US1996145A - Device for receiving high frequency currents superimposed on electrical power supply lines - Google Patents

Description

April 2, 1935. M CHIRQL 1,996,145 DEVICE FOR RECEIVING HIGH FREQUENCY CURRENTS SUPERIMPOSED on ELECTRICAL POWER SUPPLY LINES Filed Jan. 19, 1933 trical power supply systems, for actuating certain Patented Apr. 2, 1935 UNITED STATES PATENT OFFICE DEVICE FOR RECEIVING HIGH FREQUENCY CURBENTS SUPERIMPOSED ON TRICAL-POWER SUPPLY LINES ELEC- Application January 19, 1933, Serial No. 652,559 In France August ,24, 1932 5 Claim.

it has already been proposed to superimpose high frequency currents, particularly currents the frequency of which corresponds to that of a musical note, on normal supply currents in elecmembers or certain apparatus, usually relays, responsive to high frequencies and adapted to perform definite duties under the influence of such currents, for example the change of tarifi in multiple tariff meters.

Such receiving members or apparatus which are usually located in the low tension portion of the system, (whereas the superimposed currents may be fed into the high tension portion thereof) are, in general, adapted to operate normally when the voltage of the superimposed currents varies within certain limits; so as to provide for the possible increases or drops in the voltage thereof but such limits are necessarily narrow.

The object oi this invention is to make said apparatus operate normally within considerably wider limits. t

In the systems proposed hitherto, the superimposed currents act directly on the receiving member. which is usually a resonance relay connected across the supply circuit.

According to the invention, the addition of an auxiliary circuit enables any receiver of superimposed currents to respond to two influences simultaneously.

(a) To an influence dependent upon the voltage of such currents available at the input, as is normally the case;

(b) To an influence dependent upon the amperage of such currents in the low tension leads of the system, and due to the currents induced in the aforesaid auxiliary circuit.

As will be hereinafter explained, the action according to (b) increases as the terminal impedance of the low tension system decreases for the superimposed currents; it will also be seen that this is equivalent to saying: The action according to (b) increases as the action according to (a) decreases."

Consequently, the auxiliary circuit according to the invention acts as an auto-compounding circuit" for supplying the superimposed current receivers, and enables the total action of such currents to be maintained substantially constant, (1'. e. substantially independent of the local conditions of the receiver) A further object of the present invention is to prevent fraudulent tampering with a remotely controlled device for changing the tariff of a multiple tarifi meter.

example, currents of the frequency of a musical note) placed in series with the line as at 3, or in parallel as at 3', according to the method used for superimposing; 4 is a step down transformer by means of which the terminal impedance 6, which maybe of any kind, can be supplied with current by the source 2 through the low tension line 5 and 5'. l and 8 are respectively the condenser and the winding of a receiving relay, e. g. of the resonance type. I

According to the present invention and as illustrated in Figure 2, there are added to the elements illustrated in Figure 1, an auxiliary circuit comprising a transformer, the primary winding Hi of which is in series with the low tension leads and the secondary winding of which supplies the supplementary winding 9 located on the receiving relay. The windings 8 and 9 of said relay have entirely separate magnetic circuits which do not react on each other and the currents passing through them act in the same direction, and are consequently additive in their action on the moving members of the relay.

In Figure 3, the auto compounding auxiliary circuit still comprises the transformer l0-l l,

but its secondary winding ll supplies the coil 8 of the receiving relay directly, the additional coil 9 of Figure 2 being eliminated. A condenser I4 is inserted in this circuit, either to prevent the current from the mains from entering the receiver, or to tune the auxiliary circuit, or to bring into phase the superimposed current directly entering the coil 8, and the current supplied thereto by the transformer Ill-ll, or to carry out simultaneously all of the above enumerated duties, or finally for any other purpose which may be considered necessary. 7

According to Figure 4, the transformer l0-ll of the auxiliary auto compounding circuit is replaced by an auto-transformer l2l3, a portion of the winding of which aids in supplying the coil 8 of the receiving relay, the condenser it being retained or not.

Finally, inFigure 5the transformer lil-ii is again replaced by an auto-transformer i2i3, the whole winding of which is, in this case, used to aid in supplying the coil 8 of the receiving relay, the condenser M being again retained or not, and a condenser i5 being added, if necessary, across the coil 8 in order to increase the voltage across the latter.

If the voltage of the superimposed currents across the coil 8 remains stationary or retains a mean value during a fairly restricted period of variations, the ordinary known device of Figure 1 is suflicient to ensure the correct operation of the receiving relay. But for a transformer d of given characteristics, account must be taken of the fact that the limits of the period of variations of the voltage of the superimposed currents are essentially dependent on the value and the nature of the terminal impedance 6 fed by said transformer. In particular, such impedance may retain a normal value for the supply currents which is in keeping with the power of the transformer d, but at the same time if a disturbing circuit, illustrated in the drawing by the capacity ll and inductance i8, is connected to the system accidentally or intentionally by the subscriber with fraudulent intent, i. e. to prevent the change tariff device associated with the meter from functioning, the said impedance may fall to a value far below that which is normally provided for the superimposed currents; in the latter case a considerable increase of such currents supplied by the transformer loccurs and, asa result thereof, a greater voltage drop across the reactance of said transformer and the impedance of the lines 5 and 5'; this finally causes a decrease in the voltage of the superimposed currents available across the coil 8 of the receiving relay. While the disturbing circuit i7i8 must have a very low impedance; for the high frequency currents,

- it is evident t it must have a high impedance vice of Figure l, the superimposed currents which pass through either the primary winding iii of the transformer ld-i i, or the portion ii of the winding of the auto transformer i2 l3, induce, in said auxiliary circuit, currents, the value of which, for aiding in supplying the receiver, increases with the actual value of said currents, i. e., as the terminal impedance 6. decreases.

, continuous or damped, or are modulated or not at the transmitting end, or detected or not at the receiving end, etc.

In general, any addition to an auxiliary circuit, whatever may be its form or its structure,

placed either in the receiver or in thevicinity thereof, and the eflect of which is to produce on the moving members of the latter, an action of superimposed currents which increases as the terminal impedance of the supply mains decreases for their frequency, will be considered to fall within the scope of the invention.

Furthermore, such an auxiliary or auto com pounding circuit with respect to the receiver which is the object of the invention, will have no appreciable action on the normal supply currents.

I claim:

1. In a low frequency electric supply network comprising a high tension side on which currents of higher frequency are superimposed, a low tension side and a step-down transformer connecting said high to said low tension side, the combination with a relay including a winding shunted across said low tension side and responsive to said superimposed currents, of a second transformer having a primary winding mounted in series in the low tension side of said network and the secondary of which cooperates with the winding of said relay, said second transformer being adapted to induce in its secondary a current which increases proportionately to any decreases of the current flowing through said relay winding.

2. System according to claim 1 in combination with a winding connected to mid second transformer secondary and cooperating with said relay winding to compensate the decrease of current 4i;

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