US2088490A

US2088490A - Power translating device

Info

Publication number: US2088490A
Authority: US
Inventors: Slepian Joseph
Original assignee: Westinghouse Electric and Manufacturing Co
Current assignee: CBS Corp
Priority date: 1923-12-13
Filing date: 1934-12-14
Publication date: 1937-07-27
Anticipated expiration: 1954-07-27

Description

July 27, 1937. J. SLEPIAN ,0

POWER TRANSLATING DEVICE Original Filed Dec. 13, 1923' 2 Sheets-Sheet l FYgJ.

WITNESSES: INVENTOR Vr /Mz Jose oh Slepian July 27, 1937. J. SLEPIAN 2,088,490

POWER TRANSLATING DEVICE Original Filed Dec. 15, 1923 2 Sheets-Sheet 2 Fig.3. 42 w W154 Time Time v l x "#55 Volts Volts 'WITNESSES: INVENTOR V M n Jo; eph Slepian UNITED STATES PATENT OFFICE 2,088,490 POWER TRAN SLATING DEVICE Joseph Slepian,

inghouse a corporation of Pennsylvania December 13, 1923, Serial d and this application De- Original application No. 680,396. Divide cembcr 14, 1934, Serial No.

My invention relates to electric translating ap- 15 Claims.

paratus and it has particular relation to translating apparatus of the type utilized in inductive heating systems.

The present application is adivision of my copending application, Serial No. 680,396, filed December 13, 1923.

It is an object of my invention to provide inductive heating apparatus, the energy for which shall be supplied from a direct current power Another object of my invention is to provide inductive heating apparatus, of the type wherein alternating current of a frequency within the intermediate range is supplied to the heating coil, that shall be capable of excitation from a low frequency power source or from a direct current power source.

More specifically stated, it

invention to provide inductive is an object of my heating apparatus devoid of mechanical converters wherein the inductive heating coil is supplied with current of intermediate frequency while the power supply is either direct current or of low frequency.

According to my invention heating apparatus in which or the current of low alternating current of I provide inductive the direct current frequency is converted into the proper frequency by the operation of a plurality of mercury are discharge devices, the excitation of which is con.- trolled by grids or starting electrodes.

With the foregoing and my invention consists in the cults, and methods of operation illustrated in the acwherein,

claimed hereinafter and companying drawings,

other objects in view,

arrangements, cirdescribed and Figure 1 is a diagrammatic view showing an embodiment of my invention.

Fig. 2 is a diagrammatic view showing a modification of my invention.

Fig. 3 is a diagrammatic view illustrating the operation of the system in Fig. 2; and,

Fig. 4 is a diagrammaticview showing a modification of Fig. 1.

In the apparatusrshown in Fig.

showing curves shown 1, alternating current is supplied t6"an inductive heater 16 in the load circuit 4, comprising a shunt excited I from a direct current source direct current generator 14, through

transformer windings

5 and 6 and mercury arc discharge devices or rectifiers i and 8. The

transformer windings

5 and 6 are provided with end terminals l and H, respectively, and a common neutral terminal 12. The

end terminal H is connected to the heating coil Pittsburgh, Pa., assignor to West- Electric & Manufacturing Company,

200 of the inductive heater 16 through a capacitor 11, the other end terminal I0 being connected to the remaining terminal of the heating coil. The intermediate terminal I! is connected to the positive terminal l3 of the direct current source.

A stabilizing inductance l5 may be connected in series with the direct current source 4 to maintain approximately constant current flow from the generator independently of the changes in the circuit relations 'of the translating apparatus. The stabilizing inductor is connected, in the preferred practice of my invention, between the negative terminal 23 and the common junction point of the cathodes 28 and 2| of the discharge devices 1 and 8. A commutating capacitor 52 is connected between the terminals l0 and II of the auto-transformer 5-6.

The mercury arc rectifiers 1 and 8 comprise evacuated envelopes l6 and I1, respectively, having anodes l8 and 19, respectively, and mercury cathodes 28 and 2|, respectively. The anodes l8 and i9 are connected to the terminals l0 and II, respectively, of the

transformer windings

5 and 6. Each rectifier 1 and 8 is provided with a starting electrode 53 which is actuated by means of an ignition transformer 55 having a secondary winding connected between the ignition electrode 53 and the mercury cathode of the rectifier and having a primary winding which is connected to a source 56 of pulsating direct current through a distributor 51.

The distributor 51 comprises a plurality of annularly disposed contact members 58 which are alternately connected to two bus conductors 59 and 80, respectively. The latter are connected by means of

conductors

62 and 63 to proper terminals of the primary windings of the ignition transformers, the other terminals of the ignition transformers being connected to a common conductor 64 leading to one terminal of a battery 65 constituting the source of supply of the pulsating direct current. The other terminal of the battery 65 is connected, through an interrupter 66 by a brush 61, to a distributor arm 69 which is rotated by a motor not shown in the drawings. The distributor arm 69 alternately makes contact with the several contact members 58 leading to the respective ignition transformers and alternately starts the mercury arc rectiflers "I and 8.

The interrupter 68 consists of a pair of quickbreak contacts H shunted by condenser 12. One of the contacts II is mounted upon a flexible arm I3 which is biased to an open position by a spring 14. A toothed cam 15 is rotated at a high 55 speed and closes and releases the quick-break contacts 1| at a high rate.

The alternate closing and opening of the quickbreak contacts 1I sends a pulsating direct current 5 through the primary winding of the one or the other of the ignition transformers 55 during the short interval of the engagement of the distributor arm 9 with a contact member 58. The pulsating direct current induces a high potential in the secondary winding of the ignition transformers and impresses upon the starting electrode 53 a high unidirectional potential with respect to the mercury electrode causing a discharge therebetween. The asymmetric or unidirectional quality of the induced potential results from the quick interruption and the relatively slow establishment and building up of the current in'the circuit including the interrupter 66.

In the operation of the apparatus illustrated in Fig. 1, the control of the current fiow through the rectifiers is effected by the operation of the starting electrode 53. Assume that a current is flowing from the positive terminal I 3 of the direct-current source and the rectifier 1 is energized. The current divides at the middle transformer-terminal I2 into two portions, one portion flowing directly through the transformer winding 5, and the other'portion flowing through the transformer winding 6 and the load circuit I to the end terminal I 0. It then flows. through the rectifier 1 and the conductor 19 to the negative terminal 23 of the direct-current generator I4. The distributing arm 69 is at the same time in the position shown in the drawings. The commutating condenser 52 is charged to a potential corresponding to the direction of flow of current into the load, that is, opposite to the voltage pressed thereon by the direct-current source II.

In the course of rotation, the distributing contact arm 69 energizes the ignition transformer of the formerly non-conducting rectifier I, causing a discharge between the starting electrode 53 and the mercury cathode 2|. The rectifier 8 45 thereupon becomes conducting and the current from the direct-current generator I4 is diverted thereto by the commutating action of the discharge current of the commutating condenser 52, the current through the rectifier 1 being 50 simultaneously reduced to zero. The mercuryarc rectifier I thereupon becomes non-conducting and the circuit therethrough is interrupted, while the current now flows through the transformer winding in the opposite direction. This 55 cycle repeats itself alternately in accordance with the operation of the ignition device. By regulating the speed of the distributor-51, the frequency of the generated alternating currents may be controlled.

In the modification shown in Fig. 2 the fiow of current through a double wave mercury rectifier is controlled by means of grids disposed in the space current paths of the rectifier. The two anodes II! and I I6 of the rectiflers are connected 65 to the two end terminals III and II of a transformer having two

windings

5 and 6 and provided with a common middle terminal I2 leading to a positive terminal I3 of the direct current generator I4. The mercury electrode III of the 70 rectifier is permanently connected to the negative terminal 22 of the direct-current generator I4. I

Two grids III and I I! are provided in the two rectifier paths leading between the mercury Tl cathode H1 and the two anodes H5 and IIS, for

the rectifier arm II5 so controlling the rectifying action and conductivity of the paths as to utilize thedirect current flowing from the direct-current generator I4 to supply power to the inductive heating coil I52 which is connected to the two end terminals III and I I in an analogous manner to the coil 200, the coil I52 being connected to the terminal I I through a capacitor I53.

The control potentialis provided for the discharge device by utilizlng a master oscillator. The mercury cathode II! is connected through a biasing battery I to a common terminal 2 of two secondary transformer windings I43 and I leading through current limiting resistors I21 to the grids H8 and I I 9 respectively. 'The secondary windings I43 and I of the grid control transformer cooperate with a primary transformer winding I45 which is included in an oscillating circuit with a condenser 6. A threeelectrode tube I41 is connected in a circuit including a source of electromotive force, such as a battery I48, across the condenser I 46. The grid I49 of the three-electrode tube I I1 is connected, through a feed-back coil I50, to the filament and serves 'to produce sustained oscillations in the circuit including the transformer winding Ill and the condenser I46.

The system illustrated in Fig. 2 is particularly well adapted for producing high-frequency currents such as are utilized in radio applications or for certain industrial purposes such as induction furnaces. I have illustrated an induction furnace comprising a crucible I5I surrounded by an inducing coil I52 which is connected in'series with a condenser I 53 across the terminals III and I I of the

transformer windings

5 and 6.

To illustrate the operation of the system shown in Fig. 2, I ,have reproduced, in Fig. 3, oscillographic records obtained during the operation thereof. Curve I54 shows the voltage across as a function of time; curve I55 shows the voltage across the ,rectifler arm IIG as a function of time; curve I56 shows the voltage between the anodes H5 and H6 as a function of time; curve I51 shows the current through the transformer winding 5 and curve I58 shows the current through the transformer winding 6 as a function of time; and curve I59 shows the voltage between the grid H8 and the mercury cathode I I1 as a function of time. In determining the direction of the voltage in the above diagrams, it has been assumed that the voltage in the direction of the arrow I 60 from the middle terminal I2 through the anode H6, cathode I I1 and anode II5 back to the neutral terminal I2 is positive. In determining the direction of flow of current it has been assumed that a current flowing in the

transformer windings

5 and 6 in the direction from right to left, that is from the end terminal II to the end terminal I0, is positive.

As will be seen from the above-described curves, the voltage across the rectifier arms pulsates from a low value, corresponding to the voltage drop of the rectifier when the arm is conducting, to a full value corresponding to the opencircuit conditions. The current in the transformer winding 5 leading to the conducting rectifier arm increases arm is conducting, while the current through the transformer winding} leading to the nonconducting arm of the rectifier decreases. The voltage which appears across the two terminals III and II of the

transformer windings

5 and 6, and. which is also the voltage across the two during the period that the rectifier anodes H and H8, corresponds to the change in flux attendant upon the increase in the current of one transformer winding and the decrease of the current in the other transformer 5 winding, both effects adding to each other since the direction of the currents are opposite. As seen from the above diagrams the current flowing from the direct-current source is divided into two approximately equal portions pulsating around mean values. The sum of both currents is approximately constant and corresponds to the total current flowing from the direct-current sourc'e.

It may thus be seen that only approximately half of the current flowing from the direct-current generator 14 flows into the alternating-current load circuit. The energy corresponding to the other half of the direct-current flow is utilized in raising the potential across the load circuit to approximately twice the potential ofthe directcurrent generator, by a transformer action in the

windings

5 and 6. It is to this end that the

windings

5 and 6 are preferably arranged in inductive relation to each other although my system would also operate with two separate transformers or coils.

The apparatus shown in Fig. 4 is similar to the apparatus shown in Fig- 1 except that a transformer with separate coils 5-6 and ISO is substituted for the auto-transformer specifically shown in the latter view.

Although I have shown and described certain specific embodiments of my invention, I am fully aware that many modifications thereof are possible. My invention, therefore, is not to be restricted' except insofar as is necessitated by the prior art and b'y-the spirit of the appended claims.

I claim as my invention:

1. An electric heating system including an in- 40 ductor coil, a pair of arc rectifiers inductively coupled together by said inductor coil, means for successively rendering said rectifiers alternately conducting and non-conducting, and a condenser connected between the circuits of said rectifiers 45 for interrupting the current flowing in one rectifier substantially immediately after the other rectifier is made conductive.

2. In an electric induction furnace having an inductor coil the combination of a plurality of 50 grid controlled arc rectifiers, a capacitor, a capacitor charging circuit including one of said rectifiers, a capacitor discharging circuit including another of said rectifiers, and an alternating current circuit including said inductor coil common 55 to said charging and discharging circuits.

3. In an electric induction furnace provided with an inductor coil, the combination of a plurality of arc rectifiers, each provided with a grid for controlling the starting of current between 60 its cathode and anode, a capacitor, capacitor charging and discharging circuits controlled by said rectifiers, means arranged to produce in each of said circuits 2. countervoltage which is dependent on the current in the other of said circuits,

an alternating circuit including said inductor coil common to said charging and discharging circuits'.

4. Inductive heating apparatus including the combination of a current conductive means for inducing heating currents, a plurality of electric rectifiers, a capacitor, a capacitor charging circuit including one of said rectiflers, a capacitor discharging circuit including another of said rec- 75 tifiers, and an'alternating current circuit including said current conducting means common. to said charging and dischar ng circuits.

5. Inductive heating apparatus including the combination of an inductor coil for inducing heating currents, a plurality of electric rectifiers, a capacitor, a capacitor charging circuit including one of said rectifiers, a capacitor discharging circuit including another of said rectifiers, and an alternating current circuit including said inductor coil common to said charging and discharging circuits, the said inductor coil inductively coupling together said charging and discharging circuits.

6. In an induction furnace having a charge containing crucible and an inductor coil, the combination of a plurality of grid controlled arc rectifiers inductively coupled together by said coil, a capacitor, connections for connecting said capacitor with said coil to produce a substantially resonant circuit, a variable frequency source of supply for said grids, and means for varying said frequency so as to maintain said circuit substantially resonant. v

"I. In an induction furnace provided with an inductor coil, the combination of a plurality of arc rectiflers, each provided with a grid for controlling the starting of current between its cathode and anode, means for generating a control voltage for said gridameans for varying the frequency of said control voltage, a capacitor, ca-

pacitor charging and discharging circuits controlled by said rectiflers, means arranged to produce in each of said circuits a countervoltage which is dependent on the current in the other of said circuits, an alternating circuit including said inductor coil common charging circuits.

8. Apparatus for heating an element comprising an inductor coil for inducing heating currents to said charging and disin said element, a first discharge device for supplying current pulsations of one polarity tosaid inductor coil, a second discharge device for supplying current pulsations of the opposite polarity to said inductor coil and means independent of said coil for predetermining the frequency of said pulsations.

9. Apparatus for heating an element comprising an inductor coil for inducing heating currents in said element, a discharge device having a control electrode and a plurality of principal electrodes for supplying current pulsations to said inductor coil and means independent of said coil for impressing potentials between said control electrode and said. principal electrodes to predetermine the frequency of said pulsations.

10. Apparatus for heating an element comprising an inductor coil for inducing heating currents in said element, a first discharge device having a control electrode and a plurality of principal electrodes for supplying current pulsations of one polarity to said inductor coil, a second discharge device having a control electrode and a plurality of principal electrodes for supplying current pulsations of the opposite polarity to said inductor coil and means independent of said coil for impressing potentials between the control electrode and the principal electrodes of each of said discharge devices to predetermine the frequency of said pulsations.

11. Apparatus for heating an element comprising an inductor coil for inducing heating currents in said element, a discharge device for supplying current pulsations to said inductor coil and means independent of said coil and including a master oscillation generator for predetermining the frequency of said pulsations.

12. Apparatus according to claim 10 characterized by that the means for predetermining the irequency oi the pulsations includes a master osciliation generator common to both said discharge devices.

13. Apparatus for heating an element comprising an inductor coil for inducing heating currents in said element, a discharge device for supplying current pulsations to said inductor coil and means independent of said coil and including a master oscillation generator of the type incorporating a high-vacuum discharge device for predetermining the irequency of said pulsations.

14. Apparatus for heating an element comprising an inductor coil for inducing heating currents in said element, a discharge device for supplying current pulsations to said inductor coil quency of said pulsations.

device having a control electrode and a plurality 10 of principal electrodes for supplying current pulsations of the opposite polarity to trol electrode and the principal electrodes of each of said discharge devices to predetermine the ire- JOSEPH SLEPIAN.