US1143175A - Synchronous electrical contact-maker. - Google Patents

Description

F. G. COTTRELL & H. A. BURNS. svwcnaowous ELECTRICAL comm MAKER.

APPLICATION FILED SEPT- 9. 1909. 1,143,175, Patented June 15, 1915.

2 SHEETSSHEET 1.

F. G. COTTRELL & H. A. BURNS. SYNCHRONOUS ELECTRICAL CONTACT MAKER.

APPL1CATION FILED SEPT.911909.

Patented June 15, 1915.

2 SHEETS-SHEET 2- UNITED STATES PATENT OFFICE.

FREDERICK GARDNER COTTRELL, OF BERKELEY, AND HERBERT ALEXANDER-BURNS,

OF OAKLAND, CALIFORNIA, ASSIGNORS "T0 INTERNATIONAL IPRECIIEITATION COM- ?ANY, OF SAN FRANCISCO, CALIFORNIA, A CORPORATION OF CALIFORNIA.

SYNCHRONOUS ELECTRICAL CONTACT-MAKER.

Specification of Letters Patent.

Patented June 15, 1915.

Application filed September 9, 1909. Serial No. 516,950.

To all whom it may concern:

Be it known that we, FREDERICK GARDNER CoT'rRELL and HERBERT ALEXANDER BURNs, citizens of the United States, residing the said COTTRELL at Berkeley, in the county of Alameda and State of California, and the said BURNS at Oakland, Alameda. county, California, have invented certain new and useful Improvements in Synchronous Electrical Contact-Makers, of which the following is a specification.

Our invention relates to electrical contact makers; and it has for its object the provision of a simple and effective apparatus for intermittently connzting systems of conductors with a high potential alternating current circuit at intervals synchronized with the period of the same in such wise as to maintain constant polarity in these conduotors.

To this end our invention consists in the novel construction and arrangement of the apparatus, which we shall hereinafter fully describe, by reference to the accompanying drawings in Which Figure 1 is a perspective view of our contact maker. Fig. 2 is an end View of the same. Fig. 3 is a side View of the same. Fig. 1 is a front View of one of the contactor elements. Fig. 5 is a section of the same. Fig. 6 is a front View of one of the brush holders and brushes. Fig. 7 is a side view of the same. Fig. 8 is a plan of the brush.

The type of contact maker here illustrated is one-designed for a single phase circuit,

and is here shown as operated by a four pole V synchronous motor, but it is to be understood that our invention equally applies to multiphase circuits and other multipolar synchronous motors or other means for driving it.

1 is a base from which rises a frame 2, whose structure includes, in this instance, four equidistant, radiating arms 3, at each end. In these arms are carried four brushbearers 4:, each being made of insulating material sufiiciently rigid and strong, say, for example, miconite, preferably, of tubular section. Each bearer 4 is adjustably fitted to its arms 3, in any suitable manner to enable it to be moved to and adjusted in its proper positionin a radial plane' For example, the ends of each bearer may have embedded in them short bolts 5 which pass through slots 6 in the arms, and receive clamping nuts 7 on their outer ends. Upon each brush-bearer 4:, are mounted two brushes, making eight in the system. These are in corresponding positions and are adjustably mounted. For clearness of descript1on hereafter, these brushes are thus designated, to wit :-A and Bon one bearer; C and D on the bearer diametrically opposite; E and F on the bearer between these on one side, and G and H on the bearer on the opposite side. The details of mounting these brushes are the same in all, and a description of one, say, A, by reference to Figs. 6, 7 and 8 will suflice.

The brush-holder as shown in Figs. 6 and 7 comprises a sectional metallic ring 8 fitted upon the bearer 4. One section of this ring carries a squared projection 9, between the face of which and a channeled cap plate 10, the brush A is clamped by screws 11. The brush A is best slitted as shown at a, in Fig. 8, so that it may slip over and be guided by the screws 11 in its adjustment relatively to its holder. The sections of the holder ring are clamped together by a bolt and thumb nut. at 12.

It will now be seen that there are four ways of changing the brush adjustment. First, by moving the bearers 4 radially. Second, by rotating the brush holders on the bearers. Third, by sliding said holder lengthwise on the bearers. Fourth, by moving the brushes forward or back in their holders. The brush-holders are thus insulated fromone another and from the frame.

Mounted to rotate in the frame 2, is a shaft 13 which lies in the axis from which the arms 3 of the frame radiate. This shaft carriesv the contactors of which there are two, designated as a whole by I and J. As they are alike in construction, a description of one, by reference to Figs. 4 and 5 will answer for both.

The shaft 13 between its end bearings, is covered with an insulating tube 14 of some suitable material, such as hard rubber, micanite, micabestos, etc., which tube fits the shaft snugly. Upon this tube is fitted a hub sleeve 15 one end of which is split and taper-threaded to receive a nut 16 which clamps the sleeve to the tube in a manner which minimizes the weakening of the insulation through injury. The sleeve 15 is formed with or carries a collar 17, to which is screwed a disk 18 of insulating material, such as rubber, or micanite or micabestos or other suitable substance. To the outer portion of this disk 18 is fitted and secured a metallic ring 19, from which extend the diametrically opposite projections 20. The number of these projections depends upon the number of phasesfrom which the current is to be drawn, being two for the phasetype herein illustrated, separated by 180 de-' grees. To the outer end of each projection 20 is removably fitted a rod 21 of small diameter, a good way of fitting said rod being here indicated, namely slipping the rod into a hole drilled radially through the thickened end of the projection, the inner end of the rod being riveted or headed up to prevent it from being thrown out by centrifugal force. The purpose of the insulating disk 18 is to safeguard against electric puncture of the insulating tube 14.

The relation of the contactors to the brushes is such that contactor ll operates electrically with brushes A, C, E and G, and contactor J operates with brushes B, D, F and H. The contactors are relatively disposed to each other in such wise that the rods 21 of one point in a direction 90 degrees from those of the other.

The projections 20 and rods 21 form con ductors extending outwardly from the ring to within sufficient proximity to the brushes to receive current therefrom or deliver current thereto, at the high potentials used with this apparatus, Without, however necessarily making actual contact, (see Fig. 1) the potential being sufficiently high to jump the gap between such conductors and the brushes. This connection is however, only made intermittently, so that each conductor receives current from the brushes only during a portion of each cycle or half cycle of the alternating current and means, hereinafter described, are provided for rotating the contactors in synchronism with the alternating current, and for shifting the phase position of the time of connection with relation to the alternating current, so as to take 0H current at any desired potential, up to the maximum of the alternating supply circuit. The angular adjustment of the brush holders in the brush bearers enexample, by connecting it to the generator for the line itself, or to a synchronous motor driven from the system, the latter type being that herein specifically represented and de scribed.

Secured to the base 1 is a cradle-stand 22 in which is seated concentrically an annular cradle-ring 23 to which the four pole synchronous motor 24 is securely fastened in such wise that its armature shaft 13 is alined with the contactor carrier-shaft 13 to which it is coupled suitably, or said shafts may be integral if desired.

The cradle-stand 22 has a slot 25, through which a handle 26 plays, said handle being fastened to the cradle ring 23, whereby the cradle ring may be turned on its aXis in its seat in the stand. The stand is clamped on the ring to hold it securely, by means of a bolt 27 at its top.

In action, the principal electrical features are as follows :Brushe's A and G are electrically connected together by wire 28 and to one side 29 of the high tension alternating current line. Brushes B and H are electrically connected together by wire 30, and to the other side 31 of the high tension alternating current line. Brushes F and E are electrically connected together by wire 32, and are connected by the wire 33 to one side of the load. Brushes D and C are electrically connected together by wire 34 and to the other side of the load through the ground by wire 35. t

36 indicates the low tension circuit to drive the motor. The brushes are so adjusted. that the rods 21 of contactor I connect electrically brushes A and C at the same moment that the rods 21 of contactor J connect electrically brushes F and H; and similarly, upon rotation of the contactors through an angle of 90 degrees, brushes E and G are connected simultaneously with the the connection of brushes B and D.

As heretofore stated, the synchronous motor 24 is a four-pole type; hence, it revolves once during every two complete cycles of the alternating current by which it is driven. The high tension alternating current circuit source must be synchronized with the low tension circuit driving the motor, the one being most conveniently transformed from the other,'as indicated by the transformer 37.

For convenience of description, beginning when brushes A and C are electrically connected, at which moment brushes F and H are also so connected, let it be assumed that the potential difference between the terminals at brushes A and B is a maximum; then A is connected through I, C and 35 to the ground to one side of the load which is also grounded; while, simultaneously, B is connected through H, J, F and E to the insulated side of the load. By the rotation of the shaft, the circuitis then opened simultaneously at four points in series, namely, at

A, o, H and F. After a half, cycle of the alternating current circuit, at which time the potential difference between terminals A and B is again a maximum, but in an op-" posite sense, the armature of the motor being four-poled, will have rotated one-quarter of its revolution, thus bringing B into,

contact with the grounded side of the load through J, D, C and 35, and at the same time connecting A to the insulated side of the load throu h G, I and E. At the end of the next half cycle the previous connections are restored. This process is repeated every half revolution of the shaft system, and thus with every complete cycle of the alternating current circuit.

Now, in order that the connection of A and B through the contactors to the load may be made at the instant that the potential difference between A and B is a maximunnbr is any desired per cent. of the maximum, the feature, heretofore described, of the bodily adjustment of the motor on its axis by the turning of the cradle ring 23 in its seat is'proyided. By thus bodily turning the motor, the time of contact of the contactors l and J withthe brushes may be so adjusted that the potential difierence at A and B may be impressed upon the load at any of its valueslhe several types of insulation heretofore described are for the satisfactory operation of an apparatus of this nature, where high potential diiierences exist between its parts. Since when the contactors l and J make electrical connection with the brushes A and B, the same potential difference exists between the contactors themselves as between said terminals A and B; and, also, since between each contactor and base frame this same difference of potential is alternately established, the insulation surface of the tube 14 between the contactor-hub-sleeves 15 and between these and the bearing frame must be of sufficient length to limit the electric surface leakage to a negligible amount. Having thus described our invention what -we claim asnew and desire to secure by Letters Patent is 1. An apparatus for maintaining a system of conductors at a high difference of electrical potential by intermittent connection with a source of alternating current at intervals synchronized with the periodof the current, comprising a system of eight brushes in two separated annular series, each series having four equidistant brushes and each brush ofone series being aline with a corresponding brush of the other series in a line parallel with the axis of the system, two adjacent brushes of one annular series being connected th one side of the alternating circuit,'and two adjacent brushes of the other annular series being connected to the other side of the alternatmg current circuit and the other two brushes of each annular series being connected respectively to opposite sides of the system of conductors contact with the brushes of one of the annular series of brushes and the other pair of said conductors being adapted to contact with the brushes of the other annular series of brushes, whereby said conductors by their rotation alternately become connecting links between pairs of said brushes and are sep arated entirely therefrom, thus opening the circuit simultaneously at four points in series. a

2. An, apparatus for maintaining a system of conductors at a high difierence of electrical potential by intermittent connection with a source of alternating current at intervals synchronized with the period or" the current, comprising a shaft driven in synchronism with the alternating current; a system of eight brushes in two separated annular series, each series having four equidistant brushes, and each brush of one series being alined with a corresponding brush of the other series in a line parallel with the axis of the system, two adjacent brushes of one annular series being connected to one side of the alternating circuit, and two adjacent brushes of the other annular series being connected to the other side of the alternating current circuit and the other two brushes of each annular series being connected respectively to opposite sides of the system of conductors to be char ed to high potential; and a series of conducting elements includingd-our' projecting conductors carried by said shaft, said conductors being in separated pairs, insulated from each other, the conductors of each pair being diametrically opposite, and those of one pair being set quartering to those of the other pair, one pair of said conductors being adapted to contact with the brushes of'one of the annular series of brushes and the other pair of said conductors being adapted to contact with the brushes of the other annular series of brushes, whereby said conductors by the rotation of the shaft, alternately become connecting links between airs of said brushes and are separated there rom, thus opening the circuit simultaneously at four points in series.

3. An apparatus for maintaining a sys tern of conductors at a high difference of electrical potential by intermittent connection witha source of alternating current at intervals synchronized with the period of the current, comprising a synchronous .mo-'

tor; a shaft driven by and. in unison with the motor shaft a system of eight bi ushes in two separated annular series, each series having four equidistant'brushes, and each brush of one series being alined with a" corresponding brush of the other series in a line parallel with the axis of the system, two adjacent] brushes of one annular series being connected to one side of the alternating circuit, and two adjacent brushes of the other annular series being connected to the other side of the alternating current circuit and the other two brushes of each annular series being connected respectively to opposite sides of the system of conductors to be charged to high potential; and a series of conducting elements including four projecting conductors carried by said driven shaft, said conductors being in separated pairs, insulated from each other, the conductors of each pair being diametrically opposite, and those of one pair being set quartering to those of the other pair, one pair of said conductors being adapted to contact with the brushes of one of the annular series of brushes and the other pair of said conductors being adapted to contact with the brushes of the other annular series of brushes, whereby said conductors by the rotation of the shaft, alternately become connecting links between pairs of said brushes and are separated therefrom, thus opening the circuit simultaneously at four points in series.

4:. An apparatus for maintaining a system of conductors at ahigh difference. of electrical potential by intermittent connection with a source of alternating current at intervals synchronized with the period of the current, comprising a synchronous motor having a shaft; a cradle-ring in which said motor is secured; a cradle-stand in which the cradle-ring is concentrically mounted and in which it is adapted to be angularly adjusted with respect thereto, whereby said motor is capable of a rotary adjustment about the axis of its own shaft; a shaft driven by and 'in unison with the motor shaft; a system of eight brushes in two separated annular series, each series having fe ur equidistant brushes, and each brush of one series being alined with a corresponding brush of the other series in a line parallel with the axis of the system, said brushes being connected respectively to the alternating current circuit and to the system of conductors to be charged to high potential; and a series of conducting elements including four projecting conductors carried by said driven shaft, said conductors being in separated pairs insulated from each other, the conductors of each pair being diametrically opposite, and those of one pair being set quartering to those of the other pair, one pair of said conductors being inear/t adapted to contact with the brushes of one of the annular series of brushes and the other pair of said conductors being adapted to contact with the brushes of the other annular series of brushes, whereby said conductors by the rotation of the shaft, alternately become connecting links between pairs of said brushes and are separatedtransformer and mechanically connected to said rotary member, to rotate the latter in synchronism with the alternating supply current, and the stator of said machine being shiftable around the axis of rotation of the rotor, to select the 'part of the wave at which connection is established, and thereby variably control the electromotive force impressed on the delivery connections.

6, A rectifying apparatus comprising supply and delivery conductors arranged in circular series, a stepup transformer provided. with alternating current supply connections and having its secondary connected to said supply conductors to impress alternating electromotive force waves thereon, a rotary member havlng conducting means cooperating with said conductors to intermittently establish connection between the supply and delivery conductors, a synchronous motor having its armature electrically connected to the primary of said transformer and mechanically connected to said rotary member to rotate the latter in synchronism with the alternating supply current, the field magnet of said machine being shiftable around the axis of rotation of the armature, to selectthe part of the wave at which connection is established and thereby variably control the electromotive force impressed on the delivery connections.

7. In a rectifier, a rotary member comprising a rotating shaft, air-insulating disk carried by said shaft, a metal ring extending around and secured to, the periphery of said disk, and metallic conductors connected to and extending outwardly from said ring.

8. In a rectifier, a rotary shaft, insulated rotary conductors carriedby said shaft, a frame having guides extending radially with respect to said shaft, insulating supports adjustably mounted in 7. said guides,

and. brushes carried by said insulating supports and adapted to cooperate with said rotary conductors.

9. In an apparatus of the described character, a frame; a shaft mounted in the frame and driven in synchronism with the alternating current; a plurality of conducting elements including projecting conductors, carried by said shaft and insulated therefrom; an annular series of brush bearers'of insulating material carried by and radially adjustable in said frame; a series of brush holders mounted on the bearers and adjustable thereon rotatively; brushes with which the projecting conductors effect electrical connection, said brushes being carried by and adjustable in said holders, and being so placed with respect to the rotating conducting elements that during a portion of each cycle all of said brushes are out of connecting relations with said elements; and electrical connections from the brush holders to the alternating current circuit and to the system of conductors to be charged to high potential.

10. in an apparatus of the described char acter and combination with a synchronous motor having a shaft; a cradlering' in vwhich said motor is secured; a cradle-stand in which the cradle ring is concentrically mounted and is adapted to be angularly adjusted with respect thereto whereby said motor is capable of a rotary adjustment about the axis of its own shaft;

a frame; a shaft mounted in the frame and driven by and in unison with the motor shaft; a plurality of conducting elements including projecting" conductors, carried by said driven shaft and insulated therefrom; an annular series of brush bearers of insulating material carried by and radially adjustable in saidframe; a series of brush holders mounted on the bearers and adjustable thereon rotatively; brushes with which the projecting conductors effect electrical connection, said brushes being carried by and adjustable in said holders; and electrical connections from the brush holders to the alternating current circuit and to the system of conductors to be charged to high potential.

11. In a rectifier a rotary shaft-an insulating tube surrounding said shaft, a hubsleeve fitting on said insulatingtube and having one end portion split and tapered, a member surrounding and engaging said tapered portion of the hub-sleeve, to clamp the hub-sleeve on the insulating tube and circuit controlling conductors carried by said l1ub-sleeve.

In testimony whereof we have signed our names to this specification in the presence of two subscribing witnesses FREDERICK GARDNER QOTTRELL. HERBERT ALEXANDER BURESQ Witnesses: WM. F, Boori-I,

D. B. RICHARDS.

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