US429333A - Process of maintaining a uniform current in electric circuits - Google Patents

Description

(N0 M0del.) 4 Sheets-Sheet 1. J. M. BRADFORD. PRCCESSCI' MAINTAINING A UNIFORM CURRENT IN ELECTRIC CIRCUITS.

No. 429,333. PatentedJune 3,1890.

R 0 T N E V N W ITN ES SE82 QM'WW. NMM.,

(No Model) 4 Sheets-Sheet 2.

J. M. BRADFORD. PROCESS OF MAINTAINING A UNIFORM CURRENT IN ELECTRIC CIRCUITS.

Patented June 3,1890

WITNESSES: INVEN OR:

5 W\.\3va.-MW

4 Sheets-Sheet 3x (No Model.)

J. M. BRADFORD. v PROCESS OF MAINTAINING A UNIFORM CURRENT IN ELECTRIC CIRCUITS.

Patented June 3, 1890.

WITNESSES (No Model.) 4 Sheets-Sheet 4.

, J. M. BRADFORD. PROCESS OF MAINTAINING A UNIFORM CURRENT. IN ELECTRIC GIRGUIT'S.

No. 429,333. Patented June 3, 1890.

q o o WITNESSES: INVENTOB'.

UNITED STATES PATENT OFFICE.

JULIEN M. BRADFORD, OF PORTLAND, MAINE.

PROCESS OF MAINTAINING A UNIFORM CURRENT IN IZLECTRIC CIRCUITS.

SPECIFICATION forming part of Letters Patent No. 429,333, dated June 3, 1890.

' Application filed September 22, 1888. Serial No. 286,125, (No model.)

To all whom it may concern.-

Be it known that I, JULIEN M. BRADFORD, a citizen of the United States, residing at Portland, in the county of Cumberland and State of Maine, have invented new and useful Improvements in Processes of Maintaining Uniform Current in Electric-Lighting Circuits, of which the following is a specification.

My invention relates to systems of electrical distribution; and the purpose thereof is to provide automatic means whereby the current strength upon circuits may be regulated and maintained at a certain degree or at a substantially uniform intensity.

The methods described in the following specification are widely applicable to different systems of generating and distributing direct and alternating currents, being especially intended to control the current on incandescent and arc light circuits, for the purpose of preventing dangerous electrical pressure, securing uniformity of light, and other advantages incident to proper regulation.

Automatic methods for the above purpose, heretofore described, are characterized by one or more of the following features: inability to move the regulating mechanism with quickness and precision on the commencement of a slight variation of the current to be regulated and to control. or cut off said movement with accuracy when sufliciently expended; second, inability to maintain the regulating mechanism in a given position unassisted by the force of the current to be regulated. It results, therefore, that automatic regulators based upon said methods act very slowly if sensitive to slight changes in the current to be regulated and capable of moving the regulating mechanism with precision through con siderable distances.

In the following specification will be described methods diti'ering radically from the foregoing, inasmuch as regulating action even of great energy can be produced by the slightest change in the current to be regulated, and this action can be controlled with as great accuracy as that formerly obtained from slowworking'methods. Therefore by such amethod material changes in mainline currents can be anticipated or prevented, instead of being reduced after they are developed.

Prominent among the purposes for which this invention provides a method, one or more of which may be used in practice, are the following, described in six paragraphs, as follows:

First, a method whereby a rheostat or other the operation being such that the action obtained thereby may be the sum or the difference of the action of two or more of said rheostats or factors acting at the same time.

lhird, a method whereby progressive regulating action may be obtained, as before stated, for the purpose of actuating a rheostat or other regulating factor controlling a circuit, and of holding stationary said rheostat or factor unaided by the force of the current on said circuit.

Fourth, a method of operating regulating apparatus progressively, as before stated, and with a minimunrexpenditure of motive power to adapt the apparatus for use in places remote from the dynamo-station, I

Fifth, a method whereby a current-indicator of such construction is used that regulating apparatus is actuated by successively closing local circuits, thereby preventing oxidation of the contact-points and assuring other advantages explained in the fifth section of the following specification.

Sixth, methods of controlling the generative capacity of dynamo-electric machines; also, other methods of arranging compensating circuits and of maintaining the com pensation when secured.

\Vhile my invention may be carried out by any of the several systems and modes of operation hereinbefore referred to, I do not herein claim said systems specifically, restricting myself in this application to claims for the general mode of operation, and the several systems are described simply to show that the method may be carried into effect in various ways.

Of the drawings illustrating this invention, Figure 1 is a front view of a regulator with a current-indicator in electrical connection therewith. Fig. 2 is a front view of a regulating device and also wheel 16. Fig. 3 is an end view of Fig. 1. Fig. 1 is a front view showing a diiferent mode of arranging magnets 15. Fig. 5 is a diagram showing the construction of a rheostat that may be operated by a regulator. Fig. 6 is a front view of a regulator in electrical connection with a current-indicator. Fig. 7 is a front View of two eccentrics arranged for accumulative and differential action. Fig. 8 is a plan of an arrangement for concentrating regulating action. Fig. 9 is a diagram illustrating a method of operating regulating apparatus with economy of motive power. Fig. 10 is a detail of 11. Fig. 11 is a frontview of a current-indicator. Figs. 12, 13, 11, and 15 are diagrams illustrating applications of the regulating apparatus described in this specification.

In describing this invention and also modes of applying it to practice the following specification will be divided into six sections, as follows:

First. Regulator A, Fig. 1, should be placed in any suitable place relatively to the work to be performed. The pulley 5 may be bolted to any suitable source of power, such as the power-shaft driving a dynamo. To pulley 5 is fixed shaft 2, which carries eccentrics 6, fixed on said shaft at an angle one to the other, as shown in Fig. 7. The eccentrics 6 operate regulating devices, one of which is shown in Fig. 2. This device consists of a T-shaped lever 28, with open frame at 29, pawls 30, springs 31, and electro-magnets 15. The levers 28 are pivoted on shaft 1, which has regulating-wheels 16 fixed to it. The regulating-wheels have teeth, and a gap or space may be uncovered by teeth, if desired, as a means of limiting the movement of said wheels. Shaft 1 may move a rheostat of the construction shown in Fig. 5 as a means of regulating a circuit, or said shaft may move the com imitator-brushes of a dynamo-electric machine as a means for that purpose, several modes of applying the regulator being illustrated by Figs. 12, 113, 11, and 15, and explained in the sixth section of this specification. \Vhen the rheostat is used as a means of regulating a current, it passes through the arrangement by way of the binding- posts 17 and 21, and consequently is of maximum force when the contact-arm 18 is at the extreme right, of minimum force when the arm is at the extreme left, and of intermediate force when the arm is in an intermediate position. The pawls 30 are drawn away from the wheels 16 by springs 31; but should a magnet 15 be energized a pawl 30 is drawn into engagement with a wheel 16 and causes it to move. Any suitable current-indicator may be electrically connected with this regulator, those capable of noting a gradual change in current by a gradually-increasing deflection being preferred. In the current-indicator C the helix. 1 3 receives through wires a fraction of the current from the circuit to be regulated, thereby causing lever 12 to be moved or deflected more or less, according to changes of current in said circuit. Above lever 1'3 is a binding-post 35, which derives a local current of suitable strength from a dynamo or other source and communicates it to lever 12 by the wire connected thereto. The bindingpost 36, representing the other pole of the local circuit, is in electrical connection with magnets 15 of the regulator. The indicator lever 12 is so adjusted that it will not touch either of the screws 15 or 16, while the current to be regulated is of the right degree of strength; but should that current increase screw 15 is touched, completing a local circuit and energizing the left-hand magnet 15, which causes a pawl to engage with a wheel 16 and move shaft 1 to theleft, thereby red ucing the current, as subsequently explained in the sixth section of this specification. The instant the current which is being regulated is reduced to a normal degree of strength the lever 12 drops from the screw 15, causing the local circuit to be broken and thereby causing magnet 15 to release pawl 30, which is instantaneously drawn away from the teeth of a wheel 16 by a spring 31. This causes the shaft 1 to stop on the instant of the disengagement of pawl 80 by reason of the friction of arm 18, which bears with slight pressure upon the contaet-plates of the rheostat. The contact-spring 19 also bears with slight friction upon arm 18, in order to maintain an electrical connection between them. The shaft 1 now remains at rest until the current to be regulated declines below the normal degree, when screw 16 is touched, causing a local circuit to be completed through the right-hand magnet 15, thereby causing a pawl 30 to move the shaft 1 to the right and increase the current.

The regulator shown in Fig. 1 contains two regulating devices of the construction shown in Fig. 2; but three or more of said devices can with advantage be arranged to work upon shaft 1, especially if it is desired to increase quickness of action. Each regulating device should be operated bya separate eccentric 6, arranged at an angle one to the other on shaft 2. Increased quickness of action of such an arrangement results from the unequal circumferential velocity of the eccentric-disks 6. Such beingthe case, each during its moment of maximum movement will lead in moving wheels 16 and shaft 1. 'lhereforcincreased regulating action can be obtained by the arrangement without increasing the rate of motion of the driving-pulley 5. Instead of arranging a separate regulatirig-wheel 16 to receive the action of each regulating device, as shown in Fig. 3, each wheel 16 may receive the action of two regulating devices by placing the wheel between them, the pawls 30 being suitably arranged to engage with the wheel. Each magnet 15 is also capable of actuating several pawls, so that the number of magnets is not necessarilyincreased when more regulating devices are added.

The regulator last described differs from 4 others usedin the art by its capacity for rapid progressive action combined with precision of regulation, which commences on the inception of the slightest change in the regulated current that can be detected by the currentindicator. This action is under control. Its quickness is determined by the rate of motion of pulley 5 by the number of eccentrics and their angular arrangement, also by their diameter or throw, and said act-ion, when sufficiently expended, is instantaneously cut off. Pawls 30 are required to move but a slight distance to make engagement with a wheel 16. Therefore a com paratively weak current from the dynamo will sufliciently energize magnet 15 to cause a pawl to be thrown into engagement. The pawls also bear against the teethof the wheels 16. Therefore the movement of said wheels is positive without slipping. Springs 31 apply sufficient tension near the pivot of pawls 30, so that said pawls instan tan eously spring from wheels 16 on the breaking of a local circuit. With such provisions there is hardly a possibility of the pawls acting at the same time on opposite sides of a wheel 1.6, and thereby straining or breaking some part of the regulator. Still if it is desired to provide for such a contingency, an arrangement for that purpose is shown in Fig. 8 and described in the latter partot the second section of this specification.

The pawls of the regulator shown in Figs. 1 and 3 act with greater effect and precision than pawl mechanism with the ordinary forward and return stroke. \Vhen pawls are operated in the latter manner, one-half of the time is lost in making the return-strokes, which cause no movement of the wheel which is being propelled. Therefore the action is intermittent instead of being continuous. Little is gained byincreasin g the speed of the pawls, for at any rate of speed one-half of the strokes are ineffective, and excessive speed causes vibration and irregularity of action. It therefore results that ordinary pawl mechanism is incapable of either instantaneous or continuous action. By operating pawls by eccentrics arranged on the driving-shaft at an angle, one to the other, a new result is obtained. The pawls move in both directions at the same time, the arrangement being thereby capacitated for instantaneous, continuous, and accurate action in either direction. The

eccentrics may be said to be arranged for accumulative and differential action, because by this means action maybe accumulated in the same direction 'or be applied first in one the pawl. Stationary magnets, however, have the advantage of each operating a considerable number of pawls, as has been before explained.

Second. The regulator shown in Fig. 6 differs from that shown in Fig. ],in having two separate shafts 4:, which, with the rheostats attached, are moved independently of each other by the regulating devices. The current to be regulated passes through both rheostats by way of the binding- posts 17 and 21. The double rheostat, operated by two regulating devices and two eccentrics, changes the current passing through it with the same quickness as a single rheostat operated by two regulating devices, (shown in Fig. 1;) but by increasing the number of regulating devices and eccentrics for operating the inde pendent shafts 4, or by separately operating three or more rheostats in a series, the arrangement becomes capable of an in crease of action resulting from the combined effect of two or more contact-arms 18, moving in the same direction at the same time, or the difference of action of two or more of said arms moving at once in opposite directions. Each regulating device in the above regulator is the same as that shown in Fig. 2. In practice it probably will be preferred to use springs 31 of suilicient tension to cause a pawl 30 to disengage from a wheel I 16 on the instant of breaking a local circuit. If this tension is insutlicient to cause the pawls to disengage while they are in operative contact with wheels 16, the stroke will continue for its entire length, but will be prevented from seriously disturbing the current which is being regulated by the neutralizing effectof the other arm 18, which is caused to move in the opposite direction on the instant said current is slightly overcompensated and the current-indicator c deflected thereby in the opposite direction. Fig. 8 shows another way of concentrating action upon one shaft as for the purpose of moving the commutatorbrushes of a dynamo-electric machine. The arrangement consists of a shaft 4, having a gear D meshing with gears 48 on actuatingshafts 46 011 opposite sides of gear D. The

shafts 4:9 carry the regulating wheels 16, which IIO the regulating; devices act oppositely at the same time the pinious l8 slip on their shafts without imparting motion to the gear D. But, as before explained, springs 31 maybe of sufficient tension to cause pawls 30 to disengage from wheels 10 on the instant of breaking a local circuit, thereby preventing opposite ac tion at the same time. The springs 47 cause suflicicnt friction to overcome any slight momentu 111 of wheels 16. Therefore shaft l stops on the instant that the regulating devices cease to move it.

Third. By all the foregoing arrangements the regulating-wheels 16 move with slight f riction, thereby causing the regulating mechanism attached thereto to remain in any position to which it may be moved. An incipient variation of the current which is being regulated is sufficient to cause the motive power to move contact-arm 1 8 or other regulating mechanism, and this mechanism is held by friction in the position to which it is moved. Therefore a variation of force of the current which is being regulated plays a secondary part in securin g a compensation of said current and no part in maintaining this compensation when secured. If a great number of lamps are arranged in multiple are 011 a main line, it is evident that the current in amperes fed to the line should be small when but few lamps are lighted, and that said current must be greatly increased when all the lamps are in use, although the electro-iuotive force of the line-current should at all times remain unchanged. On the other hand, if a certain number of lamps are arranged in series, the current required is the same for a small as for a great number of lamps; but the electro-motive force must be increased if the number of lamps is increased and decreased when the lamps are switched out of circuit in the usual way, the regulation of the electro-motive force being for the purpose of n'lainta-iniug a suitable electrical pressure to cause a current of a required nu mber of amperes to flow through the circuit. Besides the changes of resistance on the circuit, for which compensation must be made, there are irregularities of the generative ca pacity of the dynamo from change in engine speed. It results, therefore, that it is often required to largely increase the current fed to a cireuit,whilc the electro-motive force remains practically constant, and in other cases to increase the eleetro-motive force and maintain a constant current.

The regulators described in this specification are adapted to transiently move the regulating mechanism for the purpose of preventing transient irregularities of current, and also to sustain new adjustments of said mechanism unaided by the force of the current which is being controlled. Therefore circuits may be regulated for constant potential or for constant current.

Fourth. If it is desired to use the regulat in g apparatus in places other than at the dy namo-station, said apparatus may in such instances be worked by a special motor, as ordinarily there will be no engine at work in such places from which motive power can be derived. It will also be well to cause the motor to remain at rest, excepting while the regulating apparatus is being moved, as by this means power will be econom ized tothe greatest extent. An arrangement for the above purpose is shown at Fig. 9, in which the elect-ricmotor J is attached to pulley 5. A part of the current from the circuit to be regulated flows through wires 25 to helix a3. It the current to be regulated increases beyond the required degree, the indicator-lever 42 touches screw 45, causing a local current to flow from binding-post to screw 45, thence through the left-hand wire 3 to the left-hand magnets 15, thence through the coils of motor J, and back to the other pole of the local circuit at 36. The motor J starts the regulator by moving pulley 5, magnets 15 at the left are energized, and a compensation is made in the current to be regulated, as before described. As soon as the compensation is completed the indicator-lever l2 drops from screw 45, thereby breaking the local circuit and stopping motor J. If the current to be regulated declines below the right degree of i11- tensity, screw it) is touched, causing the motor to start, the right-hand magnets 15 to be energized, the current to be regulated, and the motor to again stop, when the indicator lever it breaks the circuit through the righthand wire 3. It is probable, unless motor I is of small power, requiring but a weak current to operate it, that the contact-screws l5 and a0 would soon become oxidized by sparks escaping at the moment of breaking the local circuits by lever l2. The liability to this dofeet and the necessity of frequently scraping and read justing the lever l2 and contactscrews to insure the operation of the apparatus can be wholly avoided by causing lever 42 to successively close local circuits and thereby operate the apparatus, said method being fully explained in the next section of this specification. It is evident thatother motors-such as those worked by compressed air, water, or by a weight-can be substituted for the electric motor, as will also be nextexplained.

Fifth. A cu rrent-imlicator may successively close local circuits and thereby actuate regulatiug apparatus. Fig. 11 shows an instrument of the above kind,which utilizes a slight power during its moments of action, to supply which pulleys 59, having friction-washers 60 attached to them, may be loosely supported upon shaft-s 62 and be belted to the powershaft of the dynamo; but where a power-shaft is inaccessible two winding-drums, to which weights are attached, Fig. 10, may take the place of pulleys 59 and frictionavashers (it). The friction-washers 60 are attached to pulleys 59 and press with sufticient force upon gears 50 to cause a wheel 1 to move when an armature-lever it is lifted, thereby allowing a fly t to pass. A fraction of the current from the circuitto be regulated flows through wires 25 to wire or other suitable conductor, thereby slightly heating it in proportion to the quantity of current. The needle 42, screws 53 and 57, contact-springs 55, :r, 00 m, and m are insulated from the metallic bed-plate, upon which they are supported. The needle 42 is adjusted relatively to pin f and screws 53 and 57 in such a manner that while the circuit to be regulated is carrying a current of normal strength needle 42 does not touch either screw 53 or 57, but rests upon pin f. If that current increases, wire 50 expands, causing needle 42 to touch screw 53. If the current declines, wire 50 contracts and screw 57 istouched. This current-indicator may be substituted for indicator 0 of Figs. 1, 6, and 9, the wires 3 and 9 of Fig. 11 being for the purpose of conveying currents to magnets 15 of the regulating devices before described.

The operation is as follows: Ifscrew 53 is touched by needle 42, a current flows from battery 52 to needle 42, thence to screw 53,

thence through the left-hand magnet 54,

thence through spring to pins, and thence to the other pole of the battery 52, which is connected to the metallic bed-plate of the indicator. The left-hand magnet 54, being energized by the current, lifts the left-hand armature-lever 17, allowing the fly t to pass. Immediately after fly t escapes from lever a pin 3 slips off of spring 55 by reason of the movement of Wheel P, thereby breaking the circuit of battery 52, causing lever 91 to regain its former position and stop fly t after it has made one-half of a revolution. The movement of wheel P causes a pin 8 on that wheel to touch spring m, thereby allowing a current to flow from binding-post 35 to the bed-plate of the indicator, thence through the bed-plate to pin .9, and thence by spring m and wire 3 to magnets 15 of the regulating devices before described. When needle 42 returns to pin f, a current flows from battery 52 to magnet y, thence to spring at, thence to pin 3, which touches said spring from the former movement of wheel P, and thence through the bed-plate of the indicator to the other pole of battery 52. Magnet 3 being momentarily energized by the current, causes fly t to escape, and wheel P to make one-fourth of arevolution and stop, as before. The circuit through spring m is broken by this movement of wheel P. If needle 42 touches screw 57, the right-hand magnet 54 is momentarily energized by a current from battery 52, as before described, thereby causing wheel P to make one-fourth of a revolution, pin 3 to touch spring m and a current to flow through the right-hand wire 3 to the regulating devices. hen needle 42 returns again to pin f, magnet y is momentarily energized,as before described,by acurrent from battery 52, and wheel P makes one-fourth of a revolution and stops, as before. The circuit through spring m is broken by this movement of wheel P. The

advantages of the above-described method are that oxidation is prevented at the contact-points of needle 42, that instruments of fine adjustments can be used, and that the .eifect of a jar that would otherwise cause such an instrument to close and break'the local circuit a great many times in quick'succession when needle 42 is very near the point of contact is prevented by the circuit being instantly broken by wheel P after the first contact of needle The friction of pins 3, rubbing against springs m and m is suiii cient to insure electrical contact. Therefore a stronger current from the dynamo or other suitable source can be broken and closed by said means than could be broken and closed by an instrument of line adjustment operating without friction of its contact-poi nts.

One of the uses of the above method is to operate a combined motor and regulator with economy of power, as described in the fourth section of this specification. It is evident that needle 42 can be magnetically deflected, as in indicator C, before shown, instead of causing deflection by theexpansion and contraction of wire 50.

If a motor worked by water or compressed air be substituted for electric motor J of Fig. 9, the pins 5 on wheels P, Fig. 11, may engage with the valves controlling the fluid working such motors, thereby opening and closing said valves and operating the motor intermittently for the purpose before de scribed.

Sixth. Figs. 12 and 13 show methods of controlling the generative capacity of dynamoelectric machines in accordance with the requirements of circuits.

Fig. 12 represents a dynamo S5 feeding lamps arranged in series. The commutatorbrushes of the dynamo may be attached to shaft 4 of the regulator A in such manner that said brushes are both equally moved by shaft 4 to and from the position for maximum current. If there are transient irregularities of speed of the engine driving the dynamo, the brushes are transiently moved to prevent the effect of such irregularities. If one or more lamps are switched out of circuit, the regulator automatically makes a new adjustment of the brushes, thereby reducing the generative capacity of the dynamo, and consequently the pressure of the current on the lamp-circuit. This adjustment may also be maintained unaided by the force of the current, as explained in the third section of this specification. If one or more lamps are added to the circuit, the brushes are moved and adjusted in the opposite direction, increasing the generative capacity of the dynamo, also the pressure 'on the lamp-circuit. The new adjustment may be maintained, as before stated. By such means the generative capacity of the dynamo is caused to accord with the requirements of the circuit which it feeds.

Fig. 13 represents a shunt-wound dynamo 86 feeding a circuit with incandescent lamps arranged in multiple arc. The current which is shunted around the field-magnetol' the dynamo passes through the rhcostat of the regulator at A, and by this means the magnetic field is increased or decreased or maintained at a certain degree of strength, thereby causing the output of the dynamo to accord with the requirements of the circuit which it feeds.

Figs. ll and 15 illustrate another method of preventing wide variances of currentstrength. In Fig. ll: the small dynamo 92 excites the field of dynamo 93, which feeds con verter [it at a distance from the dynamo with an alternating current. Both of the dynamos are regulated, as shown by the drawings, according to the pressure of the current-feeding converter 91. The converter 9i feeds two lamp-circuits. Regulators A operate each a rhcostat, one being included in each lampcircuit to prevent either of said circuits from receiving too much or too little current when the resistance is changed by altering the number of lamps on a circuit.

Storage batteries or converters may be fed with a high-pressure current from a distant dynamo and act at sub-stations from which low-pressure currents for lamps are distributed.

Fig. 15 illustrates another mode of dividing a high-pressure current from dynamo 95 into two or more lamp-circuits. The two lamp-circuits at the right of the figure are separately regulated or compensated by the rheostats of regulators A to prevent variances of current in either lamp-circuit.

In the above, Figs. 12, 13, 14, and 15, each cnmrent-indicator C is electrically connected by wires with the circuit to be regulated, and also by wires 3 and 9 to a regulator A, which controls the circuit, all of which has been explained in detail in the first part of this specification.

lVhat I claim is 1. The method of rapidly compensating ineipient variations of current in a generatoreireuit, which consists in causing two or more regulating devices or other compensating agents to act aecuniulativcly each with a progressively-increasing eii'ect the instant the current varies either byincrease or decrease.

The method of rapidly counteracting incipient variations of current in a generatorcircnit, which consists in causing two or more regulating devices or other compensating agents to actaceumulatively or differentially each with a progrcssively-increasing effect the instant current varies either by increase or decrease, thereby preserving uniformity of current.

The method of rapidly counteracting incipient variations of current in a generatorcircuit, which consists in causing a compensating resistance or current-varying device to act progressively, and neutralizing the effect of an excess of progressive action by causing said compensating device to act ditferentially by retrogressive action the instant the compensation overshoots the required limit.

JULIICN M. BRADFORD.

Witnesses:

II. M. BRADFORD, ALBERT C. NEAL.

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