US798237A - Controller for alternating-current motors. - Google Patents

Description

No. 798,237. PATENTED AUG. 29, 1905. H. L. VAN VALKENBURG. CONTROLLER FOR ALTERNATING CURRENT MOTORS.

APPLICATION FILED SEPT. 2, 1904:.

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UNITED STATES PATENT OFFICE.

HERMON L. VAN VALKENBURG, OF PITTS'BURG, PENNSYLVANIA, AS- SIGNOR TO WESTINGHOUSE ELECTRIC 8: MANUFACTURING COM- PANY, A CORPORATION OF PENNSYLVANIA.

CONTROLLER FOR ALTERNATlNG-CURRENT MOTORS.

Specification of Letters Patent.

Patented Aug. 29, 1905.

Application filed September 2, 1904. Serial No. 223,138.

To all whom it may concern:

Be it known that I, HERMON L. VAN VAL- KENBURG, a citizen of the United States, and a resident of Pittsburg, in the county of Allegheny and State of Pennsylvania, have invented a new and useful Improvement in Controllers for Alternating-Current Motors, of which the following is a specification.

My invention relates to controllers for alternating-current-translating devices; and it has for its object to provide means for supplying variable voltages to such devices which will prevent destructive and dangerous arcing between the stationary and movable contact-terminals.

The single figure of the accompanying drawing illustrates a controlling device constructed in accordance with my invention.

In the preferred form of my invention the opposite terminals of a suitable source 1 of alternating-current energy are respectively connected to the middle points or approximately the middle points 2 and 3 of noninductive resistances 1 and 5. The terminals 6 and 7 of the resistance 2 are respectively connected to the corresponding terminals of autotransformer-windings 8 and 9, the other terminals of which are respectively connected to terminals 10 and 11 of the resistance 5.

The autotransformer-windings 8 and 9 are subdivided by means of leads 12 13 1 1 15 16 17 18 19, &c., which are respectively connected to stationary contact-terminals 2O 21 22 23 24 25 26 27, &c. The leads 12 and 13 connect with corresponding points in the autotransformer-windings 9 and 8, respectivelythat is, so that equal numbers of turns are included between the points of connection of these leads with the said windings and the terminals thereof. Leads 15 and 16 and leads 18 and 19 are similarly connected to corresponding points. Lead 1 1 is connected to autotransformerwinding 9 approximately midway between the points of connection of the leads 12 and 16, and the lead 17 is connected to the autotransformer-winding 8 approximately midway between the points of connection of the leads 15 and 19. The remainder of the windings are similarly subdivided, substantially as shown.

One terminal of a motor or other suitable translating device 28 is connectedito the point 2 of the resistance 4 and the other terminal to a movable brush 29, which is adapted to make contact with the stationary contact-terminals 2O 21 22, &c., the dimensions of this brush being such that when the controller is in operation it shall engage at least one of the stationary terminals, but never more than two at a time.

In the operation of my invention the brush 29 engages the stationary contact- terminals 20 and 21 in its first position, the motor-circuit then being established through the brush 29, contact- terminals 20 and 21,in parallel through the respective portions of the autotransformerwindings 8 and 9 which are included between the points of connection of the leads 1?) and 12 therewith and the terminals of the resistance 4, and in parallel through the halves of the resistance 4. This is a normal running position of the controller and is designated by the letter R, as are the succeeding running positions. In the next position of the controller, which is a transitional position, the brush 29 engages the contact- terminals 21 and 22 and the motor-circuit remains practically the same, except that the portion of the autotransformer winding 9 which is in circuit contains more turns than the portion of the autotransformerwinding 8which is in circuit. Consequently a local circuit is established through the contact-terminal 21,brush 29,contact-terminal 22, the portion of the autotransformer-winding 9 which is included between the point of connection of the lead 14 therewith and the terminal 7 of the resistance 4:, resistance 4 and the portion of the autotransformer-winding 8 which is included between the terminal 6 and the lead 13. The current which flows in this local circuit is due to the dilference of potential resulting from the excess of the number of turns in that portion of the autotransformerwinding 9 which is in circuit over that portion of the autotransformer-winding 8 which is in circuit, and the resistance to the flow of this current is that in the resistance element 4. In the next position of the controller, which is also a transitional position, a similar action occurs, though the current in the local circuit is in the opposite direction. It is noticed that the resistance to the flow of the current in the local circuit is the entire amount included in the resistance element 4, whereas under normal running conditionsthat is, when the brush 29 occupies one of the positions R-the resistance in each of the parallel circuits through the transformer-winding is only one-half of the resistance element that is, under normal operating conditions the resistance loss is only one-quarter of that which occurs when the controller is in one of its transitional positions.

While I have shown the autotransformerwindings 8 and 9 as mounted upon the same iron core 30, it is to be understood that these windings may be placed upon separate cores. The resistances 4 and 5 may also be inductive resistances, and the resistance may be embodied in the end portions of the autotransformerwindings, if desired, though it will generally be found most practical to have them separate, as shown in the drawing. The controller may also be arranged so that when it is in its running positions only one of the autotransformer-windings shall be in circuit, the other one being employed merely as an auxiliary windingthat is, as a winding which shall aid in preventing injurious arcing at the contact-terminals when changing from one position to the other in a manner similar to that here shown.

My invention may also be capable of other variations in the details of construction and arrangement, and I do not wish it limited in any respect, except by such restrictions as may be imposed by the prior art.

I claim as my invention 1. The combination of a source of electrical energy, resistances having their middle points respectively connected to said source, subdivided autotransformer-windings connected between the terminals of said resistances, a translating device or devices having one terminal connected to the middle of one of said resistances and means for connecting the other terminal to the various points of subdivision of the said autotransformer-windings.

2. The combination of a source of electrical energ resistances having their middle points respectively connected to said source, subdivided autotransformer: windings connected between the terminals of said resistances, a translating device or devices connected between the middle of one of said resistances and points of subdivision of the said autoto intermediate points in the said inductive point of one of said resistances and means for connecting the other terminal with any two of said leads.

4. The combination of a source of energy, resistances having their middle points respectively connected to said source, autotransformer-windings connected between the terminals of said resistances. stationary contactterminals the first and second, fourth and fifth, &c., of which are respectively connected to corresponding points in the autotransformerwindings and the third, sixth, &c., of which are connected alternately and consecutively to the autotransformer-windings intermediate the other leads, a translating device or devices having one terminal connected to the middle point of one of said resistances and means for, connecting the other terminal with any two of said leads.

5. The combination of a source of. electrical energy,subdivided autotransformer-windings having their terminals connected thereto, a translating device or devices having one terminal connected to one pair of terminals of the said autotransformer-windings, and means for connecting the other terminal to points of subdivision of said windings.

6. The combination of a source of electrical energy,subdivided autotransformer-wind ings having their terminals connected thereto, the end portions of said windings containing a definite amount of resistance, a translating device or devices having one terminal connected to one pair of terminals of the said autotransformer-windings and means for connecting the other terminal to points of subdivision of said windings.

7. The combination of a source of electrical energy, resistances having points intermediate their terminals respectively connected to said source, subdivided autotransformer-windings connected between the terminals of said resistances, a translating device or devices connected between the middle of one of said resistances and points of subdivision of the said autotransformer-windings.

8. The combination of a source of electrical energy, non inductive resistances having points intermediate their terminals respectively connected to said source. subdivided autotransformer-windings connected between the terminals of said resistances, a translating device or devices connected between an intermediate point in one of said resistances and points of subdivision of the said autotransformer-windings.

9. The combination with two inductive windings and resistance members connecting corresponding terminals thereof, of an alternating-current generator having its terminals respectively connected to intermediate points in said resistance members, a translating device having one terminal connected to an intermediate point in one of the resistance members, and means for making progressive con- IO and means for connecting the other terminal successively to points of subdivision of said windings that are symmetrically and unsymmetrically located.

In testimony whereof I have hereunto subscribed my name this 23d day of August, 1904:. I 5

HERMON L. VAN VALKENBURG.

Witnesses:

O'rTo S. SOHAIRER, H. A. SoHAUB.

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