US2308925A - Current-voltage regulator - Google Patents

Description

Jam 11.9 1943. w. KEHSE ETAL. 2,308,925

CURRENT VOLTAGE REGULATOR Filed March 4, 1940 Fly J nvvwmms Maren/vs Ire-use, @arrrmza mus/mm;

Patented Jan. 19, 1943 UNITED STATES PATENT OFFICE CURRENT-VOLTAGE REGULATOR Application March 4, 1940, Serial No. 322,230 In Germany February 22, 1939 4 Claims.

This invention is directed to the regulation of electrical systems. More specifically. the invention is directed to the regulation of both the voltage and current in an electrical circuit in order to safeguard the circuit against sudden overloads.

Heretofore it has been known to regulate electrical systems either from current control devices or voltage control devices. It is also known to use carbon pile regulators as the control means. However, these devices have not been fully satisfactory inasmuch as they do not give the greatest accuracy of regulation, especially up to and at the point where serious overloading of an electrical circuit occurs.

It is an object of the instant invention to provide a regulating means for an electrical circuit so that the voltage-current characteristic of the generator remains substantially horizontal up to the point of overload and then is suddenly dropped.

Another object of the invention is to provide a voltage-current regulation of an electrical circuit by means of specially designed carbon piles and regulating devices so that an extremely accurate regulation is obtainable.

Another object of the invention is to construct a carbon pile regulator which remains substantially dormant up to the point of overload, and after such point quickly increases its resistance and regulating effect.

Generally the objects of this invention are obtained by incorporating into the electrical circuit between the generator and consumer a regulating device consisting of specially designed carbon piles. One of the carbon piles is responsive to voltage changes, while another pile is responsive to current changes and at the point of overload reacts to activate further the voltage responsive pile. In this combination, upon a current increase in the circuit, the voltage is caused to be decreased thus cutting down the current supply. Consequently a substantially horizontal current-voltage curve can be maintained up to the point of overload and then the regulation becomes effective to cause a sudden drop of this current.

The means by which the objects of the invention" are obtained are more fully described with reference to the accompanying drawing, in which:

Fig. 1 is a graph of current-voltage curves showing the application of the invention;

Fig. 2 is a diagrammatic, cross-sectional view of the construction of the carbon pile regulator used in the invention;

Fig. 3 is a diagrammatic view of the current voltage regulator applied to an electrical circult;

Fig. 4 is a view similar to Fig. 3, but showing a modification of the circuit; and

Fig. 5 is a graph indicating the range of current response in the device of Fig. 4.

In Fig. l a current-voltage graph is shown with the ordinate E representing the voltage and the abscissae I the current. A constant voltage is indicated by the straight line curve A parallel to abscissae I. The curves B and C are illustrative of the current-voltage control obtained by devices heretofore known in the art. Electrical generators should deliver a uniform voltage, which is maintained uniform by automatic regulating devices. With known regulating devices, generators are endangered by sudden consumer overloads. As shown by the curves B and C, the voltage under prior regulating devices is not maintained substantially constant up to the point of overload, and does not drop oil suddenly upon the appearance of an overload. According to this invention the voltage is maintained constant up to the point of overload, as shown by the curve D, at which point the voltage drops suddenly, and thus protects the generator.

A carbon pile regulator which will give a control as illustrated by curve D is shown in Fig. 2. This carbon pile regulator consists of superimposed carbon discs S held between upper end plate J and the end of tube Z which has an enlarged opposite end E. Mounted within this enlarged end is a spring bearing upon a shoulder intermediate the spring and the carbon discs. Wire F spans the discs S and spring and is normally held taut between end plates J. Consequently the spring and wire F hold discs S in compression and at low resistance.

In operation wire F is connected in series with the electrical circuit to .be regulated. The wire is selected with a coefllcient of expansion such that on being heated it will lengthen a predetermined amount. However, because of the spring, the expansion of wire F will not materially change the compression, and consequently the resistance of, discs S. This holds true until wire F lengthens to a point where the lower end plate J contacts the lower end of tube Z, as then the spring ceases to function. Further slackening of the wire F allows the pressure on discs S to become suddenly released, thus greatly increasing the resistance of the unit. According y. the wire F can be heated up to the point of overload without substantially changing the resistance of the unit because of the spring, and the horizontal portion of curve D, Fig. 1, is produced. At the point of overload, wire F slackens against the end of tube Z, and the sudden drop of curve D is obtained.

The regulator of Fig. 2 can be adjusted for the point at which wire F slackens by providing an adjustable abutment screw in the end of tube Z. As shown by the curves of Fig. 5, as the screw is turned inwardly the wire F will slacken at lower current values, and vice versa.

Figs. 3 and 4 diagrammatically illustrate the use of the device of Fig. 2 in an electrical circuit. In Fig. 3, H represents the wire F of Fig. 2, and K the carbon discs S. As shown the wire and discs are connected in series with the line leading from the generator (not shown) to the consumer load V. Between wire H and the generator there is located a second carbon pile regulator i also not shown) the resistance of which is controlled by the armature D of magnet M. Voltage coil on magnet M is in series with resistance W. and connected in parallel with the circuit between the generator and consumer V. Current coil St on magnet M is shunted across carbon pile K.

In operation, the coil Sp is responsive to voltage changes in the circuit between the generator and consumer, and through magnet M actuates armature D to regulate the unshown carbon pile, whereupon voltage regulation is obtained. Current flowing through wire H heats the same, and i in accordance with the design of the regulator of Fig. 2, at first does not materially change the resistance of carbon pile K. However when the consumer load reaches the point of generator overload, the resistance of pile K is suddenly in creased thus causing an increased current flow through coil St. Magnet M is consequently energized to actuate armature D, and the unshown carbon pile has its resistance increased so that less current at a lower voltage is supplied to the ccnsimier. Of course, the direction of magnetic force in magnet M is selected so as to produce the desired direction oi operation of armsture D.

In Fig. 4, coils Sp and St of Fig. 3 are in eflect combined into a single coil Sp. Wire H is in series with the consumer line, but carbon pile K is in series with resistance W and shunted across coil Sp. As in Fig. 3, coil Sp is responsive to the voltage of the consumer line. Pile K acts, upon overheating oi wire H, to cause a greater current flow through coil Sp, and thus regulation of both the current and voltage is obtained as in Fig. 3.

It is apparent that a very desirable currentvoltage regulation is obtained by the invention. Because of the novel construction of the carbon pile shown in Fig, 2, a substantially constant voltage can be maintained by the circuits of Figs. 3 and 4 as shown by the substantially horizontal portion of the curve D, Fig. 1. At the point of generator overload, the increased current heats the wire H, or F of Fig. 2, so that the spring becomes inoperative and the resistance suddenly increased to produce the abrupt downward break in curve D. The combined current-voltage control therefore enables a. regulation which has not heretofore been available to the art.

We claim:

1. A regulating device for an electrical circuit comprising a .carbon pile composed of a plurality of carbon discs, a spring loaded wire for holding said discs under compression, and means for limiting the spring expansion or elongation of said wire, means for coupling said wire in series with said circuit, a regulating motor, and means coupling said discs in parallel with the field coil of said motor.

2. A regulating device as 'in claim 1 further including a second field coil for said motor, and means for coupling said second field coil in series with said circuit.

3. A regulating device as in claim 1, and means for coupling said discs in series with said circuit.

4. A regulating device as in claim 1, and. means for coupling said discs in parallel with said circuit,

WOLFGANG KEHSE. GOTI'FRIED HILLBRAND.

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