US550354A - Self-exciting constant-current alternator - Google Patents

Description

(No Model.) -3 Sheets-Sheet 1.

A. SCHMID & B. G. LAMME.

SELF EXCITING CONSTANT CURRENT ALTERNATOR. No, 550,354. Patented Nov. 26, 1895T---- (Cw-[M5565 I M Zlnwnfom I y :4 5: All,

ANDREW IGRAHAM. PHOTO-UTHO.WA5HINFTON, D50.

(No Model.) 3 Sheets-Sheet 2. ,A. SOHMID & B. G. LAMME. SELF EXCITING CONSTANT CURRENT ALTERNATOR.

No. 550,354. Patented Nov. 25, 1895? Fig.2..

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' SOHMID & B. G. LAMME. SELF EXCITING CONSTANT CURRENT ALTERNATOR No. 550,354. Patented Nov. 26, 1895.

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WINESSES: INVENTORJ I M 55 M l w z UNITED STATES PATENT OFFICE.

ALBERT SOHMID, OF ALLEGHENY, AND BENJAMIN G. LAMME, OF PITTSBURG, PENNSYLVANIA.

SELF-EXCITING CONSTANT-CURRENT ALTERNATOR.

SPECIFICATION forming part of Letters Patent No. 550,354, dated November 26, 1895.

Application filed August 24, 1891. $erial No. 403,520. (No model.)

T at whom it may concern.-

Be it known that we, ALBERT SOHMID, a citizen of the Republic of Switzerland, residing at Allegheny, and BENJAMIN Gr. LAMME,

a citizen of the United States, residing at Pittsburg, in the county of Allegheny, State of Pennsylvania, have invented a certain new and useful Improvement in Self-Exciting Alternate Oonstant-CurrentElectric Generaro tors, (Case No. 411,) of which the following is a specification.

The invention relates to a method of and apparatus for generating in an electric circuit alternating electric currents of constant I 5 quantity throughout variations in the external resistance, and maintaining the field of force of such generating apparatus by means of currents developed in the machine itself.

The invention consists, in general terms,

in supplying the field-magnet coils with currents developed in certain supplementary armature-coils which tend to deliver currents of increasing potential when the load upon the generator increases, and in connecting in z 5 series with these coils other coils in which a tendency toward an increasing potential is also developed by increments in the amount of work being performed in the armaturecircuit; but the electromotive forces developed in the two systems of coils oppose so that there is a resultant electromotive force increasing by the proper amount to maintain the requisite field of force for causing the armature to deliver a constant current to the work-circuit.

The invention relates especially to the class of electric generators described in Patent No. 418,659, dated December 31, 1889, and issued to \Villiam Stanley, J r.

The invention will be described more particularly in connection with the accompanying drawings, in which- Figure 1 is a diagram of the armature showing the coils applied thereto. Fig. 2 is a diagram showing the relation of the armature and field-magnet circuits, and Fig. 3 is a theoretical diagram illustrating the relative values of the two systems of electromotive forces developed in the two circuits.

Referring to the figures, A represents the armature-core, having poles a a a a the. Main armature-coils b 11 &c., are wound, respectively, upon the poles a to a inclusive, but are so arranged that the coils b b If U are wound in a given direction upon the alternate poles and the coils b b and b in the opposite direction upon the intervening poles. The general construction and operation of this armature for maintaining constant currents is described in the patent above referred to, and the organization is such that it tends to deliver an approximately constant current under varying loads.

For the purpose of exciting the field-magnet (represented in the diagram at F, Fig. 2) currents continuous in direction are required. For this purpose coils c are wound upon the pole a, and no main armaturecoils b &c., are wound upon this pole.

In the normal operation of the machine the number of lines of force from the field-magnet which would tend to thread the coils 0 would increase somewhat under increasing loads, and in practice the increase in the difference of potential due to such increase in the lines of force might cause the current delivered to the fieldmagnet coils to increase too rapidly as the load increases, so that it would overregulate. To compensate for such increase, the supplemental coils o c 0 &c., are wound upon the other poles of the armature, and they are connected in series with the coils c and wound in such direction that the electromotive force developed therein will be opposed to that developed in the coils c. This will produce the desired compensation and cause a resultant current to be delivered to the commutator O and through it to the field-magnet coils f, in value slightly increasing with increasing loads, so that there will be a resultant field force which will increase in value as the electromotive force required at the terminals of the main armature-coils increases by very nearly, if not exactly, the amount required to maintain a constant current upon the work-circuit \V. An adjustable resistance B may be included in the conduotor 0'', leading from the commutator-brush 1) of the commutator C to one terminal of the field-magnet coils. The successive poles of the field-magnet are of opposite polarity, as indicated by the winding and by the letters N S. The cond uctor 7 leading from the fieldmagnet coils, is connected with the brush p of the commutator C. Currents are delivered from the armature-coils b b to the work-circuit IV through the commutatonbrushes q g In the theoretical diagram, Fig. 3, the relative values of the electromotive forces are illustrated. The line marked 00 2 is a normal, above which is plotted a curve 0) g, which indicates the value of the electromotive force developed in the coil 0 during different loads upon the machine. The curve cow represents the value of the electromotive force developed in the supplemental coils c 0 &c., through variations in the amount of work being done, and the ordinates between the two curves rep resent the effective electromotive force,being the difference between the two electromotive forces, since the electromotive force in the coils c 0 &c., is opposed to that in the coils c.

It will be noticed that when no work is being done there is still a high electromotive force developed in the coils c,while no electromotive force is developed in the coils c 0 &c. This is due to the fact that the lines of force from the field-magnet tending to thread the armature-coils Z) 19 are opposed by an approximately equal number of lines of force developed by the magnetic potential due to the current flowing from the armature-coils through an external circuit of no resistance, so that no lines of force succeed in threading the coils 0 0 etc. VVhemhoweveigwork is being done in the work-circuit, the number of lines of force allowed to pass through the armature-poles a to co inclusive, gradually increases, and thus the electromotive force in the coils 0 0 &c. ,increases accordingly. The electromotive force in the coils 0, however, i11- creases at a greater rate during such time, especially because of the shifting of the relative time of the appearance of maximum magnetic polarity on the part of the pole-pieces a and its passage across the faces of the pole-pieces of the field-magnet, so that the resultant effective electromotive force may be made to increase under increasing loads to as great an extent as required for the automatic regulation of the machine.

It should also be observed that by suitable variations in the proportions of the coils the resultant exciting-current may be made to have a constant or a decreasing electromotive force, as desired in different cases.

I'Vhile the generator above described is primarily intended to be so constructed that the regulating means employed shall maintain a constant current in the work-circuit, it is to be understood that the several windings of the generator may be so proportioned relatively to each other that the regulating means described and hereinafter claimed may serve to maintain a constant potential in the workcircuit. IVe therefore do not desire to limit our invention to the particular function of our means of regulation, whereby mainte nance of a constant current in the work-cin cuit is effected.

WVe claim as our invention 1. The combination with the field magnets of an electric generator, of an armature having radiating poles, main armature coils wound upon certain of the poles and delivering currents to a work-circuit, field-exciting coils wound upon the remainder of the poles, a commutator with which the field exciting coils are connected, field magnet coils having circuit connections with the commutator, and opposing supplemental coils wound upon the other poles and connected in series with the first-named field exciting coils.

2. In an electric generator the combination of the armature core A, having the work cir* cuit coils b, b wound upon certain of its poles, field exciting coils c wound upon the other poles and opposing field coils 0, c &c.,wound upon the same poles with the coils Z), t and connected in series with the coils c, substan tially as described.

3. In a self-exciting electric generator, the combination of a polar armature having certain of its poles provided with work-circuit coils, other of its poles supplied with field exciting coils, and compensating or opposing field-exciting coils applied to the first named poles and connected in series with the fieldexeiting coils, substantially as described.

4:. The combination with the field-exciting coils of an electric generator, of compensating or opposing coils on the armature connected in series therewith and developing a counter potential, substantially as described.

5. In a self-exciting electric generator the combination with an armature having radiating pole pieces with overhanging lugs, of work circuit coils placed upon certain of the poles beneath said lugs, field exciting coils placed upon other of said poles and means for generating electromotive force opposing that developed in the last-named coils, in value varying with the electromotive force developed in the work-circuit coils.

6. In a self-exciting electric generator the combination with the work-circuit coils, of coils generating electromotive force increasing in value with increments in the work be ing done, and coils generating electromotive force opposed to that developed in the lastnamed coils and also increasing in value with the increments in the work being done.

7. In a self-exciting electric generator the combination with the work-circuit coils, of main field exciting coils generating electromotive force increasing in value with. increments in the Work being done, and coils gensubscribed our names this 24th day of Sep- ALBERT 'SOI-IMID. BENJAMIN G. LAMME. \Vitnesses J. W. TATE, Jr., J. W. SMITH.

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