US412700A

US412700A - And polly craig

Info

Publication number: US412700A
Authority: US
Publication date: 1889-10-08
Anticipated expiration: 1906-10-08

Description

(No Model.)

W. H. ELKINS.

REGULATOR FOR DYNAMO ELECTRIC MACHINES.

No. 412,700. Patented Oct. 8, 1889.

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UNITED STATES PATENT OFFICE.

\VILLIAM H. ELKINS, OF CAMBRIDGE, MASSACI'IUSETTS, ASSIGNOR OF TIMO- THIRDS, BY DIRECT AND MESNE ASSIGNMENTS, TO ARTHUR B. GRIGGS, OF BOSTON, MASSACHUSETTS, AND POLLY CRAIG, OF DE FUNIAKSPRINGS,

FLORIDA.

REGULATOR FOR DYNAMO-ELECTRIC MACHINES.

SPECIFICATION forming part of Letters Patent No. 412,700, dated October 8, 1889. Application filed January 18, 1889. Serial No. 296-753. (No modeh) To all whom it may concern:

Be it known that 1, WILLIAM HENRY Ema ms, of Cambridge, in the county of Middlesex and State of Massachusetts, have invented a new and useful Regulator for Dynamos, of which the following is a specification, reference being had to the accompanying drawing, which is a diagram illustrating my invention, the pole-pieces and cores being shown in dotted lines, and the circuit which constitutes the main novelty being shown in full lines.

Myinvention relates to regulating the current in the work-circuit of a dynamo and it consists in a novel compound dynamo-circuit differing materially from all other dynamocircuits known to me, as will be now fully explained.

In the drawing, A represents the armature, and a the commutator, of an ordinary dynamo; B, the positive brush, and B the negative brush, and B an additional brush, The workcircuit is from additional brush B through lamps L and field F F, to main brush B. The regulating-circuit is from brush B, through resistance R, to its junction 1) with the workcircuit.

In practical operation the resistance in the work-circuit B L F F B is constant, excepting as it is varied by varying the load, as by introducing a different number of lamps L, and in the diagram I have shown five lamps or groups of lamps, so that the variable load may be divided into five portions. It will be found that the brush B may be so adjusted in any given dynamo with a given speed that the desired current will be maintained over the work-circuit B L F F B when only one lamp out of the tivethat is, one-fifth of the Variable loadis used, the regulating-circuit B R bbeing' then open, or, what is practically the same thing, the resistance R being very large. Under these conditions, if a second lamp, or anotherlifth of the load, beintroduced into the work-circuit B L F F B, the current in the work-circuit will be decreased, for the speed of the dynamo and electro-motive force remain the same; but the resistance or load L is doubled, and consequently the two lamps L, or two-fifths of the total number of lamps,

will not be at full candle-power. To remedy this the electro-motive force of the work-circuit B L F F B must be increased. An ammeter in the worlccireuit B LF F B will indicate when the current in the work-circuit is thus decreased by the introduction of another fifth of the load, and the regulating-circuitB R Z) will then be closed through resistance R, thus establishing a regulating-current through the circuit B R Z) L F F B, this additional current bringing up the current in the work circuit to the proper standard. \Vhen a third fifth of the load L is introduced, the current in the work-circuit again decreases, and is again brought to standard by aid of the regulating-circuit by still further decreasin g the resistance R, and so on until the whole load is in the work-circuit, when the resistance R is eliminated, or practically so, the work-circuit being then from brush B to brush B practically as if the brush B and the re- 7c then open, or practically so, and that as the resistance R-in the regulating-circuit is decreased the difiference in potential between B and Z) diminishes, there being but slight difference in potentialbetween B and b with about four-fifths of the load in the work-circuit, while with full load in the work-circuit and the resistance R decreased to practically nothing there will be a current from Z) to B instead of a current from B to b, as is the case when three-fifths or less of the full load is in the work-circuit. In theory under the minimum load-say one-fifth of the full load there should be no current in the regulatingcireuit for the best results, and the additional brush B should be set to give the desired current in the worlecircuit when the load is at the minimum, and then be drawn toward the brush B after, say, about one-half of the full load is introduced into the work-circuit, in order to prevent any possibility of a current from b to 13 but, as will be clear, a second additional brush might be used between B and B, where a closer degree of regulationsay from sixty lamps to only one or two-was required; or brush B may be moved toward B as indicated by dotted line B In practice I have succeeded in maintaining acon stant current in the work-circuit, although the load varied from one-fifth to fourfifths, the current from B to I) being with one-fifth load, and with the regulating-circuit open, the same, of course, as in the workcircuit; but with two-fifths load in the workcircuit the current from B to 1) decreased and the current from B through R to I) increased, and soon, until with four-fifths load there was no current from B to b, and the current from Bthrough R to b was the same as that in the work-circuit; but, as before observed, in this case under full load the current from B through R (B being then reduced to practically nothing) to Z) was greater than the current in the main circuit, and the excess flowed from b to B and back through the coils of the armature to B. This backflow of a portion of the current is not desirable, and can readily be prevented by moving the brush B nearer to the brush B, or by the use of brush B, as indicated by B It will be clear to all skilled in the art how the resistance B may be adjusted, and therefore no means are described or shown in the drawing.

What I claim as my invention is- In combination with the armature A and its commutator a, themain brushes B B',the additional brush B and the adjustable resistance R, the brushes B and B being connected to the work-circuit at b, with the resistance R between the brush B and the junction 17, all arranged and operating as described to keep the current constant by variations in the current supplied by the brushes B and B, substantially as described.

. WILLIAM H. ELKINS,

WVitnesses:

EDWARD S. BEACH, J OHN R. Snow.