US1757900A - Device for impressing signaling currents on electrical powerdistributing lines - Google Patents

Description

May 6, 1930. M. CHIROL 1,757,900

DEVICE FOR IMPRESSING SIGNALING CURRENTS v ON ELECTRICAL POWER DISTRIBUTING LINES Filed Oct. 7, 1927 lnvenl'br M U/LimZ Patented May 6, 1930 UNITED STATES PATENT OFFICE MAURICE CHIROL, OF PARIS, FRANCE, ASSIGNORTO COMPAGNIE POUR LA FABRICA- TION DES COMPT EURS ET MATERIEL DUSINES A, GAZ, OF MONTROUGE, SEINE, FRANCE, A JOINT-STOCK COMPANY OF FRANCE DEVICE FOR IMPRESSING SIGNALING CURRENTS ON ELECTRICAL FOWER DISTRIBUTING LINES Application filed October 7, 1927, Serial No. 224,753, and in France October 26, 1926.

The present invention relates to a device enabling high frequency signaling currents to be superimposed on currents of industrial or low frequency supplied by electrical distributing systems.

low frequency current nor its dangerous effects are ever entirely annulled. In certain systems, however, and in certain cases, it is possible almost to annul the efiect of the power supply current by using shunts which resonate at the frequency of the power supply current, but, owing to the low frequency of said current, large condensers must necessarily be used.

The present invention enables the effect of 25 the supply current on'the signaling apparatus proper to be practically eliminated, by making use of devicestermed chokes which are tuned to the frequency of the signaling current.

According to a characteristic feature of the present invention, two electro-magnetic circuits are interposed between the signaling current emitting apparatus and the supply lines on which such signaling current is to be superimposed, such circuits being so arranged as to let through the low frequency supply current in order to produce two opposed fluxes of zero resultant whereby the effect of said current on the signaling apparatus is practically eliminated, whilst the signaling current is allowed to pass through one of said circuits which superimposes it on the distributing line, the other of said circuits having a choke device, which prevents the signaling current from flowing therethrough.

According to a further characteristic of the present invention, the two circuits above mentioned are coupled to the distributing line and signal emitting apparatus by means of'two transformers the primary windings of which are respectively inserted in the distributing line and signal emitting apparatus circuits, Whilst the two secondaries of said transformers each comprise a coil divided into two sections which are respectively inserted in the aforesaid electro magnetic circults.

The two sections of the secondary coil of the transformer which couples the signaling current'emitting apparatus'to said two electro-magnetic circuits are oppositely wound so that, when the power supply current flows through them equal and opposite fluxeswill be created whereby said power supply current will'have no efiect on the primary windingof the transformer coupling said electromagnetic circuits and thesignaling apparatus together.

According to 'another characteristic of the invention, the choke device inserted in one of said -electro=magneticcircuits consists in aninductanc'e and a capacity tuned to enter into resonance at the frequency ofthe signaling current and mounted in parallel in said electro ma'gnetic circuit.

According to a further form of embodiment of the present invention in order to eliminate more effectively the effect ofthe power supply current on the signaling apparatus and in orderto impress the signaling current more easily on the distributing line,

an inductance and a capacity tuned to enter into resonance'at the signaling frequency are mounted in series in the electro-magnetic circuit which does not include the choke arrangement, said inductance being identical to that of the choke device.

According to a final characteristic of the present invention enabling signaling currents to be impressed across two wires of adistributing line at difierent potentials, the distribution line is coupled to the electro-magnetic circuits above mentioned through a shunt entering into resonance at thesignaling current frequency and having a high impedance tothe low frequency power supply current.

The invention'will be more readily understood from the description about'to be made A 4! thereof with reference to the accompanying drawing in which:

Fig. 1 shows a circuit arrangement for impressing signaling currents on a conductor of a low frequency electrical power distributing line.

Fig. 2 shows a circuit arrangement for impressing signaling currents across two conductors under potential difference of a low frequency electrical power distributing line.

Fig. 3 shows a modified form of the circuit of Fig. 2.

Fig. 1 shows a modified form of the circuit of Fig. 1.

Turning to Fig. 1, 1 is a conductor of an electrical distributing system through which a current 1 flows; 18 comprehensively designates a current transformer of which 19 is the primary winning whilst the secondary winding is in two coil sections 5 and 7. The primary winding 19 is mounted in series with the conductor 1; comprehensively denotes a transformer the primary 13 of which is connected to an alternator 15 for producing the signaling current which is to be impressed on the conductor 1. The secondary of the transformer 10 is in two sections 11 and 12 which are oppositely wound and respectively connected to the coils 5 and 7. 1 1 is the magnetic circuit of the transformer 10; 16 and 17 are respectively a capacity and an inductance mounted in parallel and tuned to enter into resonance at the frequency of the current generated by the alternator 15.

This device operates as follows:

Under normal circumstances, the current 1 produces in the circuits 5, 11 and 7, 12, 16, 17 two currents of slightly different magnitudes owing to the presence of the inductance 17 in the circuit 7, 12. These currents produce in turn two fluxes of opposite sign in the magnetic circuit 14:. The windings 11 and 12 are suitably designed so that said fluxes shall be practically equal; consequently the resulting field in the magnetic circuit 1 1 is practically nil and no current is produced in the winding 13.

In order to emit signaling current, the alternator 15, connected to the winding 13, is started up. The current generated by said alternator, not being able to flow in the circuit 12, 7, 16, 17 owing to the choke effect of the circuit 16, 17, only flows through the circuit 11, 5 and induces in the winding 19 a current of the signaling frequency which is superimposed on the current 1.

Thus the current 1 of industrial frequency does not flow through the signaling current alternator 15, and the signaling current only flows in one of the electro-magnetic circuits which impresses it in the supply line 1.

I11 Figs. 2 and 3, an application of the present invention to superimposing a signaling current across two conductors of an electrical distribution system has been shown. In

Fig. 2, 20 is a generator of current of industrial frequency, 21 and 22 are two power distributing cables respectively connected to the terminals of the generator 20; 23 designates comprehensively a transformer the primary winding 24 of which is in series with the primary winding 25 of a second transformer comprehensively denoted by 29; the transformer 23 is the equivalent of the transformer 18 of Fig. 1. The secondary winding 26 of the transformer 29 is in series with an inductance 28 and a condenser 27. The condenser 27 and the inductance 28 are tuned with the leakage inductance of the transformer 29 in such manner that this latter has the minimum impedance at the high frequency of the current generated by the alternator 15. It has however a high impedance at the low frequency of the supply current generated by the alternator 20.

The device then operates as follows:

The potential difference between the cables 21 and 22 set up by the generator 20 is prac tically nil between the ends of the winding 24-, whilst it is practically a maximum between the ends of the winding 25 since the impedance of the latter has been purposely made high for the low frequency of the current generated by 20.

When the alternator 15 emits current of high frequency to which the two resonance circuits 16, 17 and 26, 27, 28 have been respectively tuned, the potential drop of such current is practically maximum between the ends of the winding 24 and nil between the ends of the winding 25. The consequence is that the high frequency current is easily impressed across the cables 21 and 22 whilst the current generated by the alternator 20 has no effect on the alternator 15.

In Fig. 3 the transformer 29 of Fig. 2 has been replaced by a condenser 30. This condenser is tuned with the primary coil 24 of the transformer 23 so that the impedance of the circuit 24, 30 shall be a minimum for the high frequency current produced by the alternator 15. Moreover the potential difference across the ends of the coil 24 due to the flow of the low frequency power supply current is practically nil as previously explained, whilst the potential difference across the terminals of the condenser 30 is then a maximum. In other respects, this device operates in similar manner to that of Fig. 2.

In Fig. 4 has been illustrated an improvement on the circuit arrangement of Fig. 1. In the arrangement of Fig. 1, the low frequency current flowing in the circuit 7, 16, 17, 12 must be out of phase with the low frequency current flowing in the circuit 5, 11, owing to the presence of the choke device 16, 17, so that the fluxes produced by the coils 11 and 12 can not exactly balance, from which it ensues that a resultant field must necessarily exist in ducing low frequency current in the winding 13 and hence affecting the signaling current alternator 15. Furthermore, the points of juncture of the coils, 5, 7 and 11, 12 are not absolutely at equipotential and a low frequency current will flow in their connecting wire. The arrangement illustrated in Fig. i remedies the defects by the provision in the circuit 5, 11 of an inductance 31, identical to the inductance 17 of the circuit 7 16, 17, 12, whilst, in series with said inductance 31, is mounted a condenser 32 in the wire 33. Said condenser 32 is so designed as to enter into resonance with the inductance 31 and the leakage inductances of the windings 5 and 7 at the frequency of the signaling current.

This device operates as follows:

The low frequency current flows through the cable 1 and the winding 19; it induces in the windings 5 and 7 a current which flows through the circuit 7, 17 12, 11, 31, for the current in the condenser 16 is practically negligible. Likewise practically no low frequency current flows through the condenser 32 which is now connected across two points at practically the same potential owing to the presence of the inductance 31. In consequence, the windings 11 and 12 being oppositely wound create two equal and opposite fluxes. The resultant of such fluxes is nil and hence no low frequency current fiows through the winding 13.

lVhen a current of signaling frequency is emitted, such current flows through the winding 13 which produces a flux in the magnetic 1- circuit 14; this flux in turn produces in the windings 11 and 12 respectively two electromotive forces which are equal and opposite. The electromotive force produced in the winding 12 cannot give rise to a current due to the choke circuit 16, 17. On the other hand, the electromotive force produced in the winding 11 easily gives rise to a current in the circuit 31, 5, 32 owing to the fact that the condenser 32 is in resonance with the inductance 31 and the leakage lnductances of the windings 5 and 11-,at the signaling current frequency.

The arrangement that has just been described can be used for superimposing signaling currents on electric supply lines either in series with the low frequency power supply current, or in parallel with the same.

I claim:

1. Device for superimposing currents of signaling frequency on a low frequency electric supply system comprising, in combina tion, a low frequency electric supply system, signaling current emitting apparatus, two electro-magnetic circuits inductively coupling said low frequency supply circuit and said signaling current apparatus together and both adapted to let through said low frequency current, means included in said electro-magnetic circuits for causing said low J frequency current to produce two opposed and practically equal fluxes whereby practically no low frequency current is induced in said signaling current emitting apparatus, choke means included in one of said electro-magnetic circuits for preventing the flow of current of signaling frequency therethrough and means in the other of said two electro-magnetic systems for facilitating the flow of current of signaling frequency therein.

2. Device for superimposing currents of signaling frequency on a low frequency electric supply system comprising, in combination,-a low frequency electric supply system, a signaling current emitting apparatus, two electro-magnetic circuits inductively coupling said low frequency supply circuit and said signaling current apparatus together and both adapted to let through said low frequency current, means included in said electro1nagnetic circuits for causing said low frequency current to produce two opposed and practically equal fluxes whereby practically no low frequency current is induced in said signaling current emitting apparatus, choke means included in one of said electromagnetic circuits for preventing the flow of current of signaling frequency therethrough and means in the other of said two electromagnetic systems for eliminating the phase displacement of the low frequency currents flowing in said two electro-magnetic circuits introduced by said choke means.

3. Device for superimposing currents of signaling frequency on a low frequency electric supply system comprising, in combination, a low frequency electric supply system, signaling current emitting apparatus, two electrounagnetic circuits inductively coupling said low frequency supply circuit and said signaling current apparatus together and both adapted to let through said low frequency current, means included in said electro-magnetic circuits for causing said low frequency current to produce two opposed and practically equal fluxes whereby practically no low frequency current is induced in said signaling current emitting apparatus, choke means included in one of said electro-magnetic circuits for preventing the flow of current of signaling frequency therethrough, and means in the otherv of said two electro-magnetic systems for concomitantly facilitating the flow of current of signaling frequency therein and eliminating the phase displacement of the low frequency currents flowing in said two electro-magnetic circuits introduced by said choke means.

l. Device for superimposing currents of signaling frequency on a low frequency elec tric supply system comprising, in combination, a low frequency electric supply circuit, signaling current emitting apparatus, two

electro-magnetic circuits inductively conpling said low frequency supply circuit and said signaling current apparatus together and both adapted to let through said low frequency current, means included in said electro-niagnetic circuits for causing said low frequency current to produce two opposed and practically equal fluxes whereby practially no low frequency current is induced in said signaling current emitting apparatus, twoidentical inductances respectivelymounted in said electro-inagnetic circuits, two capacities respectively mounted in parallel and series with said inductances in said electromagnetic circuits and adapted to enter into resonance With said inductances at the frequency of said signaling current, said parallel and series condenser and capacity arrangements respectively preventing and assisting the flow of signaling current through their respective electro-magnetic circuits.

MAURICE OHIROL.

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