US538670A - Electric transfer-switch - Google Patents

Description

(No Model.)

A.EKSTR5M.

ELECTRIC TRANSFER- swmm.

No. 538,670. Patented May 7, 1895.

3 H 0 t i 0 O- Q m 0 O Y, a o o 4 E V M NEEEEE. INJENTm fllrmw M 6% UNITED STATES PATENT OFFICE.

AXEL EKSTROM, OF LYNN, ASSIGNOR TO THE GENERAL ELECTRIC COMPANY, OF BOSTON, MASSACHUSETTS.

ELECTRIC TRANSFER-SWITCH.

SPECIFICATION forming part of Letters Patent No. 538,670, dated May '7, 1895.

Application filed September 7, 1893. Serial No. 84,962. (No model.)

$0 6055 whom it may concern.-

Be it known that I, AXEL EKSTROM, a citizen of the United States, residing at Lynn, in the county of Essex and State of Massachusetts, have invented a certain new and useful Improvement in Electric Transfer-Switches, of which the following is a specification.

My invention relates to electric switches, and consists in an improvement in devices of the kind known as transfer-switches, that is, switches by means of which a circuit containing translating devices can be connected to any of a plurality of generators or sets of generators at a power station or source of supply. The switch which has been most commonly used forthis purpose is that known as the jack knife switch, which is so well known as to require no further definition.

My invention consists in an improvement over this form of switch and embodies details of construction whereby the switch is more readily operated and the danger of injury to the apparatus orthe operator by arcing at the contacts is obviated.

In carrying out my invention I provide a thick plate or base of refractile, non-pliable, insulating material, such as slate, on one side of which are arranged the terminals or contacts of the switch, as will be hereinafter more fully described, and on the other side the operating handle which turns a shaft carrying the movable contacts, said shaft passing through said base and turning in a suitable bearing provided therefor. In this manner the operators hand is absolutely protected against injury by arcing at the contacts, and the handle may be so arranged that a simpler and easier movement suffices for the operation of the switch than in the jack knife switch above mentioned.

In the accompanying drawings, Figure 1 is a plan view of the switch, showing the circuit connections; and Fig. 2 is a side elevation of the same.

Referring to Fig. 1 the terminals A and A are permanently connected respectively to the positive and negative wires of a circuit, 1, 2, containing translating devices 3. These terminals consist of plates in planes parallel to that of the base-plate D, and are held in position by supports E riveted or otherwise fastened in said base-plate. The contactplates forming these terminals are not in the same plane, the terminal A being further removed from thebase-plate D than the t-erminal A. The object of this arrangement will be hereinafter more fully described. Corresponding to these terminals are two other sets of terminals B and B and O and C permanently connected respectively to the positive and negative bus-bars of generators, sets of generators or other current sources, X and Y. Of these last named terminals B and O are in the same plane as A, as best shown in Fig. 2. In other words all the positive terminals are in one plane and all the negative terminals in another. The switch proper, whereby electrical connection is effected between the said terminals, comprises two bars F, and F, having riveted, screwed, or otherwise fastened at their ends brushes or similar contact devices f, adapted to connect with the said terminals. In the position shown in the drawings, one of the said bars F connects terminal A to terminal B and the other connects terminal A to terminal B. The current-source X is thus connected to the circuit 1, 2, while the currentsource Y is open-circuited, as will be readily seen by reference to Fig. 1 without further description. The said bars F F are fastened to opposite sides of a plate f, preferably bent a little to one side of the middle, as shown in Fig. 2, so as to separate the said bars by a space somewhat greater than the thickness of the plate. One ofsaid bars is thus brought into the plane of and adapted to connect with the terminals A, B, C, while the other is in theplane of terminals A, B, O. The said platef is carried by a shaft f and has a bearing in a bushing f which passes through the base D and is secured by a nut or screw-cap J. A. handlef which may be of any suitable shape, preferably bent as best shown in Fig. 2 is attached to said shaft on the outer side of the base D for the operation of the switch. If now the handle be moved from the position shown in Fig. 1 through an arc of one hundred and twenty degrees, the bars F and F; with their brushesf will be transferred from the terminals B and B to the terminals 0 and O, at the same time changing their position with relation to the terminals A and A so that the end ,of the bar F which is shown as engaging with terminal B will pass around until it engages with A, while the end shown as engaging with A will pass around until it touches C. Thus the terminal A is connected to 0 instead .of to B, and in the same manner the'bar F connects A and 0 instead of A and B. When the switch is in this position the current source Y is connected to the circuit 1, 2, while the source X is out of circuit. It will be seen that in effecting this change the bar F which is in the same plane with terminals A, B.

and 0 passes under terminal 13 at one end and terminal 0 at the other, while in the same way the bar F passes over terminals B and O. In order to prevent the possible springing across of an arc between these contact points thus brought into proximity, I provide thin plates or septa Gand G of insulating material below the bar F and above the bar F respectively. These plates or septa are also fastened to the plate f, by means of screws f, and said screws may also serve to fasten the bars F and Fas shown. The septa, therefore, move with the said bars, and as said bars pass the terminals with which they are not adapted to'engage, the septa come between said bars and said terminals, thus preventing the formation of an arc. In order that the switch may be positive in its action, I provide on the shaftf" acamf against the surface of which bears a roller or slidef As the handle f is operated, the said cam pushes against said roller which is acted upon by a spring f. The cam is so shaped that when the switch is half way between its oper ative positions the apex of said cam is acted on by the spring, so that when the central position is passed in either direction the said spring tends to actuate the switch until the operative position is reached. The said spring may conveniently be seated, as shown in a recess or pocket f in the casting which forms the bushing but this is obviously not essential. Lugs f at the ends of the cam limit the movement of the switch and prevent it from going beyond the terminals with which it is desired to make contact.

In the drawings, Fig. 1, plug switches H are shown on the generator circuit X and Y, which may be used, if desired, in connection with the transfer switch which forms the subject of my invention. The brushes, or 'contact-devices f are shown as made up of layers of thin plates or laminze which may be of copper or any good conducting material riveted or screwed, as described, to the arms or bars F and F and embracing the terminals A, A, &c., as good electrical contact capable of taking care of large currents is thus effectively secured. It is not, however, essential that these brushes should be made in this way, as any good electrical contact device may be employed. Other modifications moreover,

might be made in the arrangement of the apparatus,'and I do not therefore intend to limit myself to the exact construction shown in the drawings, but only to the essential features thereof as set forth in the following claims.

Having thus described my invention, what I claim as new, and wish to protect by Letters Patent of the United States, is

1. In an electric switch, the combination with a set of terminals connected respectively with the positive wires of a work circuit and two or more sources of current, of a corresponding set of terminals connected to the negative wires of said work-circuit and said sources of current, all of said positive terminals being in the same plane and all of said negative terminals being in another plane parallel thereto, a switch-arm or connector in the plane of said positive terminals adapted to vary the connections therebetween, a second switch-arm in the plane of said negative terminals adapted to correspondingly vary the connections therebetween, and an operating device for simultaneously moving both of said switch arms and thus connecting said work circuit to any of said sources of current,

as set forth.

2. An electric switch comprising a set of positive terminals arranged on the circumference of a circle, a set of negative terminals similarly arranged on the circumference of a circle concentric with the first, all of said positive terminals being in the same plane and all of said negative terminals being in another plane parallel thereto, a shaft turning in the common center of said circles and carrying switch arms or connectors so situated as to form chords to the circumferences of said circles respectivelyand of such length as to bridge any two adjacent'terminais situated on said circumferences, and an operating handle adapted to move said shaft through an arc predetermined by the situation of said terminals, as set forth.

3. In an electric switch having sets of positive and negative terminals mounted in different planes upon one side of the insulating base plate, substantially as described, the combination with switch-arms or connectors adapted to bridge certain of said terminals, of insulating septa movable with said switcharms, a shaft passing through the base plate and carrying said switch-arms and septa, a cam mounted on said shaft, a spring acting on said cam, lugs at the end of said cam whereby said shaft is permitted to come to rest only at certain predetermined positions, and an operating handle for said shaft upon the other sideof such base plate from that upon which the switching apparatus is located, as set forth.

In witness whereofI have hereunto set my hand this 5th day of September, 1893.

AXEL EKSTROM. Witnesses:

J OHN W. GIBBONEY, BENJAMIN B. HULL.

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