US546190A - Regulator for alternating-cu rrent dynamos - Google Patents

Description

(No Mom. 2 Sheets-Sheet 1..

E. W. RICE; Jr. REGULATOR FOR ALTERNATING CURRENT DYNAMOS. No. 546,190. Patented Sept. 10, 1895. 3191 E a v If g Q 7 T m 1 f 2 Ill/E111 Ur.-

mmwu g ANDREW B.GRAHAM. PHUTOLITNUWASIUN GTON. DC.

(No Model.) 1 2 Sheets-Sheet 2. .E. W. RICE, Jr. REGULATOR FOR ALTERNATING CURRENT DYNAMOS.

No. 546,190. Patented Sept. 10,1895.

Irg'rinr:

mam

Ming/2E5:

@wa/r i 9 ANDREW B.GRAIHAM. PHOTO-LH'NQWASHINGTON. [7.0.

UNrran States PATENT rates,

EDWIN \VILBUR RICE, JR, OF LYNN, MASSACHUSETTS, ASSIGNOR TO THE THOMSON-HOUSTON ELECTRIC COMPANY, OF CONNECTICUT.

- produced byavarying current flowing through REGULATOR FOR ALTEFlNA'T'lNG-CURRENT DYNAMOS.

SPECIFICATION forming part of Letters Patent No. 546,190, dated September 10,1895. i

I Application filed March 16, 1838. Serial No. 267,352. (No modeld To aZZ whom, it may concern.-

Be it known that I, EDWIN 'WILBUR RIoE, Jr., a citizen of the United States, and a resident of Lynn, in the county of Essex and State of Massachusetts, have invented a certain new and useful Alternating-Current Dynamo, of which the following is a specification.

My invention relates to alternating-current dyn'amos designed to preserve a constant difference of potential or a certain predetermined increase or diminution of potential, according as the conditions may require.

It consists, chiefly, in a novel means of varying the magnetic field, so as to increase or diminish its action on the armature in such manner as to compensate for the losses due to resistance and distortion of the lines of force the armature-conductors.

My invention consists in charging the fieldmagnet from two independent sources, one of which is a practically constant source and consists either of permanent magnetism, electricity from a separate dynamo, or of current from a coil upon the armature or armature-shaft of the altern atiug dynamo itself, while the other is a variable charging force and consists of the main-line current or a portion of the mainline current which passes to the alternatingcurrent main supplying the work, such current being at a point on the circuit locally commuted by means of a commutator to two opposite terminals of which the two terminals of a field-exciting coil are respectively connected. By this means the current forming the latter source is made to vary with the external work and can therefore be made to increase the power of the field-magnets exactly as the demands upon the machine increase. In connection with the commutator and the variable-current coil, both of which are placed in the main circuit leading to an alternating main, I employ a branch for said circuit around the coil, which branch includes a resistance having comparatively no self-induction and made preferably .variable,as will be more fully hereinafter described. By this means sparking at the commutator is prevented when a change of load occurs on the external circuit, as will be more fully hereinafter set forth.

My invention consists, further, in the particular combination of apparatus which will be more precisely stated in the claims.

The advantages of my invention are simplicity, certainty of action, freedom from sparking at the commutator, and automatic compensation for varying load.

It has heretofore been proposed to obtain automatic compensation for an alternating dynamo, but in the apparatus before employed the commutator which supplies the variable field-circuit has either been in the secondary circuit from a transformer or induction-coil or has been placed in a derived circuit from the work. These methods are more or less complicated and not so satisfactory, and are moreover liable to cause trouble by sparking at the commutator. In my invention the variable field-magnet coil is in direct circuit with the work supplied with alternating currents.

Referring to the drawings, Figure l is a perspective view of an alternating dynamo and separate exciter as combined in accordance with myinvention. Fig.2 is a diagrammatic view of the connections ofthe apparatus illustrated in Fig.1. Fig. 3 is a diagrammatic view of a modification of my invention, where the exciting-dynamo is dispensed with and the constant exciting-current is furnished by a conductor wound upon the armature of the alternating dynamo itself and commuted by a commutator. Fig. 4c shows in detail the method of winding the separate conductor used in furnishing the constant or initial current. Fig. 5 shows my invention applied to two dynamos in which the initial or constant current for exciting the fields is furnished by a separate dynamo and in which the variable field is produced by commuting the main current furnished by each dynamo.

Referring to Fig. 1, A indicates the armature of an alternating-current dynamo of any desired construction, the coils l, 2, 3, 4, &c., for the same being shown in the present instance as wound upon the exterior of such armature. The armature A may be constructed of anumber of thin iron plates carried by and secured to the shaft in any wellknown manner. F is the main field-winding, connected through the rhoostat R to the positive and negative brushes of the exciter E. F is the accessory field-winding, wound preferably as shown 011 each field-pole and on that portion of the pole-piece nearest the armature-conductors. One or two of the fieldmagnets may be wound with the variable field F, the remaining ones being supplied only with the constant current. The field-winding F has its two terminals connected respectively to two terminals of a commutator, the cylinder of which is indicated at K, while the brushes therefor are indicated at B B. The commutator-cylinder K is madeup, as usual in the art, of one or more pairs of com mutatonplates insulated from one another. The field-winding F is in the present instance shown as connected to the two terminals of the commutator, consisting of the brushes B B. The two other terminals of the commutator, consisting of the two sets of segments, are connected,as will be seen, respectively to one pole or terminal of the armature-coils and to the exterior circuitthrough the ring 0. The commutatorcylinder is fastened to the shaft and provided with a number of segments equal'to the number of alternations of current during a revolution of the armature. This commutator K may be constructed in any well-known manner, alternate segments being connected together so as to make practically a two-part commutator. In constructing and operating this commutator it is obviously only necessary that the changes of connection thereon should be timed to occur simultaneously with the alternations of the current supplied from the armature'coil to the main and the work. 0- O are two collecting-rings, upon which bear two brushes D D connected, respectively, to the terminals of the working circuit T T.

The electrical connections of the apparatus are more clearly shown in Fig. 2, in which similar parts are referred to by corresponding letters and numerals.

Fig. 2 shows diagrammatically the connections used in the alternating dynamo and the eXciter, Fig. 1. The field-winding F is furnished with a constant current from the ex citer E, which current flows from the brush 1) of the machine E through the resistance It, through the field-coils F, back to brush 1). The current from the exciting-dynamo E also divides through the brush Z), through the resistance R and its own field S to brush b. The current flowing through the field F can therefore be regulated either by varying the resistance R which varies the field S, thereby acting on the armature a, which generates the current flowing through the circuit between the terminals 1) b, or the current through F may be varied directly by varying the rheostat R. In cases where a single alternating dynamo is used the rheostat R would be dispensed with and the current flowing through the field F controlled entirely by means of the resistance B A, Fig. 2, indicates diagrammatically the armature-conductor, one terminal of which is connected to the segon the ring 0, and from D a wire is led to the external circuit containing the translating devices T T, &c., from which translating devices the current runs back to the brush 1), collecting-ring C, and from collecting-ring U to the armaturc-conduct r A, thus completing the circuit. The field F is connected between the terminals of the brushes 15 I3 which are bearing upon the commutator It. The effect of these connections'is, as will be seen, to put one terminal of the armature-coil A directly in circuit with one of the mains through the ring 0 and brush D, so that the alternations of current from said coil may pass directly to the main and to the work without being corrected. The circuit from the other terminal of the armature-coil to the opposite main is, briefly speaking, through the commutator and the field-exciting coil F to the other main, the coil being included in the commutator connections, so that the alternations of current will be locally commuted therein.

The resistance R with no or com 'iaratively little self-induction, is connected between brushes B B, thus forming a branch for the main current around the coil F.

The method of operation is as follows: When the armaturecondnctorA revolves within the influence of the field F, the current through which is constant in amount, being furnished by the exciter E, as just described, the electromotive force produced between the terminals of armature-conductor A has a certain fixed value. The amount can be altered by varying the current through F. No current flows through the field F or the commutator K or collecting-rings O C until the circuit is closed through the external devices T T, the; but when so closed the current flows through the armature A, one set of com mutator-blocks for the commutator-cylinder K, brush ll, coil F, brush B, to the otherset of com m utator-blocks or plates, collecting-ring 0, brush D, translating devices T, to brush D, collecting-ring 0, back to the armature-conductor A. The field-winding F, being in the comm utingconneetion between the terminals 13 B of the commutator, receives currents which are continuous or always of the same direction, but which on other portions of the main circuit alternate in the usual way. The amount of current thus tlowingin the continuousctnrent coil F is obviously dependent upon the amount demanded by the translating devices T T, (he. Acertain portion of the current is diverted by the resistance R for the purpose of regulating the field F. As ordinarily constructed an alternating dynamo would not have the commutator K nor auxiliary field F. In this case when the external translating devices T T were thrown into action the cur rent flowing in the armatureconductor A wo'ulddistort the lines of force passing into the armature, and the potential between the terminals of A would therefore fall in amount. It would also fall in consequence of the resistance offered by the armature-conductor A. It would then be necessary to increase the amount of current passing through the field F in any well-known manner-such as varying the resistance R R as is well known in the art. This, however, requires the manipulation of a resistance and constant attendance in order to prevent fluctuations in potential between the terminals of the translating devices in consequence of the varying amount of work demanded of the dynamo. By inserting the commutator K and commuting the main current and sending it through the auxiliary field F, I am enabled to increase the field automaticallyin exact proportion to the amount required to keep the potential up to the proper amount. By properly proportioning the number of turns of the field-wind ing F the fall of potential due to the causes mentioned abovei. e., the armature resistance and the distortion of the lines of force can be entirely compensated for-that is, the potential can be made to remain constant in amount upon throwing on the external translating devices. It is frequently found desirable in long circuits to save copper wire, a certain amount of loss being introduced between the dynamo and the translating devices T T. The fall of potential with a given res to make the necessary compensation.

sistance depends upon the current flowing through the circuit, and therefore in order to keep the potential constant at the translating devices T T it is necessary that the potential at the terminals ofthe dynamo should be increased. This can be accomplished by a proper proportioning of the field F. To facilitate this proportioning I have placed as a shunt about the field F the variable resistance R By varying the amount of the resistance R I am enabled to divert a portion of the main current from the field F, and thereby adjust it so as to produce any desired effect. In order to accomplish this the field F must be wound with Wire fine enough so that the field produced by it, in case the whole current is passed through it, is more than is desired In this case the resistance R is adjusted to divert just such proportion of the current as may be desired. 1 have also found that the resistance R has a new and even more valuable use than that referred to above. I find in practice that if the resistance R is omitted and the current in the external circuit is changed suddenly the commutator K sparks badly for a few moments and then gradually ceases sparking. This is objectionable, as it is liable to produce fluctuations in the lights or-other external work and burns the commutator and its brushes. The sparking is caused by the fact that the field-winding F has a large selfinduction and will not allow a sudden increase or diminution of current to occur in its winding, in consequence of which the current passes across the slots of the commutator K, causing the sparking mentioned, until such time as the field F has time to take up the line-current or to lose the current which is passing through it, when the sparking ceases until another change in the current takes place. By placing the resistance R which has little or no self-induction, in parallel arc with. the field-winding F, I am enabled to entirely obviate this sparking, the resistance R forming a path for the current in case it increases and also a path for the discharge of thecurrent in F when the main-linecurrent diminishes. This allows the main-line current to increase or diminish suddenly without affecting the commutator K. Of course it is understood that the resistance R takes up this-current only during the time in which the variation in current is taking place, and that as soon as the current ceases to vary the constant current flowing is divided between F and R in proportion to their actual resistance.

Referring to Fig. 3,in which similar letters and numerals refer to the same parts as in Figs. 1 and 2, and the same parts have similar functions, the constant field F, instead of being supplied by another dynamo or separate source of current, is supplied by a current generated in a conductor wound upon the armature of the alternating dynamo itself. This conductor a may be Wound over the surface of the armature, as shown in detail in Fig. 4, and instead of being wound in the form of a coil on the exterior of the armature, as are the coils 1, 2, 8, 4:, &c., it is wound transversely, as is shown clearly in Fig. 4. The armature-conductor 0, is carried out to a commutator N, which is constructed with as many segments as there are alternations during a revolution of the armature. The commutator N is the same in construction as the commutator K and commutes the alternatingcurrents produced in the armature-conductor a into a continuous current, which supplies the field-winding F. This armature-conductor, being independent of the armature-conductor A, furnishes a current very nearly constant in amount. Inpractice the current flowing through the armature conductor a, and therefore the field F, diminishes slightly with an increased current flowing through the main armature-conductor A. .It is therefore desirable in this case that the variable field F should be so proportioned as to increase slightly more in effect than it would in case the field F were furnished by an external source.v This proportion can readily be found by varying the resistance R until the potential between the terminals of the armature-conductor or collecting-rings C C re mains constant or increases in any predetermined ratio.

Fig. 4 shows in detail the method of winding main coils on armature-conductor A and the exciting-conductor a. Fig. 5 shows diagrammatically my invention applied to two dynarnos, in which the field-coils F F are sup plied by the same exciter E. The numerals and letters have the same significance as in the preceding figures. The external circuit T T T T can be separate circuits, as shown, or they can be connected in multiple arc in case the two dynamos are run together. In this case the resistance R R can be so adjusted as to give the proper initial field for the armature-conductors A A, and the resistance R can be so adjusted as to cause such an excitation of the field-coils F I as will give a uniform potential between the collecting-rings O O or an increase of potential, as may be predetermined upon, as described above. The Whole system may then be governed by the resistance R in the field of the exciter E.

What I claim as my invention is 1. The combination in an alternating current dynamo, of two field sustaining coils, one supplied from an armature coil connected directly therewith through a commutator, and the other forming a path for the main alternating currents passing to the work from an independent armature coil or coils, a commutator placed in the main circuit for locally commuting currents to said latter coil, a branch from the commutator terminals which are connected to said coil, and an artificial resistance in said branch.

2. In an alternating dynamo electric machine, the combination of a continuous current field exciting coil placed in the circuit to the alternating current work, and provided with a rectifying commutator for locally commuting the Work current in said coil, a variable resistance branch around said coil in a commuted portion of the circuit and of low self-induction, in combination with a field magnet coil through which a current flows of a strength independent of variations in the Work, as and for the purpose described.

3. The combination in an alternating current machine, of a field magnet produced by two independent sources, one practically constant and the other variable, of a branch having practically no se1f-induction around the coil forming the variable source, and means for Varying the resistance in said branch.

4. In an alternating current machine, the combination of a commutator, an armature coil one pole of which connects directly with the Work so as to supply alternating currents thereto while the otherpole connects with the opposite main through the commutator, and a field magnet coil in which the varying main line currents are locally straightened by means of said commutator, in combination with a variable resistance in a branch across the terminals of said field coil between the same and the commutator, and a field sustaining coil in which a practically constant current flows, as and for the purpose described.

5. In an alternating generator the combination with the field magnet coilandcommtr tator placed in the alternating current main, of a branch around said coil taken from a commuted portion of the circuit, and a field sustaining coil of practically constant elfect, as and for the purpose described.

6. In an alternating generator he combination with the field sustaining coil of practically constant effect, and a field magnet coil and commutator therefor placed in the alternating current main, of a variable resistance placed in a branch of the main around said coil and connected to the circuit at points between the coil and commutator, as and for the purpose described.

7. In an alternating generator, the combination with the field magnet coil and the pole changing commutator therefor placed in the alternating current main, of a branch of the main from the commutator around said coil, and a field sustaining coil of practically con stant effect, as and forthe purpose described.

8. In an alternating generator, the combination with a field sustaining coil of practically constant elfect and a field magnet coil and pole changing commutator therefor placed in the alternating current main, of a variable resistance in a branch of the main around said coil, as and for the purpose de scribed.

Signed at Lynn, in the county of Essex and State of Massachusetts, this 12th day of March, A. D. 1888.

' E. WILBUR RICE, JR. \Vitnesses:

J. W. Grnnonnr, GEO. F. CURTISS.

Images