US698666A - Alternating-current meter. - Google Patents

Description

No. 698,666. Patented Apr. 29, I902. T. DUNCAN.

ALTERNATING CURRENT METER.

(Application filed Nov. 4, 1899. Renewed Dec. 16, 1901.) (No Model.) 2 Sheets-Sheet I.

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No. 698,666. Patented Apr. 29, I902.

T., DUNCAN. ALTERNATENG CURRENT METER. [Application filed Now 4, 1899. Renewed Dec. 16, 1901.) (No Model.) 2 Sheets-Sheet 2.

E'EEEEH NITED STATES THOMAS DUNCAN, OF CHICAGO, ILLINOIS, ASSIGNOR TO THE SIEMENS & IIALSKE ELECTRIC COMPANY OF AMERICA, OF CHICAGO, ILLINOIS, A

CORPORATION OF ILLINOIS.

ALTERNATlNG-CURRENT METER.

SPECIFICATION forming part of Letters Patent No. 698,666, dated April 29, 1902.

Application filed November 4, 1899. Renewed December 16, 1901. Serial No. 86,056. (No model.)

To aZZ whom it may concern: 7

Be it known that I, THOMAS DUNCAN, a citizen of the United States, residing at Chicago, in the county of Cook and State of Illinois, have invented a certain new and useful Improvement in Alternating Current Meters, (Case No. 308,) of which the following is a full, clear, concise, and exact description, reference being had to the accompanying drawings,-forming a part of this specification.

My invention relates to alternating-current motor-meters, and particularly to that kind of motor-meter having a field-producing winding upon its armature that will measure the so-called wattless component of current in an alternating-current system of distribution such as is set forth, for example, in my application, Serial No. 735,807, filed of even date herewith.

The object of my invention is to provide an improved means for adjusting the phase of the field due to the shunt-winding. Heretofore in applications, Serial Nos. 730,847, 730,848, 730,8t9, filed September 18, 1899, and Serial No. 733,290, filed October 11, 1899, I have shown and described a method of and means for measuring the wattless component of alternating current by means of motor-meters, the type of meter shown in the said application being of the inductionmotor-meter type. Generally speaking, my present invention is a modification of the general class of motor-meters shown in the said applications, which is designed to accomplish the same general result and specifically is an improvement upon the invention disclosed in the first aforesaid copending application. In the present invention I employ a meter whose armature is provided with one of the field-producing windings and associate a phase-modifying winding in cooperative relation with the armature-winding. In practicing my invention I employ an armature having a field-winding divided into coils which are connected withacommutatorsomewhat analogous to the armature of a directeurrentmotor.

As is well known to those skilled in the art, the current of an alternating-current system may be divided into, two components, one of which isin phase with the electromotive force of the circuit,'while the other has a lag of ninetydegrees. This lattercomponentconstitutes the magnetizing or wattless component of the output of alternating-current central stations, and I am enabled to measure this wattless component by means of my improved com mutated motor-meter.

Prior to the invention of my said'copending applications the methods and means for measuring the wattless component were likely to be inaccurate and were tedious and awkward. The usual method practiced was to make a comparison of the indicated voltamperes obtained by multiplying the reading of the indicating-voltmeter by the reading of the indicating ampere-meter-with the out= put in watts obtained from an integrating wattmeter. The latter instrument gives the average watts during a. certain interval of time, and the volts and amperes are obtained by successive readings of the switchboard indicatinginstruments. As an illustration of what may happen in obtaining results by this crude method we may assume that the watts in a circuit as obtained through successive readings of an integrating wattmeter are five thousand, the average voltage being one thousand and the average current a little less than five amperes. The lag in the circuit would then be slight and the indications of the integrating wattmeter would give Very nearly the apparent watts in the circuit.

Owing to the temporary fluctuations in a circuit due to motors, the current indicated may for an instant be four amperes, which unusual fluctuation would not be apparent in the readings of the integrating wattmeter to any extent. There would then apparently be a power factor of more than one hundred per cent., the power factor representing the ratio of the true watts to the apparent watts, the apparent watts being obtained by the product of the indications of the switchboard-ammoter and switchboardvoltmeter, Improved means, therefore, for measuring accurately and instantly the lagging component of the current are important,especially Where alterwhat is called adjusting for minimum curcated by instruments of the same type and comparatively calibrated accurate results are not obtained. For example, if the volt-amperes or apparent watts exceed the true watts by only one per cent. it means that there is upon the line a wattless or magnetizing current with a strength fully fourteen per cent. of that of the energy-current. If the excess is two per cent., the magnetizing-current is twenty per cent. as great as the energy-currentthat is to say, if the true watts are one hundred and the apparent watts one hundred and one the lagging component, which is found by taking the square root of the difference of the squares of the true and apparent watts, would be fourteen per cent., and

,if the true-watts are one hundred and the.ap

parent watts one hundred and two the lagging component will be twenty. From this illustration it will be apparent that very great and disturbing variations of the wattless output afiect but slightly the indicated volt-amneres.

An attempt to secure approximate compensation for the lagging component always existing with induction-motors is sometimes made by the use of synchronous motors for large loads. By means of the synchronous motors aleading current may be produced to balance the lagging component due to the in-v duction-motors. The amount of leading or lagging current which the synchronous motors will induce into the system depends upon the excitation of their fields, and the setting of the field-rheostats which determine this excitation is made by the crude process of rent, which will reduce the dilference between the apparent and true watts in the circuit to a minimum. The current,.however, is subject to fluctuations often as high as seventy-five per cent., and since a variation of onlytwo per cent. in the minimum means the introduction of a twenty-per-cent. magnetizing-current it is readily seen that this method of attempted regulation is not satisfactory.

In running alternating-current generators in multiple itis well'known that the division of the load cannot be adjusted by varying the field excitation of any one or more than one of them; nor can the load of one machine be measured by ampere-meters. Any variation of the field excitation only causes a change of the voltage, and a consequent cross magnetizing-current from one machine to the other demagnetizing one and building up the ceases field of the other to an equality. This cross magnetizingcurrent should for minimum heat and maximum efficiency be kept as small as possible. 7

- By means of my invention I am enabled to employ a commutator motor-meter having a phase-modifying winding in cooperative relation with a meter-winding that is adapted to measure this cross magnetizing-currentaccu rately and readily and to measure and indicate or integrate the lagging or wattless component of an alternating-current system.

Generally speaking, com mutated alternating-current motor-meters heretofore devised are provided with shunt or pressure coils forming armatures which are capable of rotation and which receive current that is approximately in phase with the impressed electromotiveforce. This currenttraversingthe armature by a commutator sets up a mag netic field that is proportional to the impressed pressure and operating in conjunction with another field produced by a series winding traversed by the main current produces a resultant torque which is proportionate to the real watts, and assuming that the electromotive force is maintained constant the torque will vary as the cosine of the angle between the electromotive force and current or the magnetism ofthe shunt and series windings. In practicing my present invention 1 preferably employ a commutated meter whose armature is composed of windings that are adapted to be connected in bridge of supply-mains by means of a commutator and brushes, as it is undesirable to include the armature-winding in circuit, so as to receive the main current or a fraction thereof as it is conveyed to the translating devices. I associate a phase-modifyingwindingin cooperative relation with the armature. I thus provide means by which the torque of the commutated meter will be maximum when the angle of lag between the electromotive force and the current is ninety degrees. In a commutated wattmeter the torque will be zero when the angle of lag is ninety degrees. Thus in a commutated wattmeter the greatest turning effort is exertedwhen there is no difference in phase between the current and electromotive force, and no turning effort is exerted when there is a difference of ninety degrees in phase between the current and electromotive force, as the current is then wattless, whereas in the meter of my invention the torque is greatest when the current is wattless and zero when there is no lag.

Where induction-meters are employed to measure the wattless energy, the magnetism which represents the electromotive force is maintained in phase with the electromotive force, while in the preferred form of commutated type of motor-meter that I employ the pressure magnetism must be maintained in quadrature with the electromotive force, so that when the current in the work circuit lags ninety degrees it will be in phase with the uring wattless components the fields due to the series and shunt windings should be in phase when the angle of lag is ninety degrees and should vary the torque upon variation in the angle of lag, these fields being in quadrature when there is no lag in the'circuit. I will explain my,inveution more particularly by reference to the following drawings,

illustrating the preferred embodiment thereof, in which- Figure l is a diagrammatic view showing a meter and its circuit connections in accordance with my invention. Fig. 2 is a vector diagram showing the relations in the circuits of a system embodying the invention. Fig. 3 shows a modified form of meter with its connections. Fig. 4 shows another modified form of meter with its connections.

Likeparts are indicated by similar letters of reference in the different views.

A source of alternating current 1 supplies current to translating devices 2. Au armature 3, composed of coils of fine wire, is mounted upon the rotating spindle 4, series coils 5 5 being included in series with one of the main conductors extending from the source of alternating current to the translating devices. In Figs. 1 and 4 the coils 5 5 are in series with each other. In Fig. 3 they are in multiple. These series coils are located upon opposite sides of the spindle 4, the armature projecting within the interior of the said coils. Said series winding is thus included in series with the translating devices and sets up a magnetic field that is proportional to the current strength. The coils of the armature 3 are connected with the segments of the commutator 6 in a usual way, the commutator-brushes 7 serving to include the armature in a bridge between the main leads extending from the generator. In order to have the meter accurately measure the wattless or magnetizing components in alternating-current power-circuits, I provide means whereby a torque varying as the sine of the angle of lag is created. This I accomplish in commutated meters by bringing the fields due to the series and shunt windings in phase when the current in the Workcircuit lags ninety degrees, thereby to produce the maximum torque and bring about a variation of the phase difference between these fields when the current ceases to lag ninety degrees. I

In the particular embodiment'of the invention shown the pressure-field should be maintained in quadrature with the line-pressure,

the winding 9.

ance 12.

so that the torque will vary as the sine of the angle of lag of the currentgthrough the translating devices and be zero when the current and pressure are in phase when there is no lag in the work-circuit. I cause the revoluble armature to create a magnetic field that is approximatelyin quadrature with the pressure by passing current to the armature through an impedance-winding 8, which nearly ninety degrees, and using my improved supplemental-means for bringing the pressure-field into exact quadrature with the pressure, as it is impracticable to effect-this adjustment by the winding 8 alone, owing to the presence of resistance. I'employ a wind ing 9, which is preferably stationary, and place it in cooperative and magnetic coaxial relation with the armature and use reactance.

for adj usting the phase of the current in said winding 9. In the arrangement shown in Fig. 1 I include a portion of the winding Sin a closed circuit with-the winding9, adjust ing ohmic resistance 10 being included in said closed circuit. The-result of these instru-- mentalities is illustrated in Fig. 2, where a 1) represents the line-pressure a c, the magnetism due to the armature; a d, the magnetism due to current in that portion of the winding 8 which flows through the stationary shuntwinding 9, and a e the resultant magnetic field of force representing the impressed electromotive force in quadrature with a b, being the resultant of the magnetism at c of the armature and the magnetism Ct 01 of the winding 9. The magnitude of the component ct d is adjusted by means of theresistance 10.

In the apparatus shown in Fig. 3 I cause the current in the winding 9 tolag one hun-.

dred and eighty degrees or. more behind the impressed electromotive force by winding about the impedance-winding 8' a few turns of wire 11, which constitute a secondary, and including the secondaryll incircuit with The resistance 10 serves to adjust the current. The same result might be accomplished by-including-the winding 9 in a closed circuit with an adjusting resist-,

In the apparatus shown in Fig. LI-supply the winding 9 directly from the mains, between which it is included inbridge, the resistance 10 serving to adjust the amount of (Shown in dotted lines.) Inthis arrangement the armature is used as an inducing-winding instead of-the winding 8.

'75 causes current through the armature to lag series coils 5 to prevent mutual inductiou.

In Fig. 3 the magnetic axis of the armature .3 is indicated by the dotted lines to at, which is also the magnetic axis of the shunt-coils 9, While the magnetic axis of the series or ampere coils is indicated by the dotted liney z.

While I have herein shown and particularly described some embodiments of my invention, it is obvious that other embodiments thereof may be devised without departing from the spirit of the invention, and I do not bination with a revoluble armature havinga' field-prod ucing winding, of a second winding in cooperative relation therewith for producing a resultant magnetic field in quadrature.

with the pressure, substantially as described. 2. In an alternating-current meter the combination, with a revoluble armature having a field-producing winding, of a second station- I ary winding in cooperative relation therewith for producing a resultant magnetic field in quadrature with the pressure, substantiallyv as described.

3. In an alternating-current meter/the combination with a revoluble armature having a field-producing winding, of a second winding in cooperative relation therewith for producing a resultant magnetic field in quadrature with the pressure, and a stationary field-winding associated with the armature, substantially as described.

4. In an alternating-cu rrent meter,the combination with a revoluble armature havinga field-producing winding, of a second stationary winding in cooperative relation therewith for producing a resultant magneticfield in quadrature with the pressure, and a stationary field-winding associated with the armature, substantially as described.

5. In an alternating-current motor,the combination with a pressure-Winding, of a second field-winding, one of the said windings being revoluble,meansforindependentlysupplying current to the said windings from an external source and a phase-modifying winding in cooperative relation with the pressure-winding, substantially as described.

6. In an alternating-current motor,the combination with a pressure-winding, ofa second field-winding, one of the said windings being revoluble, means for independently supplying current to the said windings from an external source anda phase-modifyingstationary winding in cooperative relation with the pressure-winding, substantially as described.

7. Inanalternating-currentmotor,thecombination with two field-windings, one of which is movable, of a phase-modifying winding in cooperative relation with one of said fieldwindings adapted to maintain the phase of the field due thereto substantially in quadra ture with the pressure, substantially as described.

8. In an alternating-current motor,the combination with two field-windings, one of which is movable, of a phase-modifying winding in codperativerelation with one of said fieldwindings adapted to maintain the phase of the field due thereto substantially in quadrature with the pressure, and a commutator for supplying current to the movable winding, substantially as'described.

9. In an alternating-current meter, the co mbination with pressure and ampere field-windings, one of which is movable, of a phasemodifying winding in cooperative relation with the pressure-winding and adapted to maintain the resultant magnetic field due to the latter winding substantially in quadrature with the pressure, substantially as described.

10. In an alternating-current meter, the combination with pressure and ampere fieldwindings, one of which is movable, of a phase modifyingwinding in cooperative relation with the pressure-Winding and adapted to maintain the resultant magnetic field due to the latter winding substantially in quadratu re with the pressure, and a commutator for including the movable winding in circuit, substantially as described.

11. In an alternating-current meter, the combination with pressure and ampere fieldwindings, thepressure-winding being rotatable, of a phase-modifying winding in cooperative relation with the pressure-winding for maintaining the phase of the resultant magnetism due to the pressure-winding substantially in quadrature with the pressure, substantially as described.

12. In an alternating-current meter, the combination with pressure and ampere fieldwindings, the pressure-winding being rotatable, of a phase-modifying winding in cooperative relation with the pressure-winding for maintaining the phase of the resultant magnetism due to the pressure-winding substantially in quadrature with the pressure, and a commutator for including the pressurewinding in circuit, substantially as described.

13. In an alternating-current meter, the combination with pressure and ampere fieldwindings, the pressure-winding being rotatable, of a phase-modifying winding in cooperative relation with the pressure-winding for maintaining the phase of the resultant magnetism due to the pressure-winding substantially in quadrature with the pressure, and adjusting means for determining the current in the phase-modifying winding, substantially as described.

14. In an alternating-current meter, the combination with pressure and ampere fieldwindings, the pressure-winding being rotatable, of a phase-modifying winding in cooperative relation with the pressure-winding for nation with an alternating-current generator, of pressure and ampere windings in circuit" therewith, the pressure-winding being mov- 1 able tohave it serve by its motion-to measure the wattless component of the current, of a phase-modifying winding supplied with current also from said source, and being in cooperative relation with the pressure-winding to produce and maintain a field substantially in quadrature with the pressure,substantially as described.

16. In a system of distribution, the combination withan alternating-current generator,

of pressure and ampere windings in circuit therewith, the pressure-winding being movable to have it serve by its motion to measure the wattless component of the current, of

aphase-modifying winding supplied with current also from said source, and being in cooperative relation with the pressure-winding to produce and maintain a field substantially in quadrature with the pressure, and a commutator for including the pressure-winding in circuit, substantially as described.

17. In a system of distribution, the combination with an alternating-current generator, of pressure and ampere windings in circuit therewith, the pressure-winding being movable to have it serve by its motion to measure the wattless component of the current, of a phase-modifying winding supplied with current also from said source, and being in cooperative relation with the pressure-winding to produce and maintain a field substantially in quadrature with the pressure, the phasemodifying winding and the am pere field-wind ing being at right angles to prevent mutual induction, substantially as described.

18. In a system of distribution, the combination with an altern ating-current generator, of pressure and ampere windings in circuit therewith, the pressure-winding being movable to have it serve by its motion to measure the wattless component of the current, of a phase-modifying winding supplied with current also from said source and being in cooperative relation with the pressure-winding to produceand maintain a field substantially in quadrature with the pressure, and a commutator for including the pressure-winding in circuit, the phase-modifying winding and the ampere field-winding being at right angles to prevent mutual induction, substantially as described.

19. In a system of alternating-current distribution, the combination with an alternating-current generator, of a rotatable pressure-windin gfor measuring by its m otion the pressure, the current in thephase-modifying winding,

.wattless component of alternating currents, inductance in circuit with said winding, a phase-modifying winding in cooperative relation with the pressure-winding for maintaining the resultant field due thereto substantially in quadrature with the pressure andan ampere-winding cooperating with the pressure-winding to produce a torque varying as the sine of the angle of lag between the current and pressure, substantially as described.

20. In a system of alternating-current distribution, the combination with an alternating-current generator,ota rotatable pressurewinding for measuringby its motion the wattless component of alternating currents, inductance in circuit with said winding,aphase modifying winding in cooperative relation with the pressure-winding for maintaining the resultant field due thereto substantially in quadat-ure with the pressure, an amperewindiug cooperating with the pressure-winding to produce a torque varying as the sine of the angle of lag between the current and pressure, and adjusting means for-determining the currentin the phase-modifyingwinding, substantially as described.

2t. In a system of alternating-current distribution, the combination with an alternatin g current generator, of a rotatable pressurewinding for measuring by its motion the wattless component of alternating currents,\ind uctance in circuit with said winding,a phasemodifying winding in cooperative relation with the pressure-winding for maintaining the resultant field due thereto substantially in quadrature with the pressure, an amperewinding cooperating with the pressure-Winding to produce a torque varying as the sine of the angle of lag between the current and pressure, and a commutator for including the pressure-winding in circuit, substantially as described.

22. In a system of alternating-current distribution, the combinationwith an alternating-cu rren t generator,of a rotatable pressurewinding for measuring by its motion the wattless component of alternating currents, inductance in circuit with said winding,a phasemodifying winding in cooperative relation with the pressure-winding for maintaining the resultant field due thereto substantially in quadrature with the pressure, an amperewinding cooperating with the pressure-winding to produce a torque varying as the sine of the angle of lag between the current and adjusting meansfor determining and a com mutator forincluding the pressurewindin g in circuit, substantially as described.

23. In a system of alternating-current distribution, the combination with an alternat ing-current gen erator,0f a rotatable pressurewinding for measuring by its motion the wattless component of alternating currents, in-

ductance in circuit with said winding,a phasemodifying winding in coeperativ-e relation 'with the pressure-winding for maintaining the resultant field due thereto substantially in quadrature with the pressure, an amperewinding codperating with the pressure-winding to produce a torque varying as the sine of the angle of lag between the current and pressure, and adjusting means for determining the currentin the phase-modifying \vind ing, substantially as described.

In witness whereof I hereunto subscribe my I name this 31st day ofOctober, A. D. 1899. THOMAS DUNCAN.

Witnesses:

CHARLES A. BROXVNV CHARLES E. HUBER'r.

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