US2050665A - Electrical device - Google Patents

Description

All@ 11, 1936' G. A. MATTHEWS ETAL 2,050,665

ELECTRICAL DEVICE Filed May 16, 1932 3 Sheets-Sheet 1 wuwwww @QmmllrJ I 3 Aug.l ll, 1936. y G. A. MATTHEWS E1- AL- 2,050,665

ELECTRICAL DEVICE Filed May 16, 1932 3 Sheets-Sheet 2 nnnnnnnnnnnnnnnnnnnnnnnnnn n.

w, @M w wx f G. A. MATTHEWS ET AL Aug. l1, 1936.

ELECTRICAL DEVICE 3 sheds-sheet 3 Filed May 16, 1952 W e Ma@ MM. f w, m

Patented Aung. 11, 1936 UNITED STATES PATENT oFFlcE ELECTRICAL DEVICE George A. Matthews, Royal Oak, and Ralph H.

Cook, Hazel Park, Mich., assignors 'to The Detroit Edison Company, Detroit, Mich., a corporation of New York Application May 16, 1932, Serial No. 611,674

12 Claims.

i or other analogous uses.

One of the important ses for our invention is in connection with so-called supervisory control systems. Our improved system Aof supervisory control is in many respects far superior to any other control heretofore used. It is particularly adapted for use in electric power distributing systems where the wires for the supervisory control are carried on the same poleslused forthe high tension lines. Our system employs a minimum number of Wires, is absolutely reliable under adverse conditions of operation and is provided With safety features which protect both the operators and the equipment from being subjected to high voltages resulting from lightning discharges or falling of high potential conductors across the control wires. However, it can be used without safety devices.

Among the objects of our invention are the following:

First, to provide selective remote operation of electrical equipment by the use of alternating current of a relatively low frequency, namely, to 500 cycles per second.

Second, to provide a system in which a plurality of frequencies may be sent over a metallically, inductively or statically coupled circuit and selectively segregated at the receiving end by apparatus which is electro-mechanically tuned.

Third, to provide a system unaffected by external electrical conditions and capable of using apparatus tuned within narrow limits to exact predetermined frequencies capable of transmit-v ting sufiicient power to not be adversely affected by changes in coupling capacity or inductance.

Fourth, to provide electro-mechanically .tuned apparatus of such sensitivity and selectivity as could not be obtained by electrical resonance alone.

Fifth, to provide a control system having receiving relays which are not affected by surges anjd lightning disturbances.

Sixth, to prevent faulty operation of the relays lby falling of high tension lines on the conductors used in the control system or by other outside electrical disturbances.

Seventh, to provide a system for remote control of line switches and other apparatus so designed as to prevent accidental operation by outside electrical disturbances.

Eighth, to simplify supervisory control systems thereby lessening the cost of installation without sacrice of dependability.

Ninth, to make available simplied transmitting and receiving apparatus mechanically and. electrically tuned to predetermined frequencies 5' and adjustable to different frequencies. The frequency band is' such that the coupling is effected without high-priced insulating devices and protective equipment.

'I'hese and other objects are attained by the 10 improved system hereinafter more fully described and illustrated in the accompanying drawings, wherein Figure 1 is an electrical diagram of a system embodying our invention;

Figure 2 is a perspective view of a receiver;

Figure 3 is a top plan view thereof; Figure 4 is a section on line 4-4 of Figure 3; Figure 5 is a transverse section on line 5-5 of Figure 3; l 20 Figure 6 is a view similar to Figure 4 showing a transmitter instead of a receiver;

Figure '7 is a diagram illustrating a plurality of sending and receiving units connected to a common transmission line for selective operation of apparatus from a remote point;

Figure 8 is a diagram illustrating a system for operating remotely a pole top switch mechanism;

Figure 9A illustrates a pole top switch mechanism; l V

Figure 10 is a perspective view of a portion of the operating mechanism of Figure 9;

Referring now to the drawings, Figure 1 shows a simple hook-up of a sending and receiving apparatus embodying our invention. A represents the sending apparatus, A' the receiving apparatus, and T the transmission line connecting the two. 'Ihe transmitter vA comprises a steel springer reed I0 projecting from an adjustable swivel block II and carrying at its outer end the 40 adjustable weight I2. The spring as mounted is. free to vibrate and for any predetermined setting of the adjustable weight I2 the spring has a definite frequency of vibration. The vibrating motion is known as isochronous motion. y

For vibrating the read IIl the transmitter is provided with a laminated electromagnet I3, the U-shaped yoke I4 of which is adjustably spaced from the reed. The coil I5 of the electromagnet is connected to a battery I6 through a spring 50 contact I1 which by bearing against a` cooperating contact I8 on the reed forms an interrupter, completing the circuit when thereed I0 is in the maximum displacement away from the electromagnet and in the neutral posiiton and breaking the circuit when the reed is in the maximum displacement toward the magnet. The circuit above mentioned includes the conductor i9 leading from the negative of the battery i6 to one side of the coil l5, the conductor 28 leading from the other side of the coil to the spring contact l1, the conductor 2i leading from the reed I8 to the switch 22, and the conductor 23 leading from the switch to the positive of the battery Il.v Thus by closing the switch 22 the electromagnet i3 is alternately energized and deenergized, thus setting the reed in vibration at a frequency corresponding to its fundamental vibration period as that may be calibrated by the Weight.

Cooperating with the vibrating reed i8 are two spring contacts 24 and 25 which are carried by the swivelblock il but insulated therefrom. These contacts are spaced so that the reed l0 alternately contacts with the same through the contact points 26 and 2l fixed on the reed. The contacts 24 and 25 are connected in circuit with the battery i6 through a; transformer 23. The primary coil 29 of the transformer has one terminal thereof connected by the conductor 38 to the spring contact 24, while the other terminal is connected by conductor 3l to the spring contact 25. 'I'he negative of the battery is connected to a center tap 32 on the primary by conductor 33. Thus a circuit through the primary of the transformer is alternately completed in opposite directions by the contacting of the reed H0 with the spring contacts 24 and 25. This generates an alternating current, the frequency of which is identical with the vibration period of the reed l0.

The secondary 34 ofthe transformer 28 is preferably designed to produce a higher voltage, which of course is at the' same frequency as the primary and this frequency may be transmitted to a remote point through any desired circuit whether this be coupled metallically, inductively or statically as is Well understood in the art. As shown, the transformer 28 is connected to the transmission line through a. high voltage insulating transformer 35 designed to protect the sending apparatus from any high tension current which might be impressed on the transmitting line from outside sources. The transmitting line T, las shown, a two-way circuit consisting of the conductors 36 and 31, although if desired a single conductor circuit might be used with ground connections.

At the receiving end of the apparatus the transmission line is connected through another high voltage insulating transformer 38. The receiving apparatus A is preferably of similar design to the transmitting apparatus A in that there is a vibratory reed 48 carried by an adjustable swivel block 4I and having at its outer end the adjustable Weight 42. An electromagnet 43 is arranged in an adjustably spaced relation to the vibratory reed and consists of a yoke 44 and coil 45. The coil 45 is in circuit with the secondary of the transformer 38 but a condenser 46 is placed in the circuit for the purpose of blocking off any direct current which might be imposed on the circuit as well as aiding in the tuning of the coil 45 to a xed frequency corresponding to that which has been transmitted from the sending apparatus. The receiver is preferably arranged with a coil 4l' surrounding the vibratory reed 48 in order to polarize the same. This coil is connected to a battery 68 by means of conductors d@ and 5GB.

Since the reed 40 is polarized it will be attracted and repelled by the frequency imposed on the electromagnet 43 and will thus tend to vibrate the reed 48 at exactly the same frequency as the incoming frequency. If the mechanical period of vibration of the reed is the same as the frequency "of the current in the electromagnet, the reed will be caused to freely vibrate at its fundamental vibration period.

Mounted on the swivel block 4l are the two spring contacts 5i and 52 arranged on opposite sides of the vibrating reed and adapted to alternately contact with the contact points 53 and 54 on the reed. The spring contacts 5l and 52 are connected to a relay 55, the circuit being as follows: Conductor 56 connects both spring contacts 5l and 52 with one terminal of the relay, while conductor 51 connects the reed 40 with the positive of battery 48 and conductor 58 connects the negative of the battery to the opposite terminal of the relay. 59 represents a normally open circuit adapted to be closed by the energization of the relay 55, the circuit including va. battery or other suitable power source and a signalling device 6l or other suitable electrical apparatus.

In the operation of the simplified control system as above described and illustrated in Figure 1, the closing of the switch 22 at the sending station operates to energize the signal device 6l at the receiving station which may or may not be at a remote point. 'I'his operation is effected by first setting the vibratory reed lll in operation through the electromagnet I3 and interrupter l 1. The reed vibrates at a denite period and through the spring contacts 24 and 25 sets up an alternating currentof a frequency corresponding exactly to the fundamental mechanical vibration. This frequency is carried through a transmission line T and is finally imposed on the electromagnet coil 45 of the receiving apparatus A. The vibratory reed 40-of the receiving apparatus being mechanically adjusted to have the same fundamental vibration as the sending reed I0 is caused to vibrate at its fundamental perod by reason of thefact that the electromagnet is electrically and magnetically tuned to the same frequency. Under these conditions the reed I8 lvibrates to such an extent as to complete the circuit' through the spring contacts 5| and 52 and energize the relay 55 which in turn completes the signal circuit 59.

The system as thus far described is shown in a simplied form for the purpose of readily understanding the fundamental principles underlying the invention. However, in its practical application it will ordinarily be used in conjunction with other electrical apparatus for obtaining the results desired in a supervisory control system. One of the advantages of our system is that the sending and receiving apparatus may be tuned very exactly to precise frequencies so that the receiver, for example, will not be affected byfrequencies differing as little as one cycle from that to which the receiver is tuned but will operate over a wide voltage range. Thus it is possible to independently operate a plurality of different instruments of different rfrequency over the same `transmitting line. 'Ihis is illustrated more fully in Figure 7 wherein the sending units A, B, C and D are all similar to the sending unit A previously described except that they are tuned to operate at different frequencies. For example, if the unit A generates a 70 cycle alternating current, the unit B may be adjusted to generate a 72 cycle current, the unit C a 'I4 cycle current, and the unit D a '16 cycle current. The corresponding receiving units A', B', C' and D' are also mechanically and electrically tuned to the same frequencies. Thus the units A', B', C' and D' are tuned respectively to 70, 72, '14 and 76 cycles per second. The sending battery I6 is connected to each of the respective sending units through circuits including the control switches 22a, 22h, 22o and 22d. Each -of the units is also connected in parallel to the insulating transformer 35 in the same manner as previously set forth in connection with Figure 1. At the receiving end of the system the units A'., B', C and D' are connected in parallel with the insulating transformer 38. Also the receiving battery 48 is connected through the relays 55a, 55h, 55e and 55d to the respective receiving devices in the same manner as previously set forth. It will be noted also that the telephone transmission line T is provided with suitable fuses 38 in accordance with well known telephone practice.

In the operation of the multiple unit system as shown in Figure 7, the operation of the switches 22a, 22b, 22e or 22d either simultaneously or successively will generate alternating current of predetermined frequencies and impose the same upon the telephone transmission line.

, Each of the frequenciesgenerated will be conveyed to each of the receiving devices A', B', C' and D but only the frequency which corresponds to the tuned frequency of the particular receiving device will cause the vibrating reed thereof to operate. Whenever the frequency of the particular receiver is imposed thereon, however, it will cause the actuation of the corresponding relay. Thus it will be observed that by means of our invention itis possible to use a single line of conventional type for selectively operating a series of dierently tuned receiving devices.

It is to be noted that control systems of the type heretofore described can be advantageously used on existing signal lines with no interference. In other words, no matter what use is made of the line it will not operate the vibratory reed devices of our invention unless the current of the precise frequency is imposed thereon. Our invention in its preferred form uses relatively low frequencies in the range 15 to 500 cycles per second. These low frequency values .create small inductive and capacity values in the line impedance, thus allowing considerable variation in the length and type of line which may or may not be connected to the lines used for the signalservice or remote control. The low frequency current permits the passage of the impulses through iron core transformers or static condensers, and therefore provides suitable means for high voltage insulation between the remote control equipment and the transmission line.

In the receiving apparatus as illustrated in Figure 1 it is noted that the vibratory reed 40 is polarized. There are several advantages to this polarization: First, the sensitivity of the receiving relay is increased due to the magnetizing forces of both the polarizing coil 41 and the electromagnet coil 45. Second, the air gap between the vibratory reed 48 and the electromagnet core 44 may be increased, thus preventing faulty operation due to currents of diiferent frequency which may be imposed on the coil 45. Third, the ampere turns may be so varied in the polarizing coil 41 that the reed 40 will cease to vibrate even the reed 40 is a at spring having at its free end when subjected toits critical frequency under certain conditions of voltage. The field due to the coil 45 will overcome the polarization effect of the coil 41, thus tending to cause the reed to vibrate at double its fundamental vibration pe- 5 riod. However., since the reed can not mechanically vibrate at this double frequency, the ultimate effect is to stop the vibration entirely. Therefore apparatus constructed in accordance with our invention can be made responsive not only to a single frequency but also to predetermined voltages at said frequency.

In .the broader aspects of our invention, however, it is not essential that the reed be polarized, it only being necessary to change the mechani-H-` cal vibratory period of the reed in order to compensate for the lack of polarity. Thus in the unpolarized device the receiving reed would not be identical mechanically with the transmitting reed.

To illustrate more fully, without the polarizing coil the reed will vibrate at double the frequency of the imposed electrical frequency on the electromagnetic coil. This is due to the fact that the reed is attracted by the electromagnet twice during each cycle. On the other hand, when the polarizing coil is used, the reed is attracted and repelled once during each cycle.

While the apparatus used in our improved system may be built in various forms, we have shown in Figures'2 to 5 a preferred construction of the receiver. It is to be noted that the swivel block 4| is mounted on a cylindrical post 18 secured in turn to a base plate 1I. 12 is an arm secured to the base plate in winch are threadedly arranged adjusting screws 18 and 14 which bear against the swivel block 4I on opposite sides of thev post 10. 'Ihus the air gap between the reed and the electromagnet may be readily adjusted. As shown,

40 the longitudinal slot 15 through which extends a set screw 16 for clamping the weight 42 to the spring.

The contact springs 5I and'52 are secured to the swivel block 4I by means of the screws 11 and 18 which extend through the clamping blocks 18, 80 and 8|. Suitable insulating strips 82 are inserted on opposite sides of the respective springs to insulate the same from the swivel block. The vibrating reed 40 is also insulated from the swivel base by an insulating strip 83 and is attached by' means of the screws 84 and 85. 81 is a rib extending upwardly from the base to which is attached a spool 88 containing the polarizing coil The coil surrounds the free end of the reed 5 The transmitter is preferably of similarstructural form to the receiver previously describedexcept that the polarizing coil is omitted and a third spring contact I1-is provided to form the inter- 60 rupter as previously described in connection with Figure 1. The transmitter is shown in section in Figure 6 and it will be observed that it is similar in general construction to the corresponding section of the receiver illustrated in Figure 4.

As heretofore stated, our improved system of supervisory control may be utilized for the operation of signals or switching devices. Figure 8 illustrates the invention applied to a system for operating remotely a pole top switch mechanism in a high tension electric transmission line.

Figure 9 represents diagrammatically the construction of the pole top switch mechanism itself.

As illustrated in Figure 9, 90 is a pole adapted to carry at the top thereof the high tension une overrunning clutch |4|.

9| which, for example, may be designed to carry 24 k. v. a. The two portions of this line 9|a and 9|b are respectively secured to the cross member 92 by supporting wires 93 and suitable'insulators 94. Mounted on the cross member 92 are two switch arms 95 and 96 adapted to swing about the respective pivot points 91 and '98. The switch arms carry suitable insulators 99 and |00 between the outer and inner ends thereof. The high tension line portions are connected to the outer ends of the switch arms 96 and 95 by the flexible conductors and |02. A suitable linkage mechanism for opening and closing the switch is employed and as shown this comprises the arms |03 and |04 extending transversely to the switch arms 95 and 96 and connected together by the link |05. |06 is an operating arm extending from the switch arm 95 and connected to the vertical actuating rod |01 which in turn is connected to the operating mechanism |09 located at a lower portio'n of the pole. |09 is a supporting arm projecting laterally from the pole at a point intermediate the operating mechanism and the pole top. The arm carries a housing |0 in which are arranged coil springs A| and ||2 adapted to react in opposite directions on the cross member ||3 carried by the vertical actuating rod |91. The operating mechanism |08 is shown as comprising an electric motor ||6 mounted todrive a worm wheel ||1 through worm ||8.

Any suitable form of mechanism may be employed at this point but, as shown in Figure 10, it is preferable to have a shaft |40 to which the worm wheel ||1 is connected through a suitable 'I'he shaft |404 carries at one end the crank |42 to which is attached the actuating rod |01. Through the shaft |46 the crank |42 is connected to limit switches |38 and |39. These switches as shown comprise the stationary contacts |43 and 44 and the respective cooperating contacts |45 and |46. The cooperating contacts are in turn formed on spring arms |41 and |48 which in turn are supported on the follower arms |49 and |59,r each of which ispivotally mounted on the -pivo-t shaft |52 and |53 are cams on the shaft |40 with the high portions |54 and |55 arranged 180 apart. Ihe followers |49 and |50 ride upon the respective cams |52 and |53 and the arrangement is such that the contacts |43 and |45 are closed when the crank is in the lowermost position and the contacts |44 and |46 are closed when the crank is in its highest position.

Beneaththe high tension line 9| the pole 90 is adapted to support an overhead telephone line which preferably consists of the two conductors |4 and I5. This line may be used for ordinary telephone .purposes and it may also be utilized in our system for the remote control of the pole top switch mechanism.

In the electrical diagram shown in Figure 8 the telephone line is represented by the reference characters |4 and ||5. i9 represents the sending station in which there is a telephone |20, a pole top opening switch |2| and closing switch |22. The sending station is coupled to the telephone line through the insulating transformer |23. Connected to the opening switch |2| is a vibrating reed transmitter |24 of the type previously described and connected to the closing switch |22 is a vibrating reedv transmitter |25 of a similar type. These two transmitting devices have reeds Vibrating at diiierent fundamental periods, thus generating in the transformer |26 alternating currents of diierent frequencies.

astuces |21 represents the receiving station for operatu ing the pole top switch mechanism |06. The telephone line is coupled to the receiving station through the insulating transformer |28. |29 and |30 represent vibrating reed receivers of the type heretofore described. Receiver |29 isvtuned mechanically and electromagnetically to respond to the frequencies generated by the transmitter |24 and the receiver |30 is correspondingly tuned t0 respond to the frequencies generated by transmitter |25. |3| is a relay operated by the vibration of the reed in receiver |29 and |32 is the corresponding reay for receiver |30. |33 and |34 represent respectively sealing-in relays for the opening and closing circuits respectively.

These relays are connected to the stationary contacts |43 and |44 respectively, and the limit switches |38 and |39. The cooperating contacts |45 and |46 respectively are connected together by a conductor |56 which leads to the relay |31.

The electric motor i6 is arranged in circuit with the operating battery |35 through the bridging contact |36 carried by the relay |31.

The arrangement described above and fully illustrated in Figures 8, 9 and 10 is such that upony the actuation of the receiver |29 the relay |3| is closed which in turn completes a circuit through relay |33, contacts |45 and |43 of limit switch |30 and relay |31. The closing of the relay |31 actuates the switch' |36, thereby connecting the.

motor H6 in series with the battery |35 and starting the motor. The closing of the relay |33 completes the circuit through relay |31 independently ofthe reay switch |3| so that upon release of the relay 3| the motor ||6 continues to operate. The motor thereupon drives the worm wheel ||1 and through the overrunning clutch 4| drives the shaft |40 and crank |42 from its lowermost position to its uppermost position. The movement of thecrank in turn operates the rod |01 and closes the pole top switch when the crank has reached the upper limit of its movement. The limit switch |30 through the cam |52 Withdraws the contact |33 and breaks the circuit through the relay |31. The deenergization of the relay |31 opens switch |36, deenergizing motor ||6.

It will be understood that in the above. dey scripto'n the closing of the pole top switch is dependent upon the actuation of the receiver |29 which in turn is responsive oniy to the particular frequency generated by the transmitter |24. Thus the operation of the closing switch |2| will close the pole top switch but any other electrical energy in the telephone line will have no eiect. For opening the pole top switch the operating switch |22 is actuated, energizing the transmitter |25 and generating a frequency to which the receiver,| 30 is tuned. As soon as the vibrating reed of receiver |30 is operated the relay |32 is closed and this in turn completes a circuit through relay |34, contacts |44 and |46 of limit switch |39 and reay |31, therebyvenergizing the relay |31. Thus in the same manner as previously described, the switch |36 is closed, the motor ||6 set in operation and continued in operation independently of the relay |32 by reason of the sealing-'in relay |34. The operation of the motor now causes the crank |42 to move from its uppermost position to its lowermost position, thus drawing downwardly on the actuating rod |01 and opening thepole top switch. The motor continues in operation -until the limit switch |39 reaches the point Where contacts |44 and |96 are separated by the cam |53 and thereupon the motor is deenergized.

Thus it will be observed that the mechanism disclosed in Figures 8, 9 and 10 may be used to open and close pole top switches by a controlling mechanism operated at a distant point.

What we claim as our invention is:

l. Invan electrical device of the class described,

' a vibratory reed, an electric contact point on said reed and a cooperating contact arranged within the amplitude o-f movement of said reed, an electromagnet operatively associated with said reed and the cooperating means for simultaneously/moving said reed and contact to adjust the distance between said reed and said electromagnet.

2. In an electrical device of the class described, a vibratory reed, contact points on said reed, a pair of contacts on opposite sides of said reed within the amplitude of movement of the contact points thereof, an electromagnet operatively associated with said reed and means for simultaneously moving said reed and contacts to adjust the distance between said reed and said electromagnet.

3. In an electrical device of the class described, a base, an electromagnet mounted on said base, a vibratory reed having the free end operatively associated with said electromagnet, a block supporting the fixed end of said reed and pivotally mounted on said base for moving said reed to adjust the distance between the free end of said reed and said electromagnet, contact points on said reed and cooperating electric contacts carried by said block and arranged on opposite sides of said reed and means for securing said block to said base in adjusted position.

4. In an electrical device of the class described, a base, an electromagnet mounted on said base, a vibratory reed having the free end operatively associated with said electromagnet, a block supporting the xed end of said reed and pivotally mounted on said base for moving said reed t adjust the distance between the free end of said reed and said electromagnet, electric contacts carried by said block and arranged on opposite sides of said reed, cooperating contact points on opposite sides of said reed, a bracket on said base adjacent said block and adjusting screws in said bracket engaging said block on opposite sides of the pivotal axis thereof.

5. A vibratory reed receiver comprising an electromagnet having a eld coil and adjacent pole pieces, a vibratory reed extending across, on the same side of and adjacent to said pole pieces, means for energizing said electromagnet with alternating current and means rendering said reed responsive to alternating current flow in said field coll of a frequency substantially identical with natural frequency of vibration of said reed, said means comprising a polarizing coil energized with direct current surrounding a portion of said reed. 4

f 6. A vibratory reed receiver comprising a base, a U-shaped electromagnet on said base, a vibratory reed having one end secured to said base and the other end extending across the open endr of said U-shaped magnet on the same side thereof anda polarizing coil surrounding the portion of said reed adjacent said magnet and having a substantial portion thereof outside of the magnetic circuit of said magnet, said polarizing coil when traversed by direct current operating.

a U-shaped magnet core on said base, an alternating current coil on said core, a vibratory reed having the free end extending across the open end of said U-shaped magnet core on the same side thereof,.a block supporting the xed end of said reed and pivotally mounted on said base for moving said reed to adjust the distance between the free end of said reed and said magnet core, a pair of electric contacts carried by said block and arranged on opposite sides of said reed, contact points on said reed, means for securing said block to said base in adjusted position, a polarizing coil surrounding a portion of said reed and having a portion of its circumference extending between the open ends of said U-shaped magnet core, means for energizing said polarizing coil with direct current, whereby said reed will vibrate at its natural frequency when alternating current of the'same frequency is supplied to the coil on said core, and an electro-responsive device connected through said contacts and contact points to a current source whereby the vibration of said reed will close circuits to energize the same.

8. A supervisory control system comprising a vibrating reed transmitter, a vibrating reed receiver located at a point remote from' said transmitter, said vibrating devices each comprising a magnetic core, a coil surrounding a portionof said core, a mechanically tuned reed operatively associated with said magnetic core and contacts operatively associated with said reed, said reeds being tuned to the same frequency of vibration,l said transmitter having a circuit interrupter operated by said reed and connected through said coil to a source of direct current,.a transformer, means operated by said reed and said contacts for alternately producing'in said transformer equal and opposite direct currents of the same frquency as the vibration period of said reed thereby generating an alternating current in said transformer, a telephone line having stations at the remotely spaced points where said transmitter and receiver are located, insulating transformers at each of said stations, one of said transformers being electricallya connected to said alternating current transformer of said transmitter, said receiver having the aforesaid coil thereof electrically connected to the other of said insulating transformers, a. condenser in series with said receiver coil for tuning the same to the frequency of said transmitter and a polarizing coil surrounding a portion vof the reed in said receiver to condition said reed for vibration at its normal frequency when the coil on said core is traversed by alternating current of the same frequency.

9. A supervisory control system comprising a vibrating reed transmitter, a vibrating reed receiver located at a point remote from said transmitter, said vibrating devices each comprising a magnetic core, a coil surrounding a portion of said core, a mechanically tuned reed operatively associated with said magnetic core and contacts operatively associated with said reed, said reeds being tuned to the same frequency of vibration said transmitter having a circuit interrupter operated by said reed and connected through said coil to a sourceof direct current, a transformer. means operated by said reed and said contacts for alternately producing in said transformer equal and opposite direct currents of thesame frequency ,as the vibration period -of said .red thereby generating analternatingcurrent in said transformer, a two wire telephone line including spaced stations adjacent said transmitter and receiver, insulating transformers at each of said stations, one of said transformers being electrically connected to said alternating current transformer of said transmitter, said receiver having th aforesaid coil thereof electrically connected to the other of said insulating transformers, a condenser in series with said receiver coil for tuning the same to the frequency of said transmitter and a polarizing coil surrounding a portion of the reed in said receiver to condition said reed for vibration at its normal frequency'when the coil on said core is traversed by alternating current of the same frequency.

l0. In a supervisory control system, the combination with a telephone line connecting telephone stations at spaced points, said telephone line being of the type having eective capacity and inductance which vary in accordance with conditions of use, of a vibrating reed transmitter, a vibrating reed receiver, said vibrating devices each comprising a U-shaped magnetic core, a coil surrounding a portion of said core, a reed of the same vibration frequency extending across and adjacent the open end of said U-sliaped core and a pair of contacts on opposite sides of said reed, said ltransmitter having a circuit interrupter operated by said reed and connected through said coil to a source of direct current,

a transformer connected through said contacts with a source of direct current to alternately produce equal and opposite direct .currents through said transformer and generate an alternating current, said transmitter and said receiver being located at widely separated points and adjacent said telephone line, an insulating transformer electrically coupling said generating transformer with said telephone line, a second insulating transformer electrically coupling said telephone line to said receiver, a condenser connected in series with said second insulating transformer and said receiver coil for tuning the latter to the frequency of said transmitter, a polarizing coil surrounding a portion of said receiver reed adjacent said U-shaped core and connected to a source of direct current thereby to condition said receiver reed for vibration at its normal frequency when the coil on said core is traversed by alternating currents of the same frequency, and an electro-responsive device connected through said receiver contacts to an electric current source forming a circuit adapted to be completed upon vibration of said receiver reed.

11. In a supervisory control system the combination with a telephone line connecting telephone equipment .at spaced points, said telephone line having variable capacitance and inductance in accordance with conditions of use, and insulating transformers for protecting said line against high voltage, said transformers being located at points spaced apart along said line, of an electro-mechanically tuned means electrically connected to said telephone line by one of said transformers for generating an alternating current of predetermined frequency Within 20 the range of 15-500 cycles per second, an electro-mechanically tuned means electrically connected to said telephone line by another transformer at a point spaced from the transformer of said iirst means and responsive to said 25 predetermined frequency and means operable upon the mechanical vibration of said last mentioned means for operating a' relay to close a working circuit.

12. In an electrical device of the class de- 30 scribed, a base, a U-shaped electro-magnet having two pole pieces iixed to said base, a block pivotally mounted on said base, a reed secured to said block having the free end thereof extending from said block across and on the same side 3 5 of both of said pole pieces, a pair of spring contacts secured to said block having the free ends thereof extending from said block in the same dlrection as said reed and on opposite sides thereof and means for pivotally adjusting said block to 40 'vary the spacing between said reed and said pole pieces and to maintain the same relation between said reed and said spring contacts.

GEORGE A. MATTHEWS. RALPH H. COOK

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