US2199991A - Multielement watt-hour meter - Google Patents

Description

y 1 I s. s. GREEN 2.1 3 1 MULTIELEMENT WATT-HOUR METER Filed Jan. 13, 1938 '5 6 Green mm. m7

Patented May 7, 1940 I 2.199.991 I MULTIELEMENT' WATT-HOUR. METER Stanley S. Green, La Fayette, Ind., assignor'to Duncan Electric Manufacturin Fayette, Ind., a. corporation of g Company, La 1 Illinois Application January 13, 1938, Serial No. 184,751

8 Claims.

This invention relates to polyphase meters and more particularly to an interference-proof disc for such meters. Polyphase meters differ from single phase meters by employing two or more complete electromagnetic driving elements, while the usual single phase meter has only one. Polyphase circuits have at least three wires, and at least two meter driving elements are required for theirmeasurement.

For many years theuse of two driving elements hasnecessitated the use of two separate discs one for each element in order to prevent interference between the eddy currents induced in the disc by one element and the magnetic-field of the other. 'I'his'was fully explained in my copending applications Serial No. 33,116,fi1ed July 25, 1935, and Serial No. 124,632, filed February 8, 1937 '(Patent .No. 2,110,417). These applications also describe numerous prior attempts to avoid the expense of a'disc for each driving element, explain wherein they had failed to satisfactorily solve the problem, and disclose a satisfactory solution. The present invention utilizes the principles of the solution previously described though the structure is of a somewhat different form.

The general. principle 'of' the solution of the problem is to provide a rigidunitary disc made upof laminations thoroughly insulated from one another except at theircenter portions and each lamination including radially extending slots staggered with respect to the slots 017 other laminations and dividing the disc as a whole into I a plurality of overlapping conductive sections substantially isolated from one another to the extent that eddy currents induced in one section will not flow through the other sections. The

driving elements are so positioned, and the sections so proportioned, that no section is materially influenced "by more than one driving element at a time.

In the prior: applications these principles were satisfactorily embodied in a disc in which the conductive laminations were rigidly secured together throughout their area by an insulating binding material. According to. the present invention the insulating material need not be adhesive, as the laminations are held together by me- I chanical means such as rivets or a binding thread positioned at the periphery of the disc preferably slightly beyond. the various magnet poles so as to make countersinking of the securing means unnecessary. Countersinking can be resorted to, however, if thespace and the torque requirements as do not permit positioning, the securing means as stated. The laminations are filmly secured together at their centers by the hub.

Additional objects will be apparent from the: following description and from the; drawing, in which:

Fig. 1 is a diagrammatic illustra embodying this invention. Fig. 2 is a diagrammatic illustration indicating the structure and assembly-of oneform of slotted and laminated disc constructed in accordance with this invention.

Fig. 3 is an enlarged fragmentary; sectional view of the disc shown in Figs. 2 and '4, being taken approximately on the line 3-3 of Fig. 4.

Fig.4 is a plan viewof the disc showing also the arrangement of magnet poles on the disc and their positioning within the line. of rivets.

Fig. 5 is a fragmentary plan'viewof a modified form of discin which the flaminations are held together by a binding cord instead of by rivets, and

Fig. 6 is an enlarged fra the disc shown in Fig. 5'.

Although this invention may take a variety of forms, only two have been chosen for illustration. In both forms the invention is concerned with a slotted and; laminated disc [I suitable for use in multielement' meters such as polyphase meters and mounted on a rotatable shaft 12 which drives a meter register, not shown. As described in my copending application Serial'No. 124,632, (Patent No. 2,110,417) such a disc prevents interference within the disc between driving elements A'and B, each of which sets up eddy currents in the disc. The eddy currents from one driving element would be affected bythose from another if they were not restricted by the slots to the zone in which they originate. The laminations in the'disc permit the formation of a disc which will rotate smoothly in spite of the slots. But for thelaminations and the attendant staggering of tion of a meter gmentaryedge view of jerky, and the meter would be completely inoperative at light loads since such a disc would have a strong tendency to stop with a slot under a driving element.

Each of the driving elements A and B includes a potential magnet having a pole 13 adjacent one face of the disc and a current magnet having spaced poles 14 adjacent the other face of the disc. The illustration of these magnets is entirely diagrammatic. A preferred form of driving unit including a potential'magnet and a current magnet in one structure is illustrated in my copending application Serial No. 48,713 (Patent No.

the slots the movement of the disc would be very 2,167,649, issued August 1, 1939). In order to obtain adequate damping torque for such a disc when it is driven by two driving elementsA and B, two permanent damping magnets l6 are provided, each having its two poles adjacent one face of the disc, and an armature l1 adjacent the other face of the disc so as to produce two opposed concentrated magnetic fields in close proximity to one another. The opposed adjacent fields have much stronger damping effect than would be the sum of the fields alone especially with the illustrated slotted disc. nets producing two such pairs of opposed adjacent field can be placed as indicated in Fig. 4 midway between the driving elements. With an even number of driving elements it is rather desirable to have an uneven number of slots 19 in each lamination so that slots will not be centered under pole 13A and under pole l3B at the same 1 time.

It is desirable to have themagnetic gaps such as the gap between the pole l3 and the pole l4 of one driving element as small as is commercially practicable, since this will'produce the maximum torque, other factors being the same. In order for the disc to operate in such a small gap it is vital not only that it be quite thin, but also that its laminations be dependably secured together. In my copending application Serial No. 124,632 (Patent No. 2,110,417), this vital feature was accomplished by securing the laminations together with an insulating binding layer. A

disc produced in that manner is very satisfactory but the present invention contemplates other forms of disc which will be satisfactory without adhesive layers between the laminations. When adhesive layers are used it has so far been considered advisable to use a non-flowing spacer member such as a thin sheet of paper to make 1 certain that the laminations are not pressed into contact with one another by the pressure which is used in securing them to adhere together. When no adhesive is used such pressure is not necessary, and some-simplification of manufacture may therefore be possible by simply spraying a coat of insulating paint on the laminations or possibly forming a coat of insulating oxide on them. In other words, the present invention for mechanically securing the laminations together may be advantageous in some instances in simplification of manufacture, but in any event it comprises a useful alternative for the adhered type of laminated disc already found satisfactory. I

In both forms of the present invention the disc may include outer laminations 2! and a center lamination 23. Of course, as few as two or as many as five laminations could be used. but three is preferred in the present form of the invention.

(Patent No. 2,110,417) previously mentioned,

the torque is reduced as the number of slots per lamination is increased. Furthermore, it is reduced, as to a disc of a given total thickness, as the amount of non-conductive separation between the laminations is increased.

The two mag By using three laminations, having seven slots each, a disc is provided in which the reduction of torque by the slots is not particularly high and in which the individual. laminations are sufficiently strong to be dependably secured together by the mechanical means to be described and in which the thickness of non-conductive spacing material may be kept at a minimum.

The three laminations must be insulated from one another except at their center portions (the portions inside the ends of the slots). The insulation preferably comprises a thin coating between each pair of laminations. Such a coating may be applied to or formed on any of the inner faces of the laminations, that is, the inner face of either or both of the outer laminations 2i and either face of the central lamination 23. Such a coating maybe an extremely thin layer of insulating paint sprayed on the lamination or a thin layer of oxide formed on the lamination. Before, the coating isapplied or formed,jany

burrs on the laminations which might result fromstamping them out, for example, should be: flattened as with a flattening die in a press. Un-

der such circumstances the insulation may be ex, tremely thin, its thickness inFig. 2 being some-' what exaggerated for the sake of clarity. With:

such thin separating coatings and with only three laminations so that there are only two separatingcoatings it is evident that the disc is substantially all formed of conductive material. This is desirable from-- the standpoint of obtaining; maximum torque and makesit possible to obtain: satisfactory torque even though seven slots are used in each lamination. It may be preferred to use this many slotsper lamination when only. three laminations are used since from twenty-one.

to twenty-five-slots hasbeen believed to be the;

most satisfactory number in balancing thesomewhat conflicting requirements, of torque. and

smoothness. Fifteen slots or five slots per lamination can be used, however, with atleast fairly satisfactory results; and in some instanceseven fewer could be used. Fifteen slots have recently been found to be entirely satisfactoryin somewhat similar discs when the discs are made under conditions which result in extreme uniformity. I

The laminations maybe secured together by rivets 26, one of which should be positionedat each peripheral corner of the sections as seen in. Fig. 4. Of course, theremay be others along theperiphery, and some could be positioned along each exposed slot radially inward fromthe magnet poles. It is believed that thoseshown are enough, however. More than necessary are undesirable because they reduce the torque, be-

ing insulated as described below.

It is highly desirable that these rivets should not electrically connect the laminations since.

even a small degree of electrical connection at the. outer part of the disc may be very detrimental as to the interference eliminating qualities of the disc. The rivets should therefore be made of insulating material or adequately coated with an insulating enamel, preferably a flexible enamel such as that commonly used for enam eled wire. Although even such flexible enamel would ordinarily be split at the inserted end 21 of the rivet when it is upset, the remainder of the enamel will remain intact, thusinsulating the' rivet from the other two laminations, and in fact, the insulation may be omitted from the end to be upset. The result is that no electrical corinection will be'formed between the laminations.

set

When the thickness or the laminations will permlt, it is desirable to countersink the rivets 26- in the 'outer'laminations as seen in In case the countersinking may not be perfect or'if' countersinking is not resorted to, the rivets should be positioned radially beyond all of the magnetiepole pieces as seen in Fi-g. 4- so that there ben'o' danger of any' projecting rivetportionstrikingone of these pole pieces and stop:- pi'ng'the disc. With the rivets thus located it is not necessary tomake the magnet gaps any widerin order to allow more to-ierancefor the rivetsn- OI course, ifyspace requirements will not permit the slightly oversize disc it is merely necessary to make certain that the countersinking 0f the rivetsis complete, and they may then run through the magnet gaps.

To avoid the necessity of insulating rivets the laminations may be held together by an insulating thread 3|, as seen in Figs. 5 and 6, this thread being wrapped through small notches 32 formed in all three laminations and alined during assembly. The ends of .the thread may be tied or glued together in one of the notches and the entire thread maybe varnished after application to help hold it in place and to give it durability and moisture resistance.

Although it is believed that either of the peripheral securing means described will be sufficient to hold the laminations together, especially with the aid of the conventional hub, it may be preferred to use a hub having an enlarged flange 36 extending approximately to theinner ends of the slots 19 and a washer i l on the opposite side of. the disc. The stem of the hub will of course be inserted through the central hole in the finished disc and through the washer 31, after which it will be upset or swedged to secure it in place. The hubbed disc may then be secured to the shaft in the conventional manner.

The center lamination 23 may be provided with projecting teeth 39 extending beyond the other laminations. Such teeth have been commonly provided on meter discs in the past for the purpose of testing and adjusting the meter by stroboscopic methods. Of course, such teeth could be provided 'on all three laminations, but their provision on the center lamination only is preferred so as to avoid the necessity for extremely accurate alinement of the'teeth. If desired, the center lamination could be made thicker than the others so as to give these stroboscopic teeth greater strength. From the foregoing it is evident that two forms of. the invention have been illustrated, each of which provides a laminated interference-proof disc capable of providing high torque smoothly and having the laminations adequately insulated and dependably secured together.

The disclosures of'this application are illustrativeand the invention is not to be limited by them. In fact, if modifications or improvements are not at once obvious, they may-be devised in the course of time-to make additional use of the broad ideas taught and covered by this application. The claims are intended to point out novel features and not to limit the invention except as may be required by prior 'art.

I claim:

1. A Watt-hour meter mechanism comprising a disc rotatably mounted about a given axis, a plurality of electromagnetic driving elements having poles adjacent the disc, and damping magnet means having poles adjacent the disc; the disc having a plurality of conducting sections electrically separatedfrom eachother sufiici'ently toconfine thecurrents induced therein by the driving elements to substantially the individual segments, having an areaand shape with reference to the discfsuch that when under the magnetic influence "of'one driving element they are removed from any substantial. magnetic in-- fiuence of another driving element, spaced out in staggered and overlappingrelation in their assembly in the-disc, separated from one another by a layer of insulating material and being firmly-- secured together in the vicinity'of' the axis by the-hub structure and adjacent the periphery by mechanical securing means positioned radially beyond the poles to eliminate danger of the securing means striking thepoles.

2. A watt-hour meter mechanism including a plurality of electromagnetic driving elements and a rotatably mounted disc driven thereby and hav ing a plurality of angularly staggered slotted conducting laminations substantially insulated from one another as to currents induced by the driving elements by thin, substantially non-flowable, insulating coatings and secured together by mechanical securing means near the periphery of the disc engaging the outer laminations and extending through. the other laminations without electrically connecting the laminations.

3. A watt-hour meter mechanism including a plurality of electromagnetic driving elements and a rotatably mounted disc driven thereby and having a plurality of angularly staggered slotted conducting laminations substantially insulated from one another as to currents induced by the driving elements by thin, substantially non-flowable, insulating coatings and secured together by rivets near the periphery of the disc and extending substantially through the disc without electrically connecting the laminations and having heads countersunk in the outer laminations.

4. A watt-hour meter'mechanism including a plurality of electromagnetic driving elements with a rotatably mounted disc driven thereby and having a plurality of angularly staggered slotted conducting laminations substantially insulated from one another --as to currents induced by the driving elements by thin, substantially non-flowable, insulating coatings and secured together by rivets extending substantially through the disc without electrically connecting the laminations and positioned radially beyond the portions of the driving elements close to the faces of the disc.

5. A watt-hour meter mechanism including a plurality of electromagnetic driving elements and. a rotatably mounted disc driven thereby and having a plurality of angularly staggered slotted conducting laminations substantially insulated from one another as to currents induced by the driving elements by thin, substantially non-flowable, insulating coatings and secured together by metallic rivets separated from all but one of the laminations by an insulating enamel.

6..A watt-hour meter mechanism including a plurality of electromagnetic driving elements and a rotatably mounted disc driven thereby and having a plurality of slotted conducting laminations substantially insulated from one another as to,

currents induced by the driving elements by thin,

ing a plurality of slotted conducting laminations substantiallyvinsulated from one another as to currents induced by the driving elements by thin, substantially non-fiowable, insulating coatings and secured together by mechanical securing means near the periphery of the disc engaging and extending between the outer laminations without electrically connecting the laminations, one of the laminations having stroboscopic teeth formed thereon projecting beyond the other laminations.

8. A watt-hour meter mechanism including a plurality of electromagnetic driving elements :and arotatably mounted disc driven thereby, said disc consisting of a plurality of but .not over three I Q conducting laminations, each having at least five slots dividing up said laminations into substanby the hub and by mechanical means near-the m periphery of the disc whereby reasonably good rigidity is obtained.

STANLEY sqqnnENl

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