US1861437A - High-frequency supply - Google Patents

Description

June 7, 1932. R. c CURTIS 1,861,437

HIGH FREQUENCY SUPPLY Filed March 12, 1929 Resonant Relay Conh'ol Devices INVENTOR Richard C.Curt1s ATTORNEY Patented June 7, 1932 UNITED STATES PATENT OFFICE RICHARD G. CURTIS, OF WILKINSIBURG, PENNSYLVANIA, ASSIC-NOR TO WESTING- HOUSE ELECTRIC & MANUFACTURING COMPANY, A CQRPOB-ATION OF PENNSYL- VANIA HIGH-FREQUENCY SUPPLY Application filed March 12, 1929. Serial No. 346,359.

This invention concerns means for supplying a high-frequency current to a distribution circuit.

Numerous control and protective systems have recently been proposed which make use of a high-frequency alternating current superposed upon conductors which also carry the relatively low-frequency power current of a distribution system. Two particular applications of systems of this type are found in protective systems for railway distribution circuits and remote control of streetlighting systems.

One of the outstanding diflic-ulties which is common to the systems of these types proposed heretofore is in the means for supplying the high-frequency control or protective current to the circuit conductors and it is the principal object of this invention to provide an improved method of, and means for, supplying such current to a distribution circuit of the usual type.

It is a further object of my invention to provide a system of the type described in which the necessary auxiliary equipment is insulated from the conductor of the system to which it is applied, so that it may be readily utilized in connection with high-voltage systems.

Another object of my invention is to provide a high-frequency supply which need be designed to withstand only a relatively low voltage since it is not to be electrically connected across the distribution circuit, in the usual manner, or to any point thereof.

A further object of my invention is to make provision for adjustment of the constants of the auxiliary circuit utilized to supply the high-frequency current, so that the impedance of the circuit traversed by the high-frequency current shall be a minimum.

Another object of the invention is to eliminate the auxiliary tuning equipment which has been used heretofore in similar systems.

5 t is well known, that in order to supply a high-frequency current to a distribution system, some form of inductive reactance in connection with capacitive reacta-nce is required .to feed the high-frequency current into the system and, at the same time, to prevent the flow of low-frequency current in the auxiliary supply circuit. It has been customary, heretofore, to place the condenser or reactance or both in direct connection with highvoltage power circuits.

In accordance with my invention,Iutilizea current transformer, the primary winding of which I connect in circuit with one of the conductors of the distribution system. The secondary winding is connected to the auxiliary supply of low-frequency control current. This transformer serves to insulate the auxiliary supply circuit from the high voltage of the distribution system. The reactor, which is necessary in such circuit, is connected across the transformer secondary and an auxiliary, high frequency generator is connected, in series with a blocking condenser, across a portion of the secondary winding of the transformer.

For a thorough understanding of my invention, reference must be made to the accompanying drawing, the single figure of which is a diagrammatic illustration of my invention.

Referring to the drawing, a distribution circuit is illustrated at 10 and is adapted to receive energy, in the form of alternating current, from any suitable source, such as the generator 11, through a power transformer 11. A plurality of load devices or control elements, such as a lamp 12 and a circuit breaker 13, are adapted to be controlled by means of a relatively high-frequency control current supplied to the circuit 10 from an auxiliary source, such as the generator 14. Controlling equipment, indicated schematically at 15 and 16, may be employed to control the operations of the load and switching devices 12 and 13. An example of such control means which is responsive to high-frequency currents will be found in the U. S. patent to Lunt, No. 706,575.

The primary winding of a current transformer 17 is connected in series with one conductor of the circuit 10. The secondary winding of the transformer is provided with a plurality of variable taps, and a variable reactor 18 is adapted to be connected across a portion of the secondary winding. The resecondary and the reactor with variable taps actance of the condenser 19.

is to make possible the adjustment of the inductive reactance attributable to the reactor 18, the generator 14:, the transformer 17 and the circuit 10, equivalent to the capacitive re- WVhen this adjustment has been effected, it will be understood that the circuit traversed by the highfrequency current will be of minimum impedance to such current and, that at the same time, a high impedance for the low-frequency current will be afforded, to prevent circulation of the latter through the auxiliary supply circuit.

The operation of the control equipment illustrated at 15 and 16 may be effected varying the speed of the generator let to supply current of the particular frequency necessary to accomplish the desired operation. The auxiliary supply apparatus may be disconnected as soon as opportunity has been given for the operation of the distant apparatus.

It will be apparent that the system of my invention makes possible a marked reduction in the cost of the equipment necessary to sup ply a higlrfrequency current to a distribution system, since it eliminates the necessity for designing the required apparatus to with stand the high voltages characteristic of modern distribution systems. An additional advantage characteristic of my invention is that, since the direct connection between the auxiliary apparatus and the high-voltage line is obviated, a degree of safety not attained heretofore is afforded the operators of the apparatus. I

Since alterations and modifications in the embodiment of my invention herein shown and described will doubtless occur to those skilled in the art, it isnot my intention to be limited to such illustrated embodiment except as necessitated by the appended claims.

I claim as my invention:

, 1. The combination with a main power circuit, of a series transformer having a primary winding connected therein for introducing a control current thereto, a shunting reactor variably connected across the secondary winding of said transformer, and an auxiliary, high-frequency generator and a blocking condenser variably connected in series across a portion of said secondary winding to provide a generator circuit which may be tuned to series resonance with the main power circuit.

2. In a high-frequency supply for controlling a distribution system, the combination with a series insulating transformer having a primary winding connected in series with a conductor of said system, of a variable reactor for shunting a portion of the secondary winding of said transformer to provide a lowimpedance circuit, and a high-frequency generator and a blocking condenser connected in series across a portion of said secondary winding.

3. A system for impressing a high-frequency control current upon a power circuit carrying power at commercial frequency comprising in combination, a high-frequency generator for supplying control currents of predetermined frequencies, a current transformer having primary and secondary windings interposed between the generator and the power circuit, said primary winding being connected in series with the power circuit, a condenser, means for variably connecting the generator and condenser in series circuit relation across the secondary winding of the current transformer to provide a circuit which may be tuned to series resonance with the power circuit, a variable reactor, and means for connecting the variable reactor across the secondary winding of the transformer to provide a low-impedance circuit to function as a by-pass to the generator circuit for the power current flowing in the power circuit.

4. A system for impressing a control current of predetermined frequency on a power circuit comprising a generator for supplying a high-frequency control current, a current transformer having its primary winding connected in the power circuit, a condenser disposed to be connected in series with the generator across a portion of the secondary winding of the current transformer, a reactor, means for connecting the reactor in shunt relation to the secondary winding to provide a low-impedance circuit to by-pass the power current and means for variably connecting the generator and condenser across the secondary winding of the current transformer to provide a generator circuit which may be tuned to series resonance with the power circuit.

5. A system for supplying control current of predetermined high frequency to a distribution circuit connected to a power source comprising in combination, a current transformer having its primary winding connected in the distribution circuit, a reactor connected in parallel-circuit relation to the secondary winding of the current transformer to provide a low-impedance circuit for power current, an auxiliary generator for supplying control current of predetermined high frequency, a condenser connected in series with the generator, and means for variably connecting the generator and condenser in shunt relation to the secondary winding of the current transformer to provide a seriesresonance circuit to cause the Voltage induced in the primary winding of the current transformer to be increased over the normal value produced by the auxiliary generator.

6. A system for impressing a control current of separate frequency on a power circuit comprising in combination, a generator for supplying control current of separate fre quency, a current transformer having its primary winding connected in the power circuit, a reactor variably connected to the secondary winding of the current transformer to provide a low-impedance circuit for passing power currents, a condenser, and means for variably connecting the generator and condenser in series-circuit relation across the secondary winding of the current transformer to provide a circuit which may be tuned to series resonance with the power circuit whereby the generator voltage is caused to be amplified through the functioning of the series-resonance circuit.

7. In combination, a transformer having primary and secondary windings, a generator and a condenser connected in series across the secondary winding of the transformer, and a variable inductance also connected across the secondary winding, whereby the generator circuit may be tuned to series resonance with a power circuit in which the primary winding of the transformer is disposed to be connected.

8. In a system for supplying high frequency control current to a power circuit comprising, in combination, a current transformer having its primary winding connected in the power circuit, an auxiliary highfrequency generator variably connected in series across a portion of the secondary winding of the transformer and a shunting reactor variably connected across the secondary winding, whereby the capacitive and inductive reactance of the circuits may be adjusted to a predetermined relation.

In testimony whereof I have hereunto subscribed my name this 9th day of March, 1929.

RICHARD C. CURTIS.

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