US310762A - weston - Google Patents

Description

(No Model.) 2'Sheets- Sheet l B. WESTON.

DYNAMO ELECTRIC MACHINE.

No. 310,762. Patented Jan. 13, 1885 (No Model.) 2 Sheets-Sheet 2.

B. WESTON.

DYNAMO BLEGTRIG MACHINE. No. 310,762. Patented Jan. 13, 1885.

TI I I l I I I I l l|||| I l I I I UNITED STATES PATENT OFFICE.

EDWARD IVESTON, OE NEIVARK, NEIV JERSEY, ASSIGNOR TO THE UNITED STATES ELECTRIC LIGHTING COMPANY, OF IIEIV YORK, N. Y.

DYNAMO-ELECTRlC MACi-ilNE.

SPECIFICATION forming part of Letters Patent No. 810,762, dated January 13, 1885.

(X model.)

To aZZ whom it may concern:

Be it known that I, ED'WARD WEs'roN, a subject of the Queenof Great Britain, and a resident of Newark, in the county of Essex and State of New Jersey, have invented certain new and useful Improvements in Systems of Generating and Utilizing Electricity, of which the following is a specification, reference being had to the drawings accompanying i0 and forming a part of the same.

My present invention relates to systems of electrical generation and distribution in which the devices for utilizing the current are con nected singly or in series in the circuit from one or more generators.

In describing my invention I shall consider chiefly those systems in which the working or translating devices are electric-arc lamps containing one or more electro-magnets and means for adjusting and feeding the carbon electrodes.

It will be understood, however, that the invention is applicable not only to such systems, but to others of an analogous kind, or, in other words, those which involve electrical devices operating and operated in substantially the same manner. In systems of this kind the resistance of the external or working circuit is subject to fluctuations or variations due mainly to two disturbing causes: first, the removal from or insertion in the circuit of one or more of the translating devices; second, the uneven action or operation of those devices in circuit. The ordinary operation of an arc lamp may be taken as an example of V thelast-named cause. In order that the lamps should offer an invariable resistance, it is necessary that the separation of the carbon points or the length of the arc should remain absolute] y the same, and that the quality and density of the carbons should be absolutely uniform. The accuracy of feed and adjustment which the first of these conditions implies is so far impracticable as to make it necessary to remedy rather than avoid the effects of 4 5 slight variations that are constantly occurring, and it is not possible in practice to obtain carbons of absolute uniformity. The strength of current developed .by a given generator depends, among other things, upon the magnetic intensity of the field, and with a dynamo ma- 5o chine the strength or intensity of the field is to a greater or less extent a function of the current flowing in the working-circuit. In I all systems of this kind in which dynamo machines are used a Variation in the resistance of the external circuit is attended by a variation in the strength of the current, and, assuming the running speed of the generator to remain constant, this implies a variation in the magnetic intensity of the field, which again reacts upon the strength of the current.

In order to avoid the more marked variations of current strength which would otherwise occur upon the bodily withdrawal or in sertion of one or more lamps, I make use of 6 a system of regulation the features of which it is not necessary to describe herein, as I have made the same subject of other applications for Letters Patent.

It is the object of my present invention to obviate the effects of the fluctuations of current due to the lesser variations of resistance, such as have been shown occur in the ordinary operation of arc lamps or similar devices; and my invention relates particularly to the type of dynamo machine known as the derivedeircuit or shuntwound dynamo,in which the field is excited by a shunt or derived circuit from the principal or working circuit. IVhen the field-coils are placed in the direct or working circuit, as is ordinarily the case in systems of this kind, such variations in the working resistance as are caused by the ordinary operation of arc lamps do not materially disturb the operation of the dynamo, and their reaction upon the intensity of the field is of such a character as to tend to correct any disturbance which may occur. If, for example, the are of anylamp becomes too long, the first effect is a reduction of current strength due to increased 0 resistance, and this diminishes the strength of the field of the dynamo and still further reduces the strength of the current, whereupon the lifting elcctro-magnet of the lamp being weakened allows the carbons to approach each 5 other and diminish the length of the are. In like manner any abnormal shortening of the are tends to correct itself with a dynamo having the field-coils in the direct circuit, and so long as no change is made in the number or adjustment of the lamps the system may be said to be in astate ofstable cquilibriu m. With. a dynamo, however, having the field-coils in derived circuit the reaction of such variations of resistance of the working-circuit upon the intensity of the fiel d appears to be very different and to tend to seriously interfere with the operation of the dynamo.

I have found that when it is attempted to run arc lamps with a shuntwound dynamo machine having its field-magnets constructed in the ordinary way, so that they respond readily to variations in the current exciting them, fluctuations are-liable to occur in the working-circuit, which seriously interfere with the working of the lamps and produce a state of oscillation in which the illuminatingpower of the lamps alternately increases and diminishes at frequently-recurring intervals. So far as I can ascertain, this appears to be due to the tendency of any reaction of the working-circuit upon the field to intensify the original disturbance of the working-circuit by which it is occasioned. Suppose, for instance, that the are of one of the lamps becomes slightly lengthened, although the increase of resistance in the working-circuit tends somewhat to reduce the strength of current, as in the direct-circuit dynamo, it also tends with the shunt-wound dynamo to increase the intensity of the field by diverting more current through the field-coils. and in this way to increase the strength of the current. This latter tendency is apt to be greater than the former, so that upon any slight increase of resistance in the workingcircuit the strength of the main circuit is increased, and, reacting upon the lifting electromagnets of the lamps, produces a still greater increase of resistance of the working-circuit, and this goes on until the limit of the capacity of the dynamo for developing electro-inotive force is reached, when, by a converse reaction, the current strength an d w orkin g resistance are diminish ed below the normal and another upward oscillation takes place. Such disturbances are also liable to occur from any momentary decrease of the working resistance, and the system is, so to speak, in a state of unstable equilibrium, in which any variation from the normal condition of the working-circuit tends to produce serious oscillations of current strength and resistance, such as would make the lamps too unsteady for practical use. This diflicnlty is not remedied by applying a current-regulator to the dynamo, since such regulators act only to correct disturbances, and not to prevent them, and it is diflicult, if not impracticable, to make a regulator respond as quickly as the lamps themselves. I have found, however, that the diihculty is entirely overcome by so constructing the field-magnets of the dynamo that they do not respond readily to variations in the current exciting them, butrequire more or lesstime for changing their intensity after a change has been made in the strength of the current flowing through the field-coils.

The variations of resistance in the workingcircuit incident to the ordinary operation of arc lamps to which I have referred are momentary or temporary in their character, since the feeding mechanism in the lamps tends to immediately restore the normal resistance of the arc whenever it is disturbed by any cause, and I make the field-magnets sufficiently sluggish in response to changes of current to allow such momentary disturbances to subside before any injurious reaction upon the intensity ofthe field takes place. This sluggishness or lack of sensitiveness ofthe field may be secured by increasing the mass of iron in the cores of the fieldmagnets, orby constructing them of hard iron, or in other ways which will readily suggest themselves to persons familiar with the construction of electro-magncts. The coils exciting the field should be composed ofa verylargc number of convolutions of comparatively fine wire, since the self-induction of the current in such a coil opposes rapid changes in its strength, and this is increased by increasing the number of convolutions. The degree of sluggishness to be produced for obtaining the result indicated will obviously vary somewhat with the size and construction of the machine and with the number and character of the lamps or other devices connected in circuit with it. W'ith the form of dynamo-machine and lamps employed in the are system devised by me, which is now in Common use, I have found that the result I have indicated is produced in an efficient manner by so constructing the field-magnets of the dynamo that an interval of from fifteen to twenty seconds is required for charging or discharging them that is to say, the field-magnets do not reach substantially their full intensity until fifteen or twenty seconds after the exciting-current has been applied in full force to the field-coils, and a like interval elapses after the field-cir cuit is opened before the magnetic intensity of the field is reduced to substantially its lowest point. It is not essential, however, for the purposes of my invention that this precise construction should be adopted. The field should, however, in all cases be made suiiicicntly sluggish to allow any momentary or temporary change of resistance in the working-circuit due to the ordinary operation of the arc lamps or other similar devices to subside or be corrected by the action of the devices themselves before any reaction upon the intensity of the field can occur, such as would increase or intensity the original variation in the lamp or other working device.

In carrying out my invention any suitable form of shunt-wound dynamo may be used, the iield-magnets of course being constructed in the manner indicated. I prefer, however, to construct the dynamo machine according to the general plan explained in my previous IIO orator.

patents, and especially Patents No. 209,532, dated October 29, 1878, No. 259,618, dated June 13, 1882, and No. 278,641, dated May 29, 1888-that is to say, I use a cylindrical armature composed of a number of sections or disks of iron strung on a shaft and recessed or grooved in line with its axis. The armaturecoils are wound longitudinally in the grooves so formed, and connected with the plates of a commutator, preferably according to the system of winding shown in my Patent No. 259,618. This armature is mounted between the pole-pieces of field-magnets which are wound witha large number of convolutions of insulated wire, forming a derived circuit from the main or working circuit, and so wound and connected as to produce consequent poles of unlike sign in the pole-pieces. The fieldmagnets are so arranged as to form the frame of the machine, and have attached to them proper supports for the bearings of the armature-shaft.

In the drawings hereto annexed I have shown, inFigurel, a machine with its field-mag nets partly in section, and in Fig. 2 a dynamo constructed in accordance with my invention, with an arbitrary number of lamps included in series with its armature-circuit.

A is the base of the machine. 0 is its cylindrical armature; B, the commutator, and D D the brushes from which the current is taken by the conductors E E. With the conductors E E are connected in series the translating devices, in this case are lamps F F, of which I have shown an arbitrary number ten. The lamps may be of any proper kind, though I prefer to use lamps constructed according to the general principles set forth in a patent granted to me September 25, 1883, No. 285,451.

G G designate the field-magnets of the gen I make them either of ordinary iron, using a very large mass, or of hard iron, or partly of soft and partly of hard iron, the latter being used for the interior of the cores, and the soft iron being applied or secured around it in the form of plates.

The precise construction of the cores necessary for producing the result I have indicated is readily determined by means well known to those skilled in the art, and varies according to the uses of the machine. The mass of the cores, the relative amounts of hard and soft iron, or thedegree of hardness of the iron used, and the number of convolutions of wire in the coils should be such in each case as to constitute a field so sluggish or slow in responding to variations of the current in the field-circuit that the irregularities in the op eration of the lamps giving rise to such variations shall have time to subside before any reaction upon the intensity of the field can be produced, such as would intensify or increase such irregularity and set up oscillations in the system.

a long length ofcomparatively fine wire around the cores of the field-magnets in such manner as to produce consequent poles of unlike sign in the pole-pieces K K. The ends of the fieldcircuit are connected to the binding-posts of the machine, so that the field-circuit is in derivation to the main circuit, and a Very large number of convolutions are wound on the cores of the lieldanagnets, so as to obtain the steadying effect of self-induction of the current as much as is practicable, and at the same time to allow suliicient current to pass to properly excite the field.

I have now described the best method with which I am acquainted for carrying my invention into effect; but I do not wish to be limited to the precise construction I have shown, since the construction ofthe machine or the lamps may be greatly varied and the useful result I have indicated still be obtained if the relations herein set forth between the field of the dynamo and the lamps or other devices be maintained. It is obvious, also, that when two or more machines are coupled together in series and run as one the results from their combined action will be the same as those secured by a single machine.

In describing my invention I have referred to are lamps as the devices for utilizing the current; but I do not wish to be limited to are lamps, as my invention may be used with advantage in connection with other devices operating in a similar waythat is, devices which in the operation of automatically regulating themselves incidentally produce temporary variations in the resistance of the working circuit. Electric motors, either used singly or coupled in series, and each provided with an automatic regulator for controlling their speed, would he an example of such devices. I have also spoken of the working devices as leing connected in series; but it is obvious that the advantages I have described would apply to the use of a single working device of the kind indicated with each generator. \Vhen two or more devices are used, they are connected in series.

I am aware that generators with field-magnets of great mass are not new, and also that hard iron and both hard and soft iron have been used in constructing the cores of such field-magnets. My invention does not consist in these features, however, but in the combination of a dynamo machine having its field coils in derived circuit and electrical translating devices placed in the main circuit,when constructed and arranged relatively to one an other in substantially the manner set forth.

W'hat I therefore claim is- 1. The combination of an electric circuit, translating devicesincluded either singly or in series therein, and a derived field-circuit dynamo machine having field-magnets of such degree of sluggishness relatively to the number and character of the translating devices that injurious reaction upon its magnetic in- 10 the lamps or other devices that variations in the action of such devices have time to subside before any reaction upon the magnetic intensity of the field takes place, such as would increase such variation, substantially as described.

In testimony whereof I have hereunto set my hand this 25th day of April, 1884.

ED \VARD XVESTON.

Witnesses:

HENRY A. BEOKMEYER, FRANK N. CRANE.

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