US1077626A - Alternating-current apparatus. - Google Patents

Description

R. 1). MERSH-ON ALTERNATING CURRENT APPARATUS. APPLICATION FILED APR. 27, 1910. RENEWED MAY 24, 1913.

1,077,626, Patented Nov.4,1913.

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R. D. ME RSHON. ALTERNATING CURRENT APPABATU S. APPLICATION FILED APB.. 27, 1 910'. RENEWED MAY 24, 1913.

1,077,626, Patented Nov. 4, 1913.

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R. D. MERSHON. ALTERNATING CURRENT APPARATUS. APPLICATION FILED APR.27, 1910. RENEWED MAY 24, 1913.

1,077,626, Patented Nov. 4, 1913.

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1,077,626. Patented N0v.4, 1913.

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R. D. MERSHON.

ALTERNATING CURRENT APPARATUS. APPLICATION FILED APR. 27, 1910. RENEWED MAY 24, 1013.

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RALPH D. MERSHON. 3? NEW YORK, N. Y.

ALTERNATINGCURRENT APPARATUS.

Application filed April 2'5; 1910, Serial No. 557.88? Renewed May 24. 511; Scri lhii known that l. ltnru l). Mrnsnox. a citizen of thc l'nitcd iates. residing at New York. in the county and State ol .\c\\' Y rli, have invcuicd certain new and useful Improvements in .\h rnating(urrcnt Apparatus. ot which the following is a full. clear. and cXact description.

This invention l(lllttr to polyphasc electrical ap iaratus, such as motors and generators, rotary converters, etc.. and its hief object. stated generally. is t provide means whereby such apparatus may be operated on single-phase circuits, with results conr parable to those obtained on polyphase circuitS.

To this and other ends the invention consists in the novel features of construction. arrangements of )arts, and combinations of elements hereina ter described' Several convenient and etl'ective cmbodi' ments of the invention are illustrated diagrammatically in the accompanying drawings, and referring now thereto, Figures 1, 2 and 3 show in simple diagram various ways of operating a polyphase motor on a singlephase circuit. Fig. 4 is a diagrammatic representation of the method illustrated in Fig. 8, but with non-inductive motor circuits. Figs. 5 and 6 are vector diagrams representing various electrical conditions in the apparatus. Figs. 7, 8 and 9 are diagrams illustrating three Ways of applying my invention when the motor-circuits are non-inductive. or have their reactance neutralized so as to make them equivalently non-inductive. Fig. 10 is a diagram representing the electrical equivalent of an induction motor. Fig. 11 is a diagram illustrating a mode of applying the invention, when the motor-circuits arc inductive, Without neutralization of their rcactance. Fig. 12 is a diagram illustrating a modification of the latter scheme.

As is well known, polyphase apparatus may be operated on a single-phase circuit by employing in connection with the apparatus a suitable combination of phase advancing and retardingdevices, or, in gen eral, phase-modifying means, f or example capacity and reactance. Thus in Fig. 1 the three-phase motor M may oe.run oncu'rrent from the single base source S by connecting across one o the phase windmgs a Specification of Letters Pa-eu atcutcd Roy. 4.1913.

ndenser l and across airuicr :1 l'cactuncc if. Sin'iilarly a two phasc, m .praHer-pha e, machine may be Ulltl'iilttl oi; a single pha-r circuit. as y means of the arrangcmcnis -h \\'n in Fig 2 and 11. In lh first oi the last-named i'zgnrc the two pha es of the motor a re in serie with the capacity 3 and the reactan 'c -l in shunt t the rcspcctiw cir uits: while in Fig. the two motor-circu ts are independently connected to the source. one through the rcactance. 5. and one through the capacity. (3. The arrange ment shown in Fig. I) is also illustrated in Fig. l, in which, however, the motor cii uits are represented by the adjustable non inductive resistances 7, 8. It now the values of the rcactance 9 and capacity 10 are properly proportioned to the resistances T. 8, the currents in the two phaseovindiiigs (represented by T. H, as previously stated) will be in quadrature. This condition may be represented by the vector diagram Fig. 5. in which E is the impressed E. M. F.. on and 0c are the components of E. M. F. consumed in the resistances 7, 8, respectively and the other sides of the two triangles. (1b and 0b, are the components of E. M. F. consumed in the reactance 9 and capacity 10 respectively.

Suppose now that the values of 7 and 8 be varied by the same amount. simultaneously. The triangles in the vector diagram will change correspondingly. for example to one or another of the forms shown in full lines in Fig. (i; a diminution giving the triangles 00?) and 06d, for instance, and an increase giving the triangles of?) and 0gb. It will therefore be seen that if the power taken by the resistances. or in other words the current therethrough, be varied by varying the resistances alone, the quarter-phase or quadrature relation of these components will be destroyed, givinga relation greater or less than 90? as the case may be. The quadrature relation may, however, be restored by increasing or decreasing, as may be required, the reactance and capacity components of E. M. F., by varying the values of the reactance 9 and capacity 10. On the other hand the quadrature relation will be maintained, when the power taken by the two resistances is varied, if the power-variation is produced not by varying the resistances but. by varying the voltage impressed on the entire combination; since in this case the relation of resistance'and reactance 0n the one hand, and of resistance and capacity on the other, remains unaltered. This is equivalent to varying the impressed voltage as the square root of the power required.

The maintenance of a proper phase relation in the poiyphase circuits (for example W in two-phase apparatus, (30" in three phase, etc), is a matter of the utmost importance in the operation of polyphase apparatus on single-phasc circuits, and it is accordingly the chief object of my present invention to provide means for accomplishing the desired maintenance of phaserelation. In carrying out the invention the desired control may be e'liected automatically, in various ways. For example it may be dependent upon variation of the total amount of power taken by the motor. This method illustrated in Fig. 7, in Which a quarterphase motor is shown at 11, with phase windings 1i, 1-5, fed from a single-phase source 14 through a transformer 15. 16 is a deviceoperating on the wattmeter principle, having a pivoted shunt coil 17 connected across the transformer terminals, and a stationary series coil 18 in the motor circuit. The shunt coil has an arm 15) playing over a series of contacts 20 brought out from the transformer, and the arm is in series with the circuit of the field coil 18. The circuit of the shunt coil contains the usual noirinductive resistance 21. The external reactance and capacity are shown at 22 and y 23 respectively.

From the foregoing the operation of the system will be readily understood.

As the total power taken by the motor varies. in one direction or another from a predetermined value which for convenience may be termed the normal value, the shunt coil 17 will turn and the arm 19 will move over the taps or terminals 20, cutting transformer turns in or out of the motor circuit as the case may be: it being understood, of course. that in designing the apparatus due regard will be had to the fact that the transformer turns out in or out must be such as to keep the impressed voltage equal to /2 times the power required by the motor. It may here be noted that the external reactance 22 and capacity 23 are. in series with the respective motor-circuits. as in Fig. it, this arrangement being selected merely for the purpose of exemplifying one method of connecting these elements when my invention is employed.

By reference to Fig. (3 it will be seen that when the phasc-rclation departs from normal not only do the angles between the im pressed E. M. l. and the components vary, but the relative values of the components vary also. Thus under normal conditions the components ab and 0c are in phase and equal, as are also 011 and 06. Under abnormal conditions they are out of phase and unequal. Under normal conditions 0a and a?) are in quadrature and equal, while under abnormal conditions they are unequal though still in quadrature: likewise 0c and (:6. These variations may be availed of for the purposes of my invention by employing as the controlling device one which depends for its operation upon change in the phase relation of the component's mentioned, or upon change in their values. An example of the first of these methods, in which variation in the phase-relation of the components mentioned is the controlling factor, is illustrated in Fig. 8. Here, for the sake of sinr plicity in the diagram. the motor circuits are shown as simple non-inductive resistances 24, 25. .\n auxiliary two-phase motor is employed. one'phase of which is connected across 0/) and the other across 0a, as indicated in the figure. Under normal conditions, when these components are in phase, the auxiliary motor exerts no torque and is therefore stationary; but when the phase relation disturbed the auxiliary motor develops torque and the pinion 27 on the rotor will advance (or retract, as the case may be) the rack 28 carrying the contact member 29 across the terminals of the variable reactance 30 and variable capacity 31, cutting reactance and capacity in or out of the motor circuits until the normal phase relation of the components a?) and 0c is restored, whereupon the auxiliary motor ceases to exert torque and the contact member comes to rest. in this scheme the torque developed by the adjusting device (the auxiliary motor 26), and hence its speed of operation, depend upon the degree of diston tion or depart are from the normal phase rclation, and diminish as the adjustment brings about an approach to normal conditions. That is, the adjusting device slows up, more or less, as the phase relation approaches the normal. It will also be observed that the direction of movement of the controlling device depends upon the direction of the abnormality, so to speak. Thus a condition which would bring about a condition represented by the triangles 0e?) and odb, for example, would produce a movement of the contact member 29 in one direction (toward the left in Fig. 8), and a condition represented by the triangles 0f?) and 0gb vould cause movement of the contact member in the opposite direction.

As previously stated, difference in the values of the components involved may be employed for the purpose of control. This scheme is illustrated in Fig. 9, in which, as in Fig. 8, an auxiliary motor, 32, is provided to move the contact member 33; across the variable reactance 34 and capacity 35. The operation and direction of movement of the orneas auxiliary motor ing switch 36, whose arm 37 is actuated by a lever 38 having its ends attached to the cores of two solenoids 3t), 40. One of these coils, 39, is connected across (:7), and the other. 40. across m, as indicated in the figurev it will now be seen that as long as these omponents are equal,

they are no longer equal. one solenoid will overhalanctthe other and throw the switch,

starting the motor in the corresponding direction. oon a the components re terred to are again eipial the solenoids will again be in balance and the switch will be re tored to neutral position. In the s heme lllll ll'ilt(?(l in Fig. 9. as in Fig. 8, the reactance ill and the capacity 35 are in series with the respective circuits of the main niotor. (these circuits being represented by the non'inductive resistance 4t. 42). but of cour e the invention is not limited to that particular mode of connection.

It will be noted that throughout the foregoing explanation of Figs. 8 and 9 the poly phase power circuits of the motor are as sinned to be non-inductive. If they are not they may be made equivalently non-inductive (for example by the employment of condensers 43, 44, Fig. 7, in the manner described in my copending application Ser. No. 557,979, filed of even date herewith) if the motor has a short-circuited secondary or if such resistance as is introduced thereinto does not carry with it any reactance or capacity; that is, if the reaetance elements of each circuit of the motor are constant. Under such circumstances all the polyphase power circuits can be controlled by a single device, (an auxiliary motor for example), as in Figs. 7, 8, and 9. But if the desired regulation is to be eti'ected regardless of the condition of the secondary, whether inductive or non-inductive, shortcircuited or containing variable resistance or capacity, etc, it is, in general, necessary to have a regulating device or mechanism for each polyphasc power circuit in which regulation is required. Moreover, in the preceding description the external reactance and capacity were in series with the circuits of the motor, but they may be in multiple with the respectire circuits. The preferred method of applying my invention under such conditions will now be described, confining the description, for the sake of brevity, to a three-phase motor. understood that the invention is not restricted to any particular number of phases.

Referring to Fig. 10, it will be recognized that this figure represents the electrical and their dit- 'l'ercn e therefore zero. the pull exerted by one solenoid will balance. that exerted by the It will, however, be

l l l are controlled by a reversequivalent of a three-phase induction motor with external rcactance and capacity. connected as in Fig. 1, tor example, to enable it to operate on a single phase circuit. Such resistance as would be introduced into the motor secondary is represented by the ad-- justablc resistances 45, l6, ii. in series with these resistances are the reactan es la, 49. fit), representing the variable reactant-es which might be introduced as l5, 4t), 47 are Varied. 5i (32 inclusive are reactanccs ol' the primary and secondary, due to stray field; and 03, (ll, t3?) represent reactances ach taking current equal to the no load magnetizingcurrent of its respective, motor-circuit. It may be noted here that 18 (35, any or all of them, might be apacity so far as the general solution ol' the problem is concerned; but in practice they would usually be rcactances, as indicated. In any case the total current taken by any one circuit of the motor may be considered as split up into two components 9U apart. ()ne of these components is in step with the electromotive force impressed upon the motor circuit, and. represents the power expended in the resistance 45, 46, or 47, as the case may be, and in such resistance as the reactanccs in such circuit might have. This component of current we may denote generally by r. The other component of current, which is 90 away from the E. M. F. impressed upon the motor circuit, represents the component of current for the magnetizing of the reactances in he circuit, and may be denoted generally by R.

The proper analytical investigation shows that, in order to have balanced thrce-phase in the circuits of Fig. 10 when single-phase E. M. F. is supplied to the terminals (3, 67, the following conditions must obtain:

1. The current of the external rcactance 68, which current may be denoted by R, plus the total reactance current, R, of the motor circuit across which 68 is connected, must be equal to /3 times the Work current 1" of such circuit. That is, R+1t=r {3i Or, if 49, 55, 56, 57, 58, (54 represent capacity, RR=r /3.

The current, C, of the external capacity (39, minus the total reactance current R, of the circuit across which 69 is connected. must'bc /3 times the work current 1" of such circuit. That is, CR=r Or, if 50, 59, (30, 6 1 62, 65 represent capacity, C+R=r tinues, a point Will be reached at which, in order to preserve the above relation, the rev actance 68 must be increased till its current is zero. At this point R=r But suppose 46 be still further increased, with corresponding diminution of its current 1". It may be impracticable or even impossible to vary t at this stage, in order to preserve the J3 ratio, but we can in effect neutralize R by substituting capacity for the external re actance ($8; an expedient which is equivalent to making the current R negative and giving it the proper absolute value to keep R' +R=r #3. It may be noted that the same reasoning applies when 49, 55, 56, 57, 58, (i l represent capacity if at the beginning (38 also represents capacity and changes to reactance at the point Where R=r J3.

In phase B, which has the external capacity 60 in parallel with it, CR must equal 1" /3, as previously stated. Hence as the work current 1* of this phase diminishes, the condenser current 0 must be decreased. If capacity were connected-t0 the motor secondary, then C would have to be still further dcc eased. If the value of the capacity in the secondary were increased, the current to (it) would have to be decreased coincidentally until it had fallen to zero, and if the increase of the secondary capacity were carried far enough 69 would have to be replaced by reactance.

The relations thus briefly outlined can be readily availed of for the purposes of my invention, for example by the means illustrated in Fig. 11. In this figure 70 designates the polyphase motor (three-phase), and 71 is the source of single phase current. The motor secondary may be short-circuited or have inserted in it resistance, capacity, or reactance, or any two or all three of the same, a short-circuited secondary of the squirrel cage type being shown in the figure, designated by b. Across one of the derived phases a variable reactance 72 and a variable capacity 73 are connected, and across the other derived phase are similar reactance and capacity, designated by 74 and 75 respectively. These two phases might have a common terminal at 76, with either delta or a winding, but for the sake of clearness a terminal for each phase at this point'is shown. The terminal contacts 77, 78, of the reactances and condensers just mentioned, are arranged to coope "ate with two pivoted sectors 79, 80, so that the movement of sector 79, for example clockwise from the position shown in the figure, will cut out more and more of the multiple reactances (thereby de creasing the current of the external reactance, in accordance with the explanation given above), and finally cut in more and more capacity. Movement in the opposite direction will of course reverse the operal l l l l l l tion. In the other phase, counterclockwise movement of sector from the position shown cuts out more and more of the multiple capacity 75 and finally cut. in more and more of the multiple rcactance 74. Of course such movement of the sector, past one set oftaps and onto the next set, as would put the sector in contact With both sets, would accomplish an equivalent result, but the consequent increased loss in the reactance capacity device makes the other scheme in general more desirable. Suitably located steps 21, u, are provided to limit the movements of the sectors.

The sectors are actuated, through the instrumentality of worms and worm-gears, by small auxiliary induction motors 83, 84, (three-phase in the present instance), whose operation, and direction of rotation, are controlled by reversing switches 85, 86. The arms 87 and 88 of these switches play between contacts 89, 90, 91, 92, in the circuits of the auxiliary motors, and are actuated by the devices 93, 94, so that engagement of the switch arm 87 With the contacts 89, for example, will cause the auxiliary motor 83 to run in one direction, While engagement with the opposite contacts will cause movement in the opposite direction. The operation of switch 86 is of course exactly similar. The condensers 95 and 00, in the circuits of the auxiliary motors, enable these motors to run in either direction, as will be readily understood.

The switeh arms 8 88 are connected to and actuated by the devices 03, 04. As these latter are similar in construction and operation a description of one will serve for both.

The device 93, pivoted at its center, has three arms 97, 98, 9!), carrying the voltage coils 100, 101, 102, respectively, and adjacent to these latter are three stationary current-coils 103. 104, 105. The current coil 103 is in series with the motor circuit (through one of the taps at 70 in Fig. 11) so that the current of the motor circuit passes through it: and through the adjacent; voltage-coil 100 'iasscs a current proportional to the voltage impressed upon the corresponding circuit. of the motor but in quadrature therewith (lagging 00) by reason of a suitably proportioned reactaneelOG. The torque, which may be den ted by T, produced between coils 100 and 103 is therefore proportional to the quadrature component of the motor-circuit current. The total current made up of the motoncircuit current and the current from the reactancecapacity 72-73 pas:-es through the currentcoil 105 while through the adjacent voltagecoil 102 passes a current whose v tage is proportional to and in step with the E. M. F.

impressed on the motor-circuit. The torque of coils 102 and 105, which torque may be in 72T3.

denoted by t, is therefore proportional to the power-current component, 7", of the total current; and it is to be noted that the cooperating coils just mentioned take account of the total power consumed, in the phase in which they are connected, including the loss The current It, of 72 73, also asse.s through the current, coil 10 t, and through the adjacent voltage coil 101 passes a current proportional to the impressed E. M. F. but in quadrature. with it by rea* son of a suitably proportioned reactance 107. Hence the torque, T, of the two coils last named. is proportional to the quadrature component of the current from 72*73, such current being all quadrature current except for the small component accounting for the loss in 72 73. The number of turns in coil 105 is J3 times the number in each of the other two current coils. Now the coils 100-103, 101-10 1, are so connected and ar ranged that their torques are additive when the current in the motor-circuit lags, (that is, when R is reactance current), while the coils 102 105 are so connected that their torque opposes the sum (algebraic) of the torques of the other two sets of coils. \Ve therefore have the relation T+T:t, when R'+R, (or R if R is condenser current), =1' /3. The device 93 is then stationary, with the switch arm 87 in its neutral position, and hence the auxiliary motor 83 is inactive. But suppose r should vary, decreasing, for example, to a certain value. The device 93 will then be unbalanced, turning clockwise, for example, and the switch arm will bridge the upper pair of contacts, 89. The auxiliary motor 83 Will then instantly start in the corresponding direction, turning the sector 79 clockwise and cutting out more and more of the multiple reaetance 72, even throwing in the capacity 73 it necessary, until R +R is again equal to 1 J3 At this point the polyphase currents in the motor are again in balance, the torque t is again equal to the algebraic sum of torques T and T, and the springs m, g at once return the device 93 to its neutral position, thereby breaking the circuit of the auxiliary motor 83 and stopping the sector '79. Now suppose the work current to increase from its last value. The operation described will be reversed. and the sector will turn counterclockwise until the balanced polyphase relation in the main motor is restored.

During the above operations the device 9t turns counter-clockwise and the auxiliary motor 8-1 turns the sector 80 in the same direction: it. being remembered that in this phase. C R, (or It if R is condenser current), =r B when the desired polyphase relation of currents and E. M. Fs in the main motor obtains. It will be observed that in 5 this phase the direction of the current power from a polyphase generator.

through current coil 105 with respect to the direction through the cooperating voltage coil is the opposite of that in the other phase, since the auxiliary motor and sector of the one phase must in general move in a direction opposite to that in the other phase.

From the foregoing it will be seen that the devices 93, 91 take account of variation of the work current and the change in the internal reactance current R (or capacity current, as the case may be) incident to such variation, and through the instrnmentality of the auxiliary motors S3, S4, and the reactance-capacity combinations, 72 HTS, maintain the balanced polyphase relation in the polyphase circuits of the motor 70 Inasmuch as two of the voltage or shunt coils in each controlling instrument, 93, 91, have reactanccs (or capacity, if desired) in series with them these instruments will be atlected by change of frequency. If such change is not great the effects will be immaterial, otherwise the results may be more serious. This difficulty may'be avoided by using an instrument in which the coils 100, 103, and 101, 104, (acting on the dynamomefer principle), are replaced by stationary coils acting on metal sectors, in the manner of an induction watthour meter, which are fastened to the appropriate arms of the pivoted controlling device. This scheme is illustrated in Fig. 12, in which the external reactancecondenser combinations 72-73, 7r75 the auxiliary motors 83, 84*, the sectors 79, 80 reversing switches 85, 86 and coils-102*, 105", and other elements, correspond exactly, in construction and operation, to the similarly lettered parts in Fig. 11. The arms 97 99 of the controlling instruments 93*, 94 carry metal plates or sectors 108, 109. On one side of these plates are stationary current coils and on the other side stationary voltage coils 112, 113, the latter, and the voltagecoils 102, having non-inductive resistances 114 in series with them.

From the principles of the induction watthour meter it will now be seen that the torque ,of each induction element on each controlling instrument in Fig. 1.2 will be proportional to that component, of the main :urrentpassin through the respective induction element, which is in quadrature to the impressed E. M. F., just as in the case of the corresponding elements of Fig. 11', but that the torques on the arms. and hence the resultant torque on each device, will be independent of the frequency.

The foregoing explanations have been confined to induction motors, but it will be understood by those skilled in the art that A The generator may then be loaded symmetrically and its full polyphase capacity can be realiZed, instead of the reduced capacity resulting when single-phase'power is taken from one phase only.

It will also be understood that the invention is not limited to the forms herein specifically illustrated and described but is capable of various other embodiments without departure from its proper spirit and scope.

I claim:

1. The combination of electrical apparatus having polyphase circuits, adjustable phase-modifying means connected with said circuits to enable the apparatus to operate on a single phase circuit, and automatic means for adjusting said phase-modifying means to maintain a given phase-relation in the polyphase circuits of the apparatus.

2. The combination of a single-phase circuit; electrical apparatus connected therewith and having polyphase circuits; adjustable reactance and capacity connected with the polyphase circuits to give a desired phase-relation therein; and automatic adjusting means for the reactance and capacity, to restore the desired phase-relation when the same is departed from.

3. The combination of a single-phase circuit, electrical apparatus connected therewith and having polyphase circuits, external reactance and capacity connected with the polyphase circuits for the production of a desired phase-relation therein, and automatic means for varying the external reactance and capacity as the current in the said apparatus varies, whereby to maintain the desired phase-relation.

4. The combination of an alternating current motor having polyphase circuits, phasemodifying means connected with the motor for the production of a desired polyphase relation in said circuits when the motor is supplied from a single-phase source, and automatic means for controlling the phase modifying means to maintain the desired phase-relation in said polyphase circuits.

5. The combination of an alternating current motor having polyphase circuits, external reactance and capacity connected with said circuits for the production of a given polyphase relation therein, and automatic means for varying the external reactance and capacity to maintain the given phase relation in said polyphase circuits.

6. The combination of an alternating current motor having polyphase circuits, external phase-modifying devices connected with the motor for the production of a given po1y-' phase relation in said circuits when the motor is supplied from a single-phase source, and automatic means, dependent for operation upon variation of the powerand reactance: components, for regulating the phase-modifying devices to maintain the desired polyphase relation in said polyphase circuits.

7. The combination of an alternating current motor having olyphase'circuits, adjustable phase-modi ying devices connected therewith for the production of a desired polyphase relation in said circuits when the motor is supplied from a single-phase source, an auxiliary motor operat-ively connected with the phase-modifying devices to adjust the same, and automatic controlling means 101 said auxiliary motor, dependent for operation upon departure from said desired polyphase relation.

8. The combination of a main alternating current motor having polyphase circuits, adjustable phase-modifying devices connected therewith for the production of polyphase currents with a given polyphase relation in said circuits when the motor is supplied from a single-phase source, an auxiliary motor associated with the phase-modifying devices to adjust the same, and automatic means for controlling the auxiliary motor, dependent for operation upon variation in the powerand reactance-components, to maintain the given phase-relation of said polyphase currents.

9. The combination of an alternating current motor having main and derived-phase circuits; an adjustable phase-modifyin device for each derived-phase circuit; an automatic devices, for adjusting the phasemodifying devices; dependent for operation upon variation of the powerand reactancecomponents, to maintain a given polyphase relation of currents in the motor circuits.

10. In an alternating current motor having main and derived-phase circuits, the combination with a derived-phase circuit, of an adjustable reactance-capacit device, for producing a desired relation 0 the current of'said device and components of current in the said derived-phase circuit, and automatic adjusting means for said device, dependent for operation upon departure from said desired relation.

11. In an alternating current motor having main and derived-phase circuits, the combination with a derived-phase circuit, of an adjustable reactance-capacity device connected therewith, an auxiliary motor assoeiated with said device to adjust the same, and automatic controlling means for the auxiliary motor, dependent for operation upon variation of components of current in the said derived-phase circuit, whereby to maintain a desired relation of said components and the current of the reactancecapacity device.

12. The combination of an alternating current motor having main and derivedphase clrcuits, adjustable phase-modifying means connected with the motor for the 13. The combination of an alternating current apparatus having polyphase circuits, adjustable phase-modifying means for oducing a desired polyphase relation in said circuits when the apparatus is operated on a single-phase circuit, and automatic adjustin means for the phase-modifying means, in ependent of the frequency of said currents and dependent for operation upon departure from the desired polyphase relation in said polyphase circuits.

In testimony whereof I afiix my signature in the presence of two subscribing witnesses.

RALPH D. MERSHON. Witnesses:

BERT. R. SANDMAN, S. S. DURHAM.

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