US1118633A - Automatic voltage-regulator. - Google Patents

Description

Gr A. BURNHAM. AUTOMATIC VOLTAGE REGULATOR. APPLIGATION FILE-I) JULY 16, 1910; gmmwlzn'oo'r. 10, 1914.

1,1 18,633, Patented Nov. 24, 1914.

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- GEORGE A BURNHAM, OF CLIFTONDALE, MASSACHUSETTS.

AUTOMATIC VOLTAGE-REGULATOR.

Application tiled Ju1y'16, 1910, Serial No. 572,314. Renewed October To all'wkom it may concern Be it known that I, GEORGE A. BURN- HAM, a citizen of the United States, and resident of Cliftondale, in the county of Essex and State of Massachusetts, have invented an Improvement in Automatic Voltage-Regulators, of which the following description, in connection with the accompanying drawings, is a specification, like letters on the drawings representing like parts.

To regulate the terminal voltage of gen- ,the field current, and this has been accomplished by means of interrupting the field circuit of the generator, or by excluding and including periodically an additional fixed resistance in series with the usual field resistance.

lVhen the entire field circuit is opened a. powerful change of field strength is effected and vicious sparking or arcing results from the field discharge which renders these methods too heroic to be satisfactory in practice, and they have not therefore proven successful. When a fixed resistance in series with the field winding is employed the regulating devices must be of a character which will permit a delicate response'to the conditions of the external circuit, otherwise the regulating parts will overshoot the proper degree of. movement and fail in their intended effect in maintaining constant voltage.

My invention is designed to effect as prompt'and sensitive a regulation as either method could afiord without incurring the deleterious arcing from sudden and great changes of field strength and without incurring jerky and irregular regulator movements; I effect this by employing a makeand-break device constantly operating to shunt a moderate field resistance, said device constantly operating under powerful magnetic control which is extremely sensitive to minor voltage variations, and I provide a hand-switch for adjusting thefield resistance to permit it to act to best advantage under wide ranges of load in the'main circuit. Also I secure quick action 'for varying-the proportion of the make. with relation to the break, in the make-and-break device, by providing means independent of the voltage being regulated to coiiperate with the voltage-responsive mechanism in a giving the make-and-break device extreme Specification of Letters Patent.

it is usual to vary the strength of I ness and quickness of Patented Nov. 24, 1914.

16, 1914. Serial No. 867,035. sensitiveness. The make-and-break device preferably consists of two contact members, one of which is responsive to two separate influences, one the changes in voltage in the main circuit which is being regulated, and the other independent of said changes in voltage. Preferably the make-and-break de vice is of the type in which one member contains a. conducting section and an ins ulated section and is rotary, or at least continuously movable, at practically constant speed, and the other member has continuous vibratory movement with relation to said movable or rotary member, and I provide mechanism for varying the throw or vibration thereof, consisting of two separate means, preferably comprising an electromagnetic actuator and a quick-acting actuator, such as a spring, ooiiperating with said electromagnetic actuator to give stea dimake-andbreak action and to prevent tendency of the vibrating member to overthrow or to be moved by the mechanism.

In the drawings, I have shown diagrammatically a preferred embodiment of the invention.

For convenience of illustration, I have shown a generator 1 whose mains 2, 3 supply lamps or other translating devices 4. The field 5 of said generator is under the control of a rheostat or variable resistance 6, such as usually employed for regulating the voltage of a generator or the speed of a motor. The form of make-and-break device herein shown comprises a rotary cylinder 7 divided diagonally into a conductor section 8 and an insulated section 9, said cylinder being rotated any suitable means, as by a motor 10, lterein shownf as supplied with energy from any suitable source, as for convenience supplied from the mains 2, 3by conductors .11, 12. Cooperating with the cylindrical contact member 7 is a brush contact 13 whose vibrating arm 14: is pivoted at 15. An-arm 16 therefrom is connected at'l7 to the core 18 of an electromagnet whose winding19 may be supplied IL with energy from any source of power, shown for convenience as -connected to the mains 2-, 3 by wires 20, 21-, a resistance 22 being interposed in the wire 21. A spring 23 normally tends to overpower the electromaghet when deener'gized or to hold the contact arm 14in opposition to the electromagnet, and a dash=pot 24 is preferably provided to prevent too great an amplitude of movement of the arm 151 under the influence of said spring. A contact-making voltmeter serves to control the electromagnet, being herein shown as comprising an electromagnet 25 connected across the mains by conductors 26, 27 (a resistance 28 being interposed in the latter), the core 29 of said electromagnet operating a contact lever 30 pivoted at 31 and having a movable contact 32 to cooperate with a fixed contact 33 connected by a wire 34: to the conductor 21, the conductor 20 being connected by ayvire 35 tosaid lever, preferably at the pivot 31 and said lever Qbeing nortnally held in practically floating or balanced position by a spring 36 so as to have extreme sensitiveness of make-and-break a'ctlon' 1n response to its electromagnet 25. make-and-break ac tion opens and closes a short circuit for the brush operating, coil119, providing a powerhi1 and sensitive adjustment for the brush which makes its action reliable under the drag of the rotary interrupter 9. Cooperating with the rotary contact member 7 is a brush 37 connected by a wire 38 to the arm 35,

39 ofthe rheostat, the other terminal of the rheostat being connected by a wire 40 to the conductor arm 1 1 of the vibrating contact member, and a condenser 41 being connected across the wires 38, 40. The condition is preferably such that when the voltage is constant in the main line circuit, the contact-making portion of the volt-meter, i. e. the lever 30, is floating, by which I mean that the'contacts 32, 33 are in such a sensitive or balanced relation that they may be said to be open or to be closed, as either relation may then exist. The result is that the arm 14 is maintained in a constant state of vibration as the cylinder 7 rotates. It now the load 4 isincreased so that the voltage lowers in the main circuit, the contact 32 will be maintained closed, thereby demagnetizing the electromagnet 19, whereupon the spring 23 instantly tends to shift the brush 13 to the left thereby momentarily increasing the duration of shortcircuit of the rheostat in the field circuit of the generator, which increases the current in the field and raises the voltage in the main circuit,and when said voltage reaches normal the contacts 32, 33 open, thereby energizing the electromagnct 19 and moving the brush '13 back to the right in opposition to the spring 23 and dashpot 24. This causes the i eostat tobe short circuited for a shorter the generator duration at each rotation of the cylindrical contact member 7. The constant vibration in the main circuit maintains a corresponding constant vibration of the brush 13.

It is awell known fact that the current cannot rise instantly in the field circuit of Consequently the arm 14 would move too far or overreach its proper position it said arm were equally balanced or floating, as would be the case if the arm were dependent for all itsmovement simply on the energizing and deenergizing of electromagnetic control, and accordingly to give quickness, sensitiveness, and accuracy of movement and prevent the efiect of this oven-caching or tendency to overreach, I provide the spring 23 (and preferably the dash pot 21) which tends at all times to move the brush 13 and arm 14 to the left so as to give quickness in overcoming their movement to the right. This prevents the brush from remaining in the overreaching position (as it otherwise would fects, the latter being the well-known pumping eifects, commonly experienced with one solenoid only which is energized directly from the mains. By my combination, I establish a vibration, which, notwithstanding that its maximum in either direction extends to the improper position of the brush, is so quick in action that its over-reaching effect is practically lost or eliminated (because of its quickness of movement and the magnetic sluggishness of the field) and the operative influence thereof is simply that of the mean or intermediate half. The arm 14 and its brush are vibrated constantly even though the voltage is at normal, but inasmuch as the return movement is rendered quick and instantaneous by the spring 23 the resultant current in the field is not determined by either of the extreme positions of the brush but by the intermediate or average position. If the entire back and forth movement of the brush were determined solely by electromagnetic operating or shifting. means, the time required tomove the brush would be dependent uponthe comparatively long length of time required for energizing and deenergizing theelectromagnetic means, which is necessarily slow because of inductance and also because of the time required for the voltmeter to operate.

on account of its inductance.

WVhenever there is a change of voltage in the main line, the contacts 32, 33 either remain closed or remain open until the voltage has been restored in the main line. This re sults in changing the position of the brush 13 lengthwise of the cylinder 7 or in other words changes in voltage in the main line cooperate with the normal vibratory movement above explained, to produce a variable vibration or variable length of vibration and also to cause the brush 13 to assume said different positions longitudinally of the contact member 7, thereby varying the duration of the break with relation tethe duration of the make in the make and break device.

In further explanation of the importance of myinvention, I secure accuracy by employing the voltmeter therefor and power by employing the electromagnet therefor, as

distinguished from attempting to provide both accuracy and power by means of the same electromagnet (still greater accuracy being secured by combining a spring action with-the power actuating electromagnet, as already explained), in connection with the continuous short circuiting of the field rheostat. By

short circuiting this adjustable rheostat 'I eliminate the vicious and destructive sparking and also bring the intensity of sparking'under the direct control of theoperator, as already explained.

Having described my invention, what I claim as new and Patent is,

In a voltage regulator, the combination of a generator having a shunt .field, a constantly operating motor-driven interrupter in a shunt around a portion of the field resistance, said interrupter having an oblique cylindrical contact to effect a" variable interdesire to secure by Letters val of the shunt closure, a voltage magnet GEORGE A. BURNHAM.

WVitnesses:

GEO. H. MAXWEL EDWARD MAXWELL.

Copies of this patent may be obtained for five cents eacli, by addressing the Commissioner of Patent Washington, D. C.

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