US712451A - Exciting-dynamo. - Google Patents

Description

no; 7|2,45|. Patented on. 28, 1902.

u. w. BUCK.

EXCITING DYNAIO.

(Application 810d In. 31, 1902,) (In llodek) 2 Sho ets-Sl\eet l.

WiTHESSESI 1 1/ I 4 HaroHWBugk.

No. 7l2,45|. Patented Oct 28, I902.

- "WW. BUCK.

Excmue DYNAIO.

A limion filed In. 31, 1003.

(No Model.) 2 Sheets-Shut 2.

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UNITED STATES PATENT OFFICE.

HAROLD W. BUCK, OF NIAGARA FALLS, NEW YORK, ASSIGNOR TO GENERAL ELECTRIC COMPANY, A CORPORATION OF NEW YORK.

EXCITING-DYNAMO.

SPECIFICATION forming part of Letters Patent No. 712,451, dated October 28, 1902.

Original application filed September 2,1898, Serial No. 690,133. Divided and this application filed March 31, 1902. Serial No. 100,652. (No model.)

To all whom it may concern:

Be it known that I, HAROLD W. BUCK, a citizen of the United States, residing at Niagara Falls, county of Niagara, State of New York, have invented certain new and useful Improvements in Exciting-Dynamos, (Case No. 2,809, a division of my prior application, Serial No. 690,133, filed September 2, 1898,) of which the following is a specification.

My invention relates to a method of exciting the fields of direct-current dynamo-electric machines and may be embodied in a construction in which the usual field -magnet winding is entirely omitted and in which the I 5 excitation is due to artificially-produced leadingcurrents in the coils of the armature or' other winding movable relatively to the fieldmagnet.

In the drawings attached to this specificazo tion, Figures 1 to 5, inclusive, are illustrative diagrams. Fig. 6 represents diagrammatically an embodiment of my invention; and Fig. 7 a modification of the same.

Before proceeding to a description of my 2 5 invention a few well-known principles will be reviewed in order to make clearer the explanation to follow.

In Fig 1 let G represent a Gramme ring of the usual form, and M an internal field-magnet energized from some external source of direct current. Let the armature be tapped at diametrically opposite points a b, so as to form an alternating-current generator, and assume the armature to be rotated in the direc- 3 5 tion of the arrow, the current generated being fed to a non-inductive load R. With this arrangement the current will be approximately in phase with the impressed electromotive force, so that the maximum armature-current will flow at the same time that the armature electromotive force is a maximum. The relative position of armature and field corresponding to maximum armature electromotive force is shown in Fig. 1, in which the diameter a b is at right angles to the field. In this position the armature and the field magneto-motive forces are at right angles to each other, so that there is nocomponent of either magneto-motive force in the direction of the other.

tion of the armature.

The armature-current will therefore neither magnetize nor demagnetize the field by its. reaction thereon. The only effect is one of distortion. Suppose, however, that the generator feeds a load having capacity reactance, such as a condenser K, Fig. 2. In this case the current will not be in phase with the electromotive force producing it, but will lead by an angle equal approximately to ninety degrees or one-quarter of a period. In this case, therefore, the armature-current will reach its maximum onequarter of a period earlier than if the load were non-reactive, as in Fig. 1, and the armature-terminals a b will consequently occupy a position displaced or trailed backward ninety degrees when the maximum value of current occurs, as illustrated in Fig. 2. By making the armature -current leading it reaches its maximum earlier, and its magnetomotive force has a component in the same direction as the field-exciting magneto-motive force, and so assists the latter. 'As the armature rotates to the position shown in Fig. 3 the armature-current becomes zero, at which time there is no magnetizing reaction on the field. One-quarter of a revolution later, as shown in Fig. 4, the condensercurrent again becomes a maximum and the field is reacted upon and magnetized in the same direction as in Fig. 2. Twice every revolution, therefore, the field will be magnetized by the reaction of the leading armature-current, thus producing a pulsating flux of a frequency depending on the rate of rota- If, however, as shown in Fig. 5, the condensers be connected at regular intervals about the armature-winding, so as to be in multiphase relation thereto, there will be a practically constant reactive magnetization of the field by the leading condenser-currents in the armature. The ex-. ternal magnetization of the field may consequently be removed, and the system will excite itself by the reaction of the wattless. leading-currents in the armature.

Having thus reviewed the principles underlying my invention, I will now proceed to a description of the same as embodied in a direct-current dynamo-electric machine.

I chines.

In Fig. 6 G is a suitable armature, here shown as a Gramme ring. At equal spaces about the armature connections are tapped off to a corresponding number of sources of leading electromotive force 0 C C. These may be either condensers, electrolytic cells, or overexcited synchronous motors. Acornmutator K is connected to the armature in the usual way, with brushes B B bearing thereon. An unwound field-magnet V is in inductive relation to the armature and is here shown as internally arranged with respect to the same. As has been seen, the reaction of the leading-currents flowing in the condensers' will magnetize the field, and the field thus established will generate a direct current which may be taken from the commutator by the brushes B B, as in other direct-current machines. The leading-cu rrents will continue mutator.

The mechanical construction of a machine such as described may undergo many modifications and its principle may "beembodied in manydiiferent typesof machines without departing from the spirit of my invention.

Thus the field-magnets maybe either internal, as shown in Fig. 6, and without windings thereon, or they may be external, with short projections forming the pole-pieces.

In the latter case the poles are short and the magnetic circuits com pact, because no necessity exists for providing space for winding I.

field-coils.

In Fig. 7 of the drawings I have-showndiagrammatically an arrangement of apparatus similartothatshown in Fig. 6, but'comprisin g in addition means whereby the capacity or condenser effect may be conveniently varied,and thereby vary the di-rect-currentelectromotive force. Referring to Fig. 7, V represents an unwound field-magnet either sta- In inductive j relation thereto .is a relatively rotatable armai tnre .G, having any suitable winding, which in the instance shown is of the Gramme type. This winding is tapped at intervals andfconnected to the segments of a commutator K in a manner common to direct-current ma-l Brushes B B bearon thecommutator and serve to collectand transmit thecurrent generated to the external circuit. Thear-ma- 1 ture-winding is tapped at suitable intervals i and connections led ofi through collector- 5 rings or by other appropriate means to the Inthe case shown tionary or capable of rotation.

primary of a transformer.

in the drawings the armature-winding is tapped at three equidistant points, so as to produce .electromotive forces displaced in, phase from each other by one hundred and twenty degrees. The transformerrequired is therefore oflthe three-phase type. Although in the form shown the transformer windings, both primary and secondary, have a Y connection, it is obvious that the delta connection may be employed in either primary or secondary,or -both,as may bedesired. Acondenser G is connected to the secondary of this transformer and is of the three-phase type, in which three sets of plates are connected, respectively, to the three-phase mains, while the remaining sets of plates are connected to a common point, or what amounts to the same thing, in parallel. This condenser is connected withthesecondary of the transformer by conductors connecting, respectively, with the switch-arms 7, 8, and 9, as shown. Each switch-arm cooperates with a plurality of contacts 11 in electrical connection with points in the winding ofeach leg'of thetransformer. By-shifti-ng the switch-arms from 'one set of contact-points to another the ratioof transformation of the transformer, and .consequently its secondary voltage, is changed. By so-doing the capacity effiectinthe primary due to the condenser in the secondar-y is varied in a manner well understood by engineers, thereby varyingthe-volu-meof leadingcurrents in the windingof the armature G. The field excitation-variesinaccordance with the variation of leading-currents, and thus regulates and determines the desired current and voltage of the machine. The switcharms 7, 8, and 9 may be operated independently, if desired; but I find it more convenient to connect them together by a connecting-rod 10, so as to secure a simultaneous movement of :t-he same. The employment of a transformer in the manner described has several advantages. If the windings {be such that the ratio of transformation is greater (than one, or, in other words, if the secondary voltage be greater than the primary, I may employ a much smaller and less expensive condenserthan would be required if the condenser were connected direct to the armature --winding, as shown in Fig. 5. 'By varying the ratio of transformation in the manner described the capacityefiect may be variedmorecon-venientlylandthroughsmaller gradations than could :be easily attained merelyby the use-of acondenser the capacity of which isvariable step by step in the usual way.

In general the construction of a machine embodying .myin-vention would :be somewhat similar to-thatof a rotary-converter, one side of the armature beingconnected to a commutator in the usual manner and the other side .of the-armature tapped at regular intervals and connected to collector-rings, which in turn are connected to condensers or other appropriate sources of leadingelectro-motive force.

Although the invention as illustrated in Figs. -6 and.7 is shown as applied-to a bipolar Gramme-ring construction, it is obvious that it is equally applicable to machines of any number of poles and with any type of armature or armature-windin g. Consequently I do not limit myself to the exact forms shown in the drawings, either as to the number of poles, styles, or winding or number of phases used on the condenser-circuit.

What I claim as new, and desire to secure by Letters Patent of the United States, is

1. The method of impressing a magnetomotive force upon the field-magnets of directcurrent dynamo-electric machines, which consists in artificially producing phase-displaced currents in conductors movable relatively to the field-magnets.

2. The method of energizing the field-magnets of a direct-current dynamo-electric machine, which consists in setting up out-ofphase currents in the armature-winding.

3. The method of operating direct-current dynamo-electric machines, which consists in impressing on a winding movable relatively to the field-magnets an electromotive force advanced in phase over that which would normally be induced therein, and varying the value of said electromotive force.

4. The method of operating direct-current dynamo-electric machines, which consists in shifting the phase of currents in the armature-winding, and varying the angle of phase shifting in accordance with the result desired.

In witness whereof I have hereunto set my hand this 27th day of March, 1902.

HAROLD W. BUCK.

Witnesses:

WM. M. BLAIR, K. M. KELLEHER.

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