US1729402A

US1729402A - Inghouse electric

Info

Publication number: US1729402A
Authority: US
Publication date: 1929-09-24
Anticipated expiration: 1946-09-24

Description

24, 1929-V A. R."RUTTER 1,729,402

ALTERNATING CUIIRENll MOTOR METER Filed Aug. 2Q, 1924 WITNESSES: INVENTOR MM A/yy/e /Pas5e// ADI/fer? BY t ZMM ' ATTORNEY Patented Sept. 24, 1929 UNITED STATES ARGYLE IR. R'UTTER, 0F EAST PITTSBURGH, PENNSYLVANIA, ASSIGNOR TO WEST- PATENT OFFICE INGHOUSE ELECTRIC & MANUFACTURING COMPANY, A CORPORATION 0F PENN- SYLVANIA ALTERNATING-CURRENT MOTOR METER Application filed August 20, 1924. Serial No. 733,049.

My invention relates to alternating-current apparatus and particularly to motor meters of the induction type.

One object of my invention is to provide a wattmeter, relay or watthour meter of the induction type that shall be exceptionally accurate over a Wide range of current, volt age and frequency.

Another object of my invention is to provide an improved method of forming the laminated core member of an instrument of the induction type.

In the accompanying drawing Figure 1 is a view of an alternating-current motor of the induction type to which my invention is applicable; and

Fig. 2 is a plan View of a. modied form of lamination.

Referring to Fig. l. a motor l for a wattmeter or relay comprises a magnetizable core member 2, energizing means therefor in the ferm of series and shuntv windings 3 and 4,

andma pivoted armature 5 cooperating with said core member.

The core member 2 is constructed of ilat or plane sheets or laminations having an outer perimetral portion or closed-magnetic circuit in the form of a. closed loop. The elongated shunt pole portion on which the voltagewinding 3 is disposed. extends inwardly from the loop and is provided with :tree-end extensions l5 which are paired in slightly spaced parallel side-edge relation to portions 14 supported at, and extending inwardly from, the loop through the intermediary of the transverse portion having the dimension 9.

lVhen the series and shunt windings 3 and 4 are `energized, alternati/ng magnetic fluxes traverse the edge of the armature 5 and produce a torque thereon. the magnitude and direction of which depend upon the magnitude and direction of the currents in the windings and upon the character and location of the core member 2. The instrument l may be an integrating or indicating wattmeter or a relay, depending upon the elements controlled by the armature 5. As the specific character of these elements is not essential to my invention and such elements are well known, they are not shown.

Since the voltage and frequency supplied to a watthour meter in service are maintained substantially constant, these characteristics have always been ignored and the instruments built to read correctly for variations of current and power factor only. The eect of increasing` the voltage applied to the shunt winding' 4 is to cause increased damping of the armature 5 and, therefore, the instrument to read low as-the voltage is increased and the power kept constant. It is possible,

however, to so modify the relation of the magy netic paths of the flux produced by the shunt winding traversing the disc that an increased torque is obtained that compensates for the normally increased damping effect.

Theoretically, the induction-type Wattmeter is independent of variationsI of frequency at unity power factor but actually the increased reactance of the Windingscauses a diminished torque when the frequency is in creased and the power kept constant. It is possible to compensate for this also, by modif tying the ma gnetic paths of the flux produced by the shunt winding. `The compensation for voltage and frequency each slightly affects the other adjustment but it. is possible t0 make a change that is a compromise so that the instrument will be substantially accurate for variations in both .voltage and frequency. As shown in Fig. l, the ux produced by the shunt winding 4 has three dlstinct paths v y 6, 7 and 8. The flux of the path 6 does not traverse the armature 5 and, therefore, does not adect the operation ot the instrument. The fluxes of the paths 7 and 8 both traverse the armature 5 and, therefore, the fluxes following these aths exert a torque on said armature. hanging the dimension 9 of the core lamnations varies the relative reluctance of the three paths 6, 7 and 8 `and this change varies the voltage characteristic,

4or lux variation caused by voltage varia.-

tions, of the instrument so that either a flat, a drooping or a rising characteristic ma be obtained. Changing the dimension 10o the core laminations also varies the relative reluctance of the paths 7 and 8- and I have found that this change varies the frequency characteristic, or flux variation caused by frequency variations, of the meter so that this characteristic maybe made either fiat, drooping or rising, as desired'. Changing either of the

dimensions

9 and 10 changes both the voltage and frequency characteristics to some extent but, since each affects one characteristie more than the other, it is ossible to compromise upon the changes so trat the desired voltage and frequency characteristics may both be obtained.

In Fig. 2 is shown a modified form of a one-piece core lamination suitable for a watthour meter in which the accuracy is not affected by changes in voltage and frequency. The' lamination 11 is a punching of sheet steel. In order to obtain these laminat-ions in large quantities and of accurate dimensions they are punched from sheet metal With accurate dies. These dies are expensive and, consequently, itl is not possible, from a practical standpoint,I to alter any of the dimensions of the punching after the dies have been made, on account of the expense involved.

` In order to practice my invention, the lamination 11 is punched out in approximately the desired form with an excess of material in the pole pieces 'and yokes. It is not practicable to obtain a lamination having exactly the desired characteristics because of the intricate .form of the punching and the many factors'involved. Accordingly, the punchings 11 aresubsequently perforated at 12 and 13 to modify the voltage and frequency characterstics thereof, as desired.

While the perforations 13 are indicated as approximately circular and as extending through each of the portions 14 and l5, they are so provided merely as a matter of manufacturing facility and to avoid the removal of an excess of material from the portions 15, the purpose being to con strict the portions 15. In other Words, While the extensions 15 may be locally const-ricted or proportioned in any desired manner, it has been found to bc a matter of manufacturimer facility and structural effectiveness to constrict the portion 15 by the use of a tool of symmetrical cross-sectional contour that is driven normal to the plane of the core along a center point or line preferably in the space between the

portiops

14 and 15, it being immaterial that a portion of the extension 14 is thereby also removed.

It is a simple matter to determine experimentally the 'dimensions of the perforations l2 and 13 that will provide' flat frequency and voltage characteristics by testing instruments in Whleh various sizes of perforations have been formed.

For example, increasing the size of the perforations 12 tends to flatten the normally drooping voltage characteristic curve of the meter, and increasing the size of the perforations 13 corrects the normally. drooping frequency characteristic curve. As above indicated, these perforations may be independently progressively increased in size until a fiat or rising frequency or voltage characteristic curve is obtained. Actually, however, alteration in the size of either the perforations 12 or that of the erforations 13 affects both the voltage and requency characteristics. It is necessary, therefore, to so proportion the size of the perforations that a compromise is effected whereby the voltage and frequency characteristic curves approach a desired straight-line condition and are substantially fiat.

lVhen the sizes of the perforations 12 andl 13 have once been determined for a givenlamination, the proper perforation of additional laminations may readily be accomplished.

Another advantage of this method of forming the 'laminations is that the projecting portions 414 and 15 of the laminations are mechanically stronger when -they are perforated, as at 12 and 13, instead of the

portions

14 and 15 being reduced in width sufficiently to provide the desired characteristics.

The ux of the path 7 is instantaneously bidirectional through the armature 5 and the flux Yof the path 8 is instantaneously unidirectional through thc armature. Also, the local constrictions in the portions adjacent to the

dimensions

9 and 10, caused by the perforations or

recesses

12 and 13, respectively, so roportion these portions that the relative re uctances of the paths 7 and 8, and consequently ythe ux distribution thereof, are such as will approximately avoid error in the registration of the instrument caused by frequency and voltage variation between predetermined limits. In other words, the ratio ofthe values of the instantaneously unidirectional iux of the path 8 to the values of the utilized to provide such 4instruments with either drooping or rising voltage and frcquency characteristlcs, as Well as a fiat characteristic. Accordingly, I do not wish to be limited to the precise form of my invention shown and described, as this description is for the purpose of exemplilication only.

I claim as my invention:

l. In an electric motor meter, the combination with an armature and energizing means, of a core co-operating between the energizing means and the armature having pole portions and providingr an armature gap and paths for alternating fluxes one of which is instantaneously unidirectional through the armature and another of which is instantaneously bidirectional through the a.rmature,the reluctance of said paths being such as to cause such relative tiux distribution in said paths as will substantially avoid error inA registration caused by frequency and voltage variation between predetermined limits.

2. In an electric motor meter, the combination with an armature and energizing means, ot a. core co-operating between the energizing means and the armature having pole portions providing an armature gap and paths for alternating fluxes one of which is instantaneously. unidirectional through the armature and another of which is instantaneously bidirectional through the armature, portions of said core being proportioned to increase the ratio of unidirectional flux values to bidirectional flux values between predetermined limits of flux tfhange and to diminish that ratio for variations beyond said limits.

3. In an electric motor meter, the combination with an armature and energizing means, ot a core cooperating between the energizing means and the armature having pole portions providing an armature gap and paths for alternating fluxes one of which is instantaneously unidirectional through tlie armature and another of which is instantaneously bidirectional through the armature, the core having locally constricted portions to cause such relative flux distribution in said paths as will substantially avoid error in registration caused by frequency and voltage variations between predetermined limits. 4

4. In an electric motor meterkthe combination with an arn'iaturc and energizing means, ot' a core co-operating between the energizing means and the armature having pole portions providing an armature gap and paths for alternating fluxes one of which is instantaneously unidirectional through the armature and another of which is instantaneously bidirectional through the armature, the core having locally constricted portions to increase the ratio of unidirectional flux values to bidirectional flux values between predetermined limits of linx change and to diminish that ratio for variations beyond said limits.

5. In an electric motor meter, the combination witlran armature and energizing moans, of an alternating-linx field-magnet core cooperating between the energizing means and the armature comprising a closed loop, a pole portionprojectiiiga A tions projecting 'inw 'rd1y,iromthe""loop :to

positions adjacentto opposite sides-'ofi .said

pole portion 'and pole* portions projecting from the loop andextending subStanti-.ily parallel to said first pole portion, e'aclfinclu ing-"a1 local portion' of I con'st-'rieted' oros predetermined manner, v -I G. In an electric'xnotor meter, the combination. with an armatureffandenergizing; means, of-an alternatingflujr-plane lamina-ted eld. magnet core cti-operating between the energizing means and the armature "comprising a 'closed loop, 'an elongated pole portion projecting inwardly from said loop, a pair of portions extending from the free endof said pole portion, portions projecting transversely of said pole portions and inwardly from the loop to positions'adjaccnt opposite sides of the pole portion, and extensions of said transverse portions extending vfrom positions ad] a'- ccnt to the-inner ends thereof each in slightlyspaced parallel side-edge relation to one of said pole-portion extensions, said transverse local portion constricted incross-sectional areav to control the etiect of variations of the core tlux, and portions projecting transversely-ot said pole portion and'inwardly from the loop, each having an eften'slion-paired.with one of said pole-portion extensions in' slightlyspaced parallel side-edge relation thereto.

8. In an elect-ric motor meter, the combinationWi th an armatureandenergi zi n g means, of an alternating-tluxiplanelamina-ted fieldmagnet core co-operating between the. energizing means and the armature comprising a.

closed loop, an elongated pole portion projecting inwardly from said loop, a pair or portions extending from the free end of said pole portion, each having a local'v portion constricted in cross-sectionalrarea to control the ctlcct of variations of the'core flux, portions projecting transversely 'of said pole portionV and inwardly from the loop to positions adj acent opposite sides of the-pole portion and each having a local portion .of lconstricted cross-sectional area. to control theetfect of variations of the core flux, and extensions of said transverse portions extending from positions adjacent to the inner ends thereof each.

in slightly-spaced parallel side-edge relation to one of said pole-portion extensions.

A ing la closed loop, an elongated lpole portion having an extension longitudinally of' said thereto, one edge of eac-hief said A9.A In ari-electric motor meter, the combination with an armature and energizing means, Vof an alternating-ilux plane laminated tield-I magnet core cao-operating between'the ener#- gizing means and the armatureeomprising a closed loop, an elongated pole portion projecting inwardly from said loop having longitudinal freeend extensions, and portions pro.-

jecting transversely of said pole portion and' inwardly from the loop, eael` having an extension longitudinally of lsaid. pole portion pairedlwith one of said first extensions slightly-spaced parallel side-edge relation pairs haying a recessed portion. Y I

10. In an electric motor meter, the Comhination with an armature and energizing means, of an alternating-linx plane laminated field-magnet core lcti-operating between the energizing means and thearmature comprisprojecting inwardly from said loop having longitudinal free-end extensions, and pol.- tions projectingtransversely of said pole portion and inwardly from the loop, -eaeh pole portion paired with one of said first extensions in slightly-spaced parallel sideedge relation thereto, each of -said edges having normal to the plane of the core 'a recessed portion the outline of which in said plane is 'Y y disposed symmetrically about a center point about which the outline of the next adjacent recessed portion'is symmetrically disposed.

In testimony whereof, I have hereunto subscribed my naine this 18th day of August, 1924.

ARGYLE R. BUTTER.