, insulated from the container and forming a cathode. The anodes and the cathode are enclosed within the container and are insulated therefrom. The anodes 11 are partially enclosed within arc guides 14; which are suspended thereabout in insulated relation therewith. A conductor 16 connected withthe neutral point of the secondary windings 8 and a conductor 1'? connected with the cathode 13 together with a load, herein represented by a resistance 18, form the circuit to which direct current is supplied from the rectifier.

Auxiliary electrodes 21 extend into the container 12 in insulated relation therewith into a Zone of a great vapor density and a great number of metallic ions within the rectifier to establish a relatively low resistance discharge path for such electrodes and to assure the breaking down of the gap between the electrodes and the cathode. Each of the electrodes is connected with one of the anode connections with the transformer secondary windings 8 through an ohmic resistance 22 which limits the current which may flow through the auxiliary electrodes. The auxiliary electrodes are thus arranged to form a path with the cathode 13 for the ready discharge of abnormal potentials from the connections between 11.0

the main anodes and the transformer secondary winding. The auxiliary electrodes carry a very small amount of current as determined by the resistance 22 and the voltage drop between the electrode and the cathode during the time the arc is flowing from the anode, to which such electrode is connected, and the cathode. The discharge of surges being determined by the capacitance and the reactance in the circuit and the auxiliary electrode connection having only an ohmic re sistance whereas the anode connection has a reactance therein, any surges appearing at the terminal of a transformer secondary coil will be discharged by way of the auxiliary electrode rather than by way of the anode.

The continuous passage of a small amount of a current through the auxiliary electrode, however, introduces a loss into the rectifying system which is undesirable. creased by the use of a second ohmic resistance 23, preferably of higher value than resistance 22, in series with the first resistance 22 as shown in Fig. 2. The resistance 23 is bridged by means 24, such as a glow tube permitting the flow of current therethrough as soon as a predetermined voltage has been reached. The occurrence of excess voltages therefore causes the tube to break down upon the occurrence of a surge which shortcircuits resistance 23. The use of two resistances in the auxiliary electrode connection with means for short-circuiting one of such resistances also increases the sensitivity of the arc gap.

The resistances 22 and 23 may be replaced

b condensers

26 and 27, as shown in Fig. 3, which operate to permit the passage of current therethrough upon the occurrence of excess potentials whereupon tube 24 will break down to permit the discharge of the excess potentials by way of electrodes 21.

If a plurality of electrodes are used, each of which is arranged adjacent to a main anode, the circuit conductors for all of the auxiliary electrodes may be extended into the rectifier container through a single insulating bushing.

The structure of a rectifying system may be fur ther simplified by using only one auxiliary electrode for a number of anodes as shown in Fig. 4 in which the electrode 21 is shown connected between the terminals of two of the transformer secondary winding coils through

resistances

31 and 32 and

glow tubes

33 and 34.

It will be understood that the same electrode may be connected with any number of anodes merely by the use of additional resistances and glow tubes in a manner similar to that shown in Fig. 4. The

resistances

31 and 32 limit the current which may flow through the auxiliary electrode. The voltage at which the glow tube will permit passage of current is preferably less than the maximum normal voltage of the transformer and the tubes may be such as to permit passage of current there-through in only one direction.

. The resistances and glow tubes shown in the connection of the auxiliary electrodes with the "j anodes in theembodiment of the invention according to Fig. 4 of the drawing may be replaced by condensers .36 and .37 as shown in Fig. 5. A number of condensers may be arranged in the connection of the electrode with each of the anodes, and one of which condensers may be bridged by a glow tube as shown in Fig. 3.

The present invention provides a path for the discharge of surges other than by way of the .main anodes, which path will permit the discharge of surges more readily than by way of the anodes.

Such loss may be de- Such result is due particularly to the absence of capacitance and reactance in the auxiliary electrode circuit and to the arrangement of the electrode in a zone of a great vapor density within the tank. The resistance to the discharge of the surges may be decreased by employing material for the auxiliary electrode which will permit heating thereof to about 2000 C. or above, or by coating the electrode with a material such as will increase the electron emission thereof.

Although but a few embodiments of the present invention have been illustrated and described, it will be apparent to those skilled in the art that various changes and modifications may be made therein without departing from the spirit of the invention or the scope of the appended claims.

The invention claimed is: a

1. In an' electric current rectifying system, an alternating current supply line, an electric current rectifier of the metallic vapor type having anodes subject to surges, a transformer connecting the anodes of said'rectifiw with'sa'id supply line, a reactance arranged in the connection of each of the anodes with said transformer, an auxiliary electrode connected with each of the anodes of said rectifier between the transformer and the reactance and extending into a zone of great vapor density within said rectifier, and means connecting said electrodes with the corresponding anodes of said rectifier to cause'dis charge of the surges therefrom more readily through said electrode than through the anodes.

2. In an electric current rectifying system, an alternating current supply line, an electric current rectifier of the metallic vapor type having anodes and a cathode forming a path for the discharge of surges, a transformer connecting the anodes of said rectifier with said .supply line, a reactance arranged in the connection of each of the anodes with said transformer, an auxiliary electrodeconnected with each ofthe anodes of said rectifier between the transformer and the reactance and extending into a zone of great vapor density within said rectifien'and ohmic resistances included in the connections of said electrodes with the corresponding anodes to cause discharge of the surges from the connections of the anodes with said transformer before discharge of such surges through the anodes.

3. In an electric current rectifying system, an alternating. current supply line, an electric current rectifier of the metallic vapor type having anodes and a cathode forming a path for the discharge of surges, a transformer connecting the anodes of said rectifier with said supply line, a

reactance arranged in the connection of each of the anodes with said transformenan auxiliary.

electrode connected with each of the anodes of said rectifier between the transformer and the reactance and extending into a zone of agreat vapor density within said rectifier, a plurality of ohmic resistances included in theconnection of each of said electrodes with the corresponding anodes to cause discharge of the surges through v an alternating current supply line, an electric current rectifier of the metallic vapor type having anodes and a cathode forming a path for the discharge of surges, a transformer connecting the anodes of said rectifier with said supply line,

,a reactance arranged in the connection of each of the anodes with said transformer, an auxiliary electrode connected with each of the anodes of said rectifier between the transformer and the reactance and extending into the zone of relatively great vapor density within said rectifier, a plurality of condensers included in the connection of each of said electrodes with the corresponding anodes to cause discharge of surges through said electrode before discharge of such surges through the anodes, and means adapted to permit the flow of current therethrough upon the application thereto of a predetermined voltage, said means being arranged to short-circuit one of each of said plurality of condensers, said condenser and said means forming a path for more readily discharging surges than the path including said anodes.

5. In an electric current rectifying system, an alternating current supply line, an electric current rectifier of the metallic vapor type having anodes and a cathode forming a path for the discharge of potential surges, a transformer connecting the anodes of said rectifier with said supply line, a reactance arranged in the connection of each of the anodes with said transformer, an auxiliary electrode connected with each of the anodes of said rectifier between the trans former and the reactance and extending into a zone of a great vapor density within said rectifier, ohmic resistances included in the said connection of each of the electrodes with the corresponding anodes to cause discharge of potential surges through said electrodes before discharge of such surges through the anodes, and glow tubes adapted to permit the fiow of current therethrough upon the application thereto of a predetermined voltage, said tubes being connected in series with said resistances and forming therewith and with said electrodes a path for more readily discharging surges than the path including the anodes.

6. In an electric current rectifying system, an alternating current supply line, an electric current rectifier of the metallic vapor type having anodes and a cathode forming a path for the discharge of potential surges, a transformer connecting the anodes of said rectifier with said supply line, a reactance arranged in the connection of each of the anodes of said rectifier, an auxiliary electrode arranged within said rectifier in a zone of a great vapor density therein, ohmic resistances severally connected with said anodes, and glow tubes connecting said resistances with the said electrode, said tubes being adapted to permit the flow of current therethrough upon the application thereto of a predetermined voltage, said resistance and said tubes forming a path more readily operative to discharge surges occurring in the system than the path including the anodes.

'7. In a system of the character described, an electric current rectifier of the vaporous type comprising an anode subject to impression of potential surges thereon, means comprising an electrode connected with said anode extending into a zone of relatively great vapor density within said rectifier, and means connected with said anode operable to divert discharge of said surges by way of said electrode.

8. In a system of the character described, an electric current rectifier of the vaporous type comprising a plurality of anodes subject to the impression of potential surges thereon, means comprising an electrode connected with said anodes and extending into a zone of relatively great vapor density within said rectifier, and 11 means connected with said anodes operable to divert discharge of said surges by way of said electrode.

9. In a system of the character described, an electric current rectifier of the vaporous type comprising a plurality of anodes subject to the impression of potential surges thereon, means comprising an electrode connected with said anodes, means included in the connections between said anodes and electrode operable to prevent flow of electric energy by way of said electrode at voltages below a predetermined value, and means connected with said anodes operable to divert discharge of said surges by way of said electrode when the potentials thereof exceed said predetermined Value.

10. In a system of the character described, an electric current rectifier of the vaporous type comprising a plurality of anodes subject to the impression of potential surges thereon, means comprising an electrode connected with said anodes and extending into said rectifier, means comprising glow tubes included in the connections between said anodes and said electrode operable to prevent flow of electric energy by way of said electrode at voltages below a predetermined value, and means connected with said anodes operable to cause discharge of said surges by way of said electrode when the potentials thereon exceed said predetermined value.

ARTHUR GAUDENZI. ERNST KOBEL.