US2029542A - Remote control system - Google Patents

Description

Feb. ,4, 1936. H. s. POLIN 2,029,542

REMOTE CONTROL SYSTEM Filed April 9, 1932 Tau: 3/

INVENTOR HE/FBL-R T 6. P01 //V BY- (P W W +M.

ATTORNEYS 55 en'tire --apparatus -may b Patented Feb. 4, 1936 UNITED STATES PATENT OFFICE REMOTE CONTROL SYSTEM of Delaware Application April 9, 1932, Serial No. 604,228

21 Claims. (01. 175-320) The present invention relates broadly to control apparatus for effecting a desired operation or sequence of operations in response to electrical impulses. More particularly the invention pertains to control apparatus of this character responsive to electrical impulses transmitted from a remote point.

This application is a continuation in part of my copending application Serial No. 578,608, filed December 2, 1931.

The control apparatus of the present invention distinguishes fundamentally from others of the class defined in its ability to respond to sudden electrical changes of extremely short duration. Employed for purposes of remote control the system obtains discrimination in this fashion without the necessity for selecting circuits, by utilization of control impulses which, although of large amplitude, are of such short duration and small energy content as to be without effect upon all but the most delicate electrical appliances.

The invention therefore provides a means of utilizing an electrical power supply line, such as a residence lighting system, While operating in its normal manner, as the impulse conducting medium for remote control operation. Applied in this fashionthe energy of the power line may be utilized to generate'the remote control impulses as well as toa'ctuate the controlled ap- 30'pa'ratus in response thereto.

During such-joint use of the power line conductors, the'functions of power supply and remote control'areeffected in mutualindependence.

The normal variations in 'line' voltage due to random fluctuationsof' the power lo'ad' are insufficient to afie'ct the control a aratus. On the other hand the" remote control impulses are of such'small energy content aridtransient character as to produce no observable eiiects upon or injury to the power-equipment "I he advantagesi-of a remoterontrol system possessing suchffeatureis'iare at once apparent. Inasmuch as" outlets from 'a residence lighting are already availabledn all vparts of a i buildingfltheobstacle;o f providing the requisite conductors for transmitting, the". control impulses is ponge obviated Flexibility is present in extreme degree in tliatythe; sending and controlled units maybe plu ed into] any of the lighting outlet sockets ior operatiombetweenany two 'pointsgof thebuildinge :Theentire control equip -ment'may'be completelydisconnected from the lightingsystem With-equal :facilit-y.:. That is, the "of a' portable character utilized for the most temporary expedient in providing remote control actuation.

The possible uses of a control system having these characteristics appear almost unlimited. In the home the apparatus may be employed remotely to switch a fan or the like on or ofi, to tune a radio set, or to regulate a furnace. In connection with the latter objective, regulation may be effected automatically by employing an electric clock or a thermostat to control the transmission of impulses.

The control system of the present invention when installed in one residence, or apartment will function independently of similar apparatus installed in other residences in the vicinity, or other apartments in the same building. This results from the fact that the meter installed by the power companies at the inlet from the feeder line to each residence or apartment, serves effectually to prevent control impulses applied to the lighting system in one residence or apartment from affecting similar apparatus located in another residence or apartment. The basis of this expedient may be applied generally to arbitrarily section oil a line for remote control purposes by. insertion of small inductances between line sections it is thus desired to isolate.

The invention is not restricted in its use to remote control between parts of a building, or even to the use of wires as a conducting medium for the control impulses. These may be transmitted by wireless waves in which event the controlled portion would be associated with suitable radio receiving equipment.

Aside from the field of remote control the invention is generally applicable for effecting mechanical operations in response to transient electrical current surges of short circuit magnitude operative over extremely small time intervals. A suggested use of this character isthat of lightning protection for power lines and the like. Current surges upon a line due to lightning.

employed as a diode 'by connecting its cathode with one side of the power supply system, a connection extending from the anode -.ofthe tube through an actuating element,.such as-a'relay,

to the other side of the power system. Usually Y it is found desirable to connect a condenser in shunt to the relay winding. The cathode may be heated from a local source, but preferably is energized directly from the supply system, as by connection of the filament in series with suitable resistance between conductors of the system. If the tube utilized is provided with a control grid this may be left free of electrical connection or floating".

The actuating mechanism employs in a second modification a thermionic tube having at least a y control grid in addition to its anode and cathode.

The cathode and anode, as before, are suitably connected with opposite sides of the power system, the latter through the relay winding or other actuating element employed. The control grid' maybe connected between a pair of identical impedances serially connected between the conductors of the power line, each impedance preferably consisting of a resistance in series with'a condenser.

The impulse transmitting mechanism in its simplest form comprises nothing more than a fixed condenser of suitable capacity value, asso- I elated with suitable switching means for con-- an explanation of the observed phenomena.

,In the drawing, Figs. 1 and 2 show modifications of the invention adapted for use in remote control on residence lighting and power supply systems.

Fig. 3 shows the actuating mechanism employed as a lightning protective device for electrical power and distribution systems.

Referring to Fig. l, conductors F'represent a feeder line extending from an electric light and power generating plant supplying electrical energy to consumers at a line voltage E. Tapped off from the feeder at various points are a number of branch lines 1-3 inc. each extending through a meter M to the oiflce, residence, apart ment, etc., of an individual consumer.

A remote control system in aceordanceyvith the present invention is associated with branch line I on the side oi the meter opposite to that of the feeder F. The controlled or actuating device comprises a space discharge device or thermionic tube V, here shown as of the three-element.type,

having its cathode-K connected atone terminal to one side of the line I, the opposite terminal of the cathode extending through variable resistance l, to the opposite side of the line for pro-- viding the heating current. From the anode? a connection extends through an actuating elementR, such as a telephone switching relay, and a variable resistance r: to the upper conductor of the power line. Connected in shunt to the relay winding is a fixed condenser (21. The control grid G is shown unidentinegiwith any portion of the system and is thus saidt'o be "floating".

The impulse sending device comprises fixed condenser C: the terminals of which extend to a switchS for connecting the condenser across line 8 in alternate polarity for successive connections.

' countered.

The switch may be of a manuallyoperated type. The drawing shows a rotary switch, adapted to be driven by any suitable means, manually or by a motor, brushes 5 and 6 of which connect to the condenser terminals. .The brushes contact with slip rings 7 and 8 to which rotary contacts 9 and iii are connected. Upon rotation of the switch, rotary contacts 9 and i0 contact with stationary contacts II and i2 connected to the respective sides of line 3. As a result of this arrangement it will be apparent that continued rotation of the switch reverses t e connection of the condenser terminals for su cessive contacts.

The observed operation of the control system is that connecting the fixed condenser C2 between conductors at any point of the lighting system causes the relay R of the actuating circuit, wherever located, to release and then reoperate after a brief interval. If the switch is operated intermittently at a rate not less than The observed operation of the system appears to result from the character of the transient,

electrical disturbances caused by bridging condenser C2 across the line. Toexplain this, assume for the momentthat the feeder line F supplies direct current at a line voltage E. With switch S in the position shown, and after steady state conditions have becnestablished, a constant cur rent will flow through the winding of relay R equal to the ratio of the line voltage to the total resistance of the relay circuit including 1': and

.the space path resistance T0 of the tube.

Consider now that condenser C2 is fully'discharged and that switch S is advanced until rotary contacts 9 and I ll make contact with stationary contacts II and i2- respectively, thereby connecting the condenserCn across the line. At

the instant of connection, condenser Ca acts as a momentary short circuit on the line, instantly reducing the line voltage E1 across the relay circuit momentarilyto zero. As condenser C2 thereafter charges up,- the voltage E1 across the tube and relay circuit rises in substantial correspondence with the voltage at the condenser terminals.

ultimately resuming its normalvalue of E when the condenser Cris fully charged.

As is well-known the sudden bridging of condenser Ca across the line constitutes a shock excitation of the power line and associated elements. This sets up transient electrical disturbances which in general die out in exponential relation to time. The rate of decay is determined by the electrical constants of the system, resistance, inductance and capacity including that of condenser C2.- In a residence lighting system the decay period may be of relatively long duration owing to the low damping resistance en- It results therefore, that although the drop in line voltage El across the relay circuit is practically instantaneous, an appreciable time interval ensues before it builds up exponentially to its normal value E.

The sudden drop and more gradual rise of the line voltage E1 produces a corresponding variation in the flow of space current through tube V, due to the fact that the relay circuit is rendered almost reactionless by proper selection of the capacity value C1 in shunt to the relay winding. The drop in space current causes the relay current to decrease below its release value, the period of decay being expedited to this end by the accumulated charge on condenser C1 equal to the normal voltage drop across the relay winding.

The building up of the relay current to its normal value is more gradual than the building up of the line voltage E1 due to the presence of condenser G1, which, practically discharging during 1 the decay period, substantially short circuits the relay Winding upon resumption of current flow in the space path of the tube. It is not until the condenser (31 becomes charged to an appreciable potential that any considerable current again flows through the relay winding. This condenser charge accumulates slowly at first due to the excessively high space path resistance of the tube at low anode potentials. Inasmuch as the operating current of the relay is considerably higher than its release value, the period of reoperation is delayed to this extent by the additional time required for the current to attain this higher operating value.

In view of the fact. that the control grid G of tube V is maintained free of electrical connection, i. e. "fioating, any negative charge accumulating thereon will of course afiect the operation of the relay circuit. It has been experimentally observed that a grid left free or floating" obtains a negative potential, increasing in magnitude, as the anode potential of the tube is reduced to zero. This results from the fact that low values of anode potential are insufficient to draw all of the electrons past the grid, so that a number find lodgment there to establish a negative biasing potential on the grid. This, of course, reduces the magnitude of space current for a given positive potential applied to the anode.

This effect has been observed to influence noticeably the operation of the system of Fig. 1, upon continued rotation of switch S for an appreciable time interval at such speeds as to maintain low average po ential between cathode and anode of tube V. Upon stopping the switch it has been observed that the relay does not reop erate for a matter of 10 to 15 seconds thereafter for the particular apparatus employed. This represents the time required for the grid charge to leak off to the anode following resumption of the normal line potential E. That the efiect noted is due to an accumulated negative charge on the grid is demonstrated by the fact that grounding the grid, as by touching it, produces immediate reoperation of the relay.

This same action occurs although in less degree even for an isolated connection of condenser C2. Prior to such connection a cloud of electrons is being impelled from the anode past the grid at a. definite average velocity determined by the normal anode potential. Bridging condenser C: removes the irnpelling force almost instantaneously, thereby permitting a number of electrons to find lodgment upon the grid to establish there a negative potential which leaks off slowly upon resumption of the normal line voltage.

It will be observed that the several factors recited, act cumulatively to reduce the relay current rapidly below its release value and to retard its subsequent building up to its much higher operating value. As a consequence the almost instantaneous short circuiting eiiect due to connecting condenser C2 is magnified into an interval of considerable duration during which the relay current is maintained below its release and reop erate values, such intervals proving ample for the relay mechanically to efiect release followed by reoperation for each isolated bridging of the condenser. I

The system of the present invention is thus enabled to detect instantaneous changes in line voltage by its instantaneous electrical response to such changes followed by an automatic delay in returning to normal, sufficient to enable the actuating element, i. e. relay R, mechanically to respond to the change.

By proper proportioning of the inductance and capacity in the relay circuit RCl, satisfactory operation will be obtained upon replacing the three-electrode tube V employing the floating grid with a true diode or two-element tube having only a cathode and an anode connected as shown.

In View of the foregoing it is now apparent why continued rotation of switch S above a certain critical speed maintains relay R in its released condition. The line is capacitively short circuited by condenser C2 with such rapidity that the relay current does not have opportunity to build up to its operating value between successive connections of condenser C2.

Thus far the explanation has been restricted to operation of the system upon direct current lines. It has been observed to function equally well for alternating current supply. Assuming the line voltage E, Fig. 1, to be the usual Gil-cycle alternating current supply, the resultant space current flowing through tube V will comprise a succession of uni-directional pulses corresponding to the alternate half-waves of the impressed line voltage E. The relay current, however, does not pulsate between zero and a maximum value in the same fashion as the space current, owing to condenser Cl discharging into the relay winding during intervals when the line voltage renders the tube anode negative relative to its cathode. As a result of this action the relay current comprises a steady component, of magnitude sufficient to maintain the relay operated, together with a superimposed ripple current.

The action of the current in the relay winding in carrying over from peak to peak of the impressed alternating voltage in this fashion, is based upon entirely different considerations from its reduction below the release value due to bridg-.

ing condenser C2. In the one instance we are dealing with a so-called steady state condition due to a cyclically varying applied potential,

whereas in the other instance we are dealing with a purely transient phenomena caused by shock excitation of the system. In the case of the alternating current supply, the rectified volt; age applied to the relay circuit RCl is analyzable into a steady component with a superimposed 60-cycle alternating voltage. This is clearly a steady state condition to which the circuit R--C1 presents a true alternating current impedance, and one which does not introduce the transient action ascribed to condenser Cz.

Upon establishment of steady state conditions, the alternating current potential does not permit a negative biasing voltage to be established on the control grid, inasmuch as electrons impinging thereon are impelled by the applied voltage to leak off continuously either to the cathode or the anode, whichever happens to be negative relative to the other at any given instant. Here again the action distinguishes fundamentally fromthat due to an instantaneous removal of the force impelling the'electron stream, as by capacitively short circuiting the line with condenser C2.

In the case of the alternating current supply, the relay may of course be released in the same fashion as was described with reference to direct current. An isolated connection of condenser C2 to the line will cause the relay to release and reoperate, whereas intermittent connection of the condenser by rotation of switch S. will maintain the relay in its released condition.

The action occurring here is easily understood if switch S is rotated synchronously with the applied alternating current voltage in such phase relation as to bridge condenser C2 across the line during a portion of each cycle that the current is building up in the space path of the tube. This will have the effect of practically eliminating the normal pulses of space current,-

so that the average current flowing through the tube will be practically nil. Synchronous rotation of the switch in this manner is quite simply effected by mounting the rotary switch contacts upon the shaft of a synchronous motor, such as is employed in electric clocks.

It has been found in practice that it is not necessary to relate rotation of the switch to the phase of the applied potential in the manner stated. Random bridging of the condenser will sufllce provided the speed of rotation is sufiiciently high.

In view of the foregoing explanation it will now be understood how the conductors of the residence lighting system may be utilized simultaneously for remote signaling control and power supply purposes, mutually independent of one another. The control system requires for its operation an instantaneous reduction in line voltage to an excessively low value, in order to establish the effects upon which action of the system depends. In normal operation of the line for power supply purposes, the line voltage seldom changes more than a few volts, insufilcient to affect the relay circuit. In general the power load is resistive and inductive rather than capacitive, hence no action is obtained from the power load analogous to connection of condenser G2. On the other hand the large charging current taken by condenser C2 is of such short duration,

and of such small total energy content, as to produce no observable eifects upon the power line equipment.

In order to enable those skilled in the art to practice the invention, the following electrical values and apparatus have been found to produce satisfactory operation as applied to the usual residence lighting and power supply systems:

Condenser C2=1 to 3 microfarads Condenser 01:1 microiarad Relay R=Western Electric Co. alternating current telephone relay, A 8.

Tube V=National Union 12-11 The modification of Fig. 2 differs from that of Fig. 1 principally in that the control grid G is connected to both sides of the line 3 through identical impedances, each comprising a condenser Ca in series with a resistance R3. this arrangeinent the control grid G is normally maintained at a positive{ potential relative to its cathode equal to one-half the line voltage. Upon bridging the actuating capacity C2 across the line, condensers C: commence to discharge through the relatively high resistances R3, of

With

the order of 100,000 ohms each. This causes the grid potential to be reduced instantaneously to zero relative to the cathode. The resultant decrease in space current is suflicient to release relay R.

It has been found that the values of the various resistances and capacities need not be particularly precise, but a balance between all units involved is preferable. That is, the resultant capacity of the condensers C3 in series should be approximately equal to the capacity of the actuating condenser C2. Condenser C1 bridging the winding of relay R is not required with this circuit. Performance is improved by its addition, however.

An analogy in operation between the Fig. 1 and the Fig. 2 circuits is to be found in the negative potential applied to the control grid in each instance. Whereas in the Fig. 1 modification the negative grid potential is accumulated from the electronic stream, in the Fig. 2 modification it is positively applied from the line.

Capacity C1 need not comprise a distinct condenser unit. but may in fact constitute the distributed capacity of the winding of actuating element R suitably wound to this end.

In the circuit of Fig. 3 the control apparatus is employed for protection purposes on a power line. Conductors 30 extend to generator E to be protected, while conductors 3| extend to a power transmission line exposed to short circuits, lightning, etc. Conductors 30 normally extend through contacts 32 and 33 of a plunger type relay or circuit breaker R to conductors 3|. The relay is normally energized, in the manner described, by the space current of tube V supplied from source E.

If now a transient of short circuit magnitude originates along lines 3|, the resultant interruption of space current 'in tube V will momentarily deenergize relay R in the 'manner described. whereupon spring 34 will withdraw plunger 35 until resilient pin 36 engages lug 31 to lock the plunger in its released condition. The release of plunger 35 opens the line at contacts 32 and 33. After the line trouble is cleared the circuit breaker is reset manually-in the usual manner.

In the case of high tension lines, the control apparatus may be located in an auxiliary low voltage circuit, coupled inductively or capacitively to the high tension lines, as by paralleling the high tension system with a short section of the auxiliary circuit. Operation of the control apparatus would of course be then arranged to open the high tension lines. 1

I claim:

1. Control apparatus comprising a space discharge 'device including an anode and a cathode connectedrespectively to opposite conductors of an electrical power supply line, said tube having a control grid connected through high impedance to at least one said conductor and actuating means interposed in said anode connection responsive to interruptions in the space current of said device.

2. Control apparatus comprising a space dis charge device having an anode and a cathode connected respectively to opposite conductors of an electrical power supply line, and a grid connected to at least one said conductor through high impedance, means energizing said cathode, and a relay shunted by capacity interposed in the anode connection of said device, said apparatus responding to transient electrical disturbances of short circuit magnitude affecting said power line.

4. Control apparatus comprising a space discharge device having a cathode connected to at least one conductor of an electrical power supply line, an anode connected with an opposite conductor thereof, and an interposed grid maintained free of electrical connection, means energizing said cathode, and actuating means interposed in said anode connection responsive to interruptions in the space current of said device.

5. In combination, an electronic tube having a control grid connected through impedance with opposite conductors of an electrical power supply line, and a cathode connected with at least one said conductor, whereby the space current of said tube responds to potential variations of said line.

6. In combination, an electronic tube having a control grid connected through series resistance and capacity with opposite conductors of an electrical power supply line, a cathode connected with at least one said conductor, whereby the space current of said tube responds to potential variations of said line, and an anode having in circuit therewith an actuating element responsive to interruptions of said space current variations.

'7. In combination, an electronic tube having a control grid connected through series resistance and capacity with opposite conductors of an electrical power supply line, a cathode connected with at least one said conductor, whereby the space current of said tube responds to potential variations of said line, an anode having in cirouit therewith an actuating element responsive to said space current variations, and means including a condenser for capacitively short circuiting said line to actuate said element.

8. In combination, an electronic tube having a cathode and an anode connected respectively with opposite conductors of an electrical power supply line, and a control grid connected to impedance, the latter connected between said conductors whereby the space current of said tube responds to potential variations of said line.

9. In combination, an electronic tube having a cathode and an anode connected respectively with opposite conductors of an electrical power supply line, and a control grid connected to impedance, the latter connected between said conductors whereby the space current of said tube responds to potential variations of said line, and actuating means interposed in said anode connection responsive to said space current variations.

10. Electrical control apparatus comprising a space discharge device including an anode and a cathode, means energizing said device, actuating means responsive to the flow of space current in said device, and means includinga condenser for momentarily short circuiting said energizing means thereby to interrupt said space current and effect response in said actuating means.

11. Electrical control apparatus comprising a space discharge device having an anode and a cathode, a. potential source for energizing said device, actuating means responsive to the flow of space current in said device, and means including a condenser for capacitively short circuiting said potential source to eiiect response in said actuating means.

12. Electrical control apparatus comprising a space discharge device having an anode, a cathode and an interposed control electrode, a potential source for energizing said device, actuating means responsive to the flow of space current in said device, and means including a condenser for capacitively short circuiting said potential source to efiect response in said actuating means.

13. Electrical control apparatus comprising a space discharge device having an anode, a cathode, and an interposed control grid, a potential source for energizing said device, an actuating element shunted by capacity responsive to the flow of space current in said device, and means including a condenser for capacitively short cir cuiting said potential source to effect response of said element.

14. A remote control system operable from an electrical power supply line comprising, a space discharge device having a cathode and an anode connected respectively with opposite conductors of said line, means energizing said cathode, actuating means included in said anode connection responsive to interruptions in the iiow of space current in said device, and means for capacitively short circuiting said line at a remote point to effect response in said actuating means.

15. Remote control apparatus operable from an electrical power supply line comprising, a space discharge device having an anode and a cathode connected respectively with opposite conductors of said line, and an interposed grid, means energizing said cathode, actuating means interposed in said anode connection responsive to interruptions in the space current of said device, and means for capacitively short circuiting said line at a remote point to efiect response in said actuating means.

16. Remote control apparatus operable from a power supply line comprising, an electronic tube having an anode and a cathode connected respectively with opposite conductors of said line, and an interposed grid maintained free of electrical connection, means energizing said cathode, an actuating element shunted by capacity interposed in said anode connection, and means including a condenser for short circuiting said line at a remote point to effect response of said element.

17. Remote control apparatus operable from a power supply line comprising, a space discharge device having a control grid connected through series resistance and capacity, with each conductor of said line, a cathode connected with at least one said conductor, and an energized anode having in circuit therewith actuating means responsive to interruptions in the space current of said device, and meansfor capacitively short circuiting said line at a remote point to effect response in said actuating means.

18. Remote control apparatus operable from an electrical power supply 'line comprising, an electronic tube having an anode and a cathode connected respectively with opposite conductors of said line, and an interposed control grid, a normally actuated element shunted by capacity interposed in said anode connection, and means at a remote point for capacitively short circuiting said line intermittently at a rate effecting continuous deenergization of said element.

19. Protective control apparatus for an electrical power supply line comprising, an electronic tube having an anode and a cathode connected respectively with opposite conductors of said line, and circuit breaking means shunted by capacity included in said anode connection responsive to interruptions in the space current of said tube to open said line.

20. The method of utilizing an electrical power supply line while operating in its normal manner for remote control operation which comprises, establishing a localized flow of space discharge current between the conductors thereof

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