US2089860A - Slow transformer - Google Patents

Description

Aug. 10, 1937. A. B. RYPlNsKl l SLOW TRANSFORMER Filed March l, 1955 w d'hlm Pannes Aug. 1o, 1937 2,039,350,

UNITED STATES PATENT OFFICE SLOW TRANSFORMER Albert B. Rypinski, Laurelton, Long Island, N. Y. Application March 1, 1935, Serial No. 8,913 13 Claims. (Cl. 171119) This application is a continuation-impart of and made up of materials having different temmy copending application Serial No. 671,767, for perature coefficients of resistance. This also ap- Slow electromagnets having the same or similar plies to applications, Serial Nos. 699,616; 699,618; temperature coeiiicients of resistance materials and 699,620. Any of the other continuation-in- 5 in differential windings, led May 18, 1933, and part applications based on application Serial No. 5

its divisional application, Serial No. 705,466, for 416,877 are similarly limited.

Slow electromagnetic devices having different In application, Serial'No. 671,767, in describtemperature coeicient of resistance materials in ing the effects of arrangement and heating, the assistant windings, filed January 5, 1934. following statement is made: If applied to a My related applications and patent which will transformer u the magnetism will alter 10 be referred to are listed below: in the same way,l as above described. All of S. N. 416,877-led Dec. 27, 1929for Slow the claims specific to transformers have been magnetic regulating devices, S. N. 699,616-led transferred from aDDliCatlOIl, Serial N0 671,767 Nov. 24, 1933-for Motor starting systems, S. N. to this application. They include slow trans- 17 699,6l7-led Nov. 24, 1933-for Signaling sysformers having the same or similar temperature 15 tems, S, N. 699,618-led Nov. 24, 1933-for Mocoeilcient of resistance material in paralleled optor control system, S. N. 699,619-led Nov. 24, posed windings. l933-for Distribution system, S. N. 699,620- In application, Serial No. 705,466, it is stated: filed Nov. 24, 1933-for Arc welding apparatus, y invention relates broadly to transform- 20 s; N, 703,313 ii1ed Dec. 20, 1933f0r High temers and particularly to structures thereof emperature s1ow electromagnetic device and Patent ploying various temperature coefficient of resiste 20 No. 1,972,319, dated September 4, 1934, S, N, ance materials in assisting windings of the de- 671,768 led May 1'8, 1933-for C0115 for slow vices. All of the claims in application Serial No. electromagnets and reactors. 705,466 specic to transformers have been n- Throughout these various applications, there corporated herein. 25 are many showings, descriptions and claims for One of the objects of my present invention is slow transformers, a term I apply to a transto produce a slow transformer as described in former in which the magnetism and its resultant applications Serial NOSl 671,767 and 705,465 effects are caused to vary over a time cycle by wherein the paralleled windings have the Same means of my invention. p temperature coeiiicients of resistance either op- 30 In every instance, I employ two inductively posed to or assisting one another, or having difrespect to the other, the resultant magnetism beassisting one another.

ing changed over a time cycle either by changes A further object of my present invention is to produce a slow transformer utilizing any of 3f windings, or by changes in the circuit current, the means disclosed in the Various applications Any such winding, when supplied with alternatreferred to to alter the voltage, current, resistance, ing or varying current necessarily exhibits a impedance, power factor or magnetism in a transtransformer action in that the nux set upby one former for any of the uses in the applications 40 winding threads through and induces a voltage cited. I may employ different numbers of turns 40 plies to the effects of mutual induction between unequally. I may employ Constructions resultthe paralleled windings, where these windings are ing in Substantially Complete flllX interlnkage the only ones involved. This has been disclosed between the paralleled windings, aS SliOWn in my 4" and claimed in a number of the above cases. patent N0. 1,972,319 Where 011e COIldllCtOI iS Spistituted by two inductively coupled windings concoupling leakage ilux will circulate locally around nected in parallel. Slow transformers of this type windings I6 and I1 without traversing the enare shown in my application, Serial No. 416,877, tire core I9 and 20, particularly when the air but are limited therein to those in which the gans 22 and 23 are open; differential heating or paralleled windings are connected in opposition Cooling of the paralleled windings by any well- 55 known method employing radiation, convection, .conduction or diffusion of heat; movable or stationary cores in the magnetic circuit as illustrated in the drawing; switching means in one of the parallel windings; transformers in which the magnetism and induced secondary voltage increases, decreases or goes through zero with time, as explained later herein; a slow transformer with a resistor in serieswith one or both paralleled windings within the paralleled connection as shown in the drawing, the resistors, where there are two being differentially heated by the currents therein or cooled differentially by any well-known method o'f radiation, convection, conduction or diffusion of heat; resistors or paralleled windings having the same temperature coeicients of resistance, either. positive or negative; slow transformers which are sub-- stantially silent in operation when there is substantially no magnetism present but which produce a sound of varying i-ntensity corresponding to the change in net magnetism produced by the parallel windings; and any other means for producing a slow transformer within the scope of the appended claims.

A still further object of my present invention is to apply the structure described, and producing the slow transformer effect, to any commercially known type transformer. There are many well known types, such as three-phase transformers, auto-transformers, current and voltage transformers, induction regulating transformers, constant current transformers and others. For

simplicity, only a single phase transformer will be illustrated and described, but it is to be understood that the structure may be applied in any of the types known in which it may be useful.

Other and further objects of my invention are set forth more fully in the specification hereinafter following by reference to the accompanying drawing, in which:

Figure 1 diagrammatically shows one form of slow transformer embodying my invention; Fig. 2 illustrates a 'modified form of slow transformer embodying my invention; Fig. 3 shows an arrangement of slow transformer in which paralleled windings are employed in an assisting relation; Fig. 4 diagrammatically illustrates a slow transformer in which paralleled windings are employed in opposing relation; Fig. 5 discloses a slow transformer embodying my invention and having a movable core memberassociated therewith; Fig. 6 diagrammatically illustrates a circuit for a slow transformer employing series rei sistors in circuit with the windings; Fig. 'I shows a modified circuit arrangement for a slow transformer embodying my invention. l

In the slow transformer of my invention, two inductively coupled windings Iare connected in parallel. They may be the primary coil or the secondary coil of the transformer. This is shown in Fig. l1 where windings 3 and ll are in parallel, and act by electromagnetic induction through core 5 on winding 5. The supply may be brought in at l-l and the load connected to 2 2, or vice-versa. In Fig. 2, both primary and secondary coils consist of two parallel and inductively coupled windings. These are'shown at 1 and 8 and act through core 9. The operation of slow electromagnetic devices employing two paralleledinductively coupled windings has been explained in the patent applications given above. A brief explanation is given below:-

Consider first the paralleled windings connected to oppose one another magnetically. 1f the magnetomotive force produced by each is the same and there is complete ux interlinkage, no magnetism will be produced. There will be no self-induction of one turn on the next, no mutual induction between one winding and the other and no electromagnetic induction from a primary winding into a secondary. With no magnetism, there is no vibration or sound, no eddy current or hysteresis losses. The power f-actor of the device as a whole is 100%.

If now, with current maintained in the circuit, the resistances of the parallel paths are caused to change disproportionately, for instance, if one increases while the other remains constant or decreases, the currents in the parallel paths will change disproportionately, upset the magnetomotive force balance and set up magnetism, the intensity of the magnetization depending on the amount of unbalance. All of the effects of magnetism,l stated above as absent, will now appear. The time element will be the time it takes for the resistances in the parallel paths to change, which in the devices disclosed herein is a function of the temperature attained by them, whether the resistances be those of the windings themselves or resistors in series therewith within the parallel connection.

The electrical action is complex, with magnetism present, but the net result is that the currents tend to divide in the inverse ratio of the turns in the paralleled windings biased by the resistance of the paralleled circuits. If the resistance of one parallel path is increased, the magnetomotive force produced by the winding in that path decreases, and the other winding is, in effect, strengthened. This continues until, with infinite resistance (open circuit) in one path, the other develops the maximum possible magnetomotive force and carries the full line current.

The windings need not have equal magnetomotive forces initially. Assume winding 3, Fig. 1, stronger than winding 4 when they are first energized. Assume the heating conditions such that winding 3 gets hot while winding 4 stays cool. Winding 3 will increase in resistance,-assuming lit has a positive temperature coeicient of resistance,-will lose in current and magnetomotive force, and if the action continues, will reach a condition at which winding 3 and winding 4 will equalize magnetically and all magnetism in core 6 will have disappeared.

If the action is continued further, winding 3 will continue to weaken, and now winding 4 will predominate and set up the flux in core B. The instantaneous polarity of this flux will be the reverse of that produced when winding 3 was producing it and the secondary voltage produced in winding 5 will go through the cycle of falling from a maximum to zero in one instantaneous direction and then rising to a maximum in the opposite instantaneous direction.

It will be understood from the statement above, that a slow transformer may produce a secondary voltage by electromagnetic induction which (1) starts at zero and rises to a maximum or (2) starts at a maximum and falls to zero or (3) starts high with one instantaneous polarity, falls to zero, and rises again with the oppositeinstantaneous polarity,

By altering the heating cycle, other cyclic changes in secondary voltage may be produced automatically over a time period.. If, for instance, when current is first supplied, one windtime of production.

until the temperatures are equal, the original change in magnetism caused by the disproportionate change in resistance will be nullified and the magnetism will have returned to its original value, whether a high value or zero. By compounding thev effects of heat diffusion with the type of coil which goes from one value through zero to another value, it is possible to introduce further automatic ondary voltage of a slow transformer.

Circulating current in the local circuit produced when two inductively coupled windings are connected in parallel is a factor in th'e time element of a slow transformer. 'This circulating current, a product of mutual induction, is present whenever the voltage set up by induction in one winding of the pair differs in intensity from the voltage set up in the other winding. The effect is that the sum of the currents in the parallel paths is greater than the line current, and since heating is determined by current value, and th'e ampere turns control the magnetomotive force, it will be seen that circulating current is an important factor in the design of slow transformers and affects the secondary voltage in value and in K Where in the claims I refer to the effects of electromagnetic induction" it is to be understood that I refer to any or all of the effects of self-induction, mutual induction, including circulating current, and the induction from one winding into another with no ele ,rical connection therebetween.

In my copending application Serial No'. 671,- 767, of which this application is a continuationin-part, I disclose the use of the same temperature coefficient of resistance materials in the paralleled windings, and obtain the disproportionate change in resistance in these windings by disproportionate temperature changes in the windings. Figs. 1, 2, illustrating this arrangement.

Various means for producing differential heating of the paralleled windings are. explained therein and will be repeated here. One means for producing a higher temperature in one coil than in the other consists in putting more turns in` one paralleled winding than in the other. If the leakage flux between the paralleled windings is zero there will be no net magnetism, assuming the conductions forming the windings have the same cross section, same material and same resistance per turn, since the lesser turns of one will be made up for by the larger current therein. But the larger current in the few turn winding will heat that winding to a higher temperature and increase its resistance more than the many turn winding, upsetting the current split between the paralleled windings, and changing the magnetism and induced secondary voltage. As magnetism in the core increases it accentuates this heating by tending to hold the currents in the paralleled windings in the inverse turn ratio biased by the resistance. A relatively large change in resistance is required to pull the currents out of inverse turn ratio, with the net result that the heating of the fewer turn winding progresses at an accelerated rate as its resistance rises.

Using a different number of turns in the two paralleled windings is, therefore, an effective means for producing differential heating therein, even though the windings be of the same material, the conductors of the same cross section and cyclic variations in the sec-` 3, 4, 6 and 7 may be taken as Y initial resistance per turn and with substantially complete flux interlinkage between paralleled windings.

A second means of insuring that one coil rises to a higher temperature than the other consists in making the initial resistances of the windings unequal with equal turns. A greater percentage of the total current will pass through the lower resistance winding and their heating will be unequal. This can be accomplished in at least three ways:

1. By varying the relative cross-section of the conductor in the windings, with the same material-in each;

2. By using different materials having substantially equal temperature coefficients of resistance, but one of the materials having a higher specific resistance than the other;

3. By making the length of mean turn of one winding different from that of the other, using the same size and kind of conductor in each.

In Figs. V6 and 7 are shown alternate methods for producing slow magnetism in a transformer. In Fig. 6, windings I and I I are the paralleled primary windings, while I2 is the secondary, all inductively coupled through core I3. Two resistors I 4 and I5 are connected in series with windings I 0 and II respectively. The winding II are less than the turns of winding I0. With magnetism in core I3, the currents in these windings will tend to change -to the inverse turn ratio, a larger current traversing circuit II-I5 and a lesser current circuit I0-I4. If resistors Iii-I5 have the same temperature coefcient of resistance and are, when cold, equal in resistance, the greater current in I5 will heat it faster than I4 and bias the currents away from the inverse turn ratio toward the inverse resistance ratio. The unequal heating of resistors I4 and I5, therefore, results in a change in themagnetism threading core I3 and secondary winding I2 and affects the voltage across winding I2. A slow transformer has, therefore, been shown in which the element producing the change with time is embodied in resistors where the resistors have the same temperature coefficient. This coefficient may be positive or negative and may be zero if the line current is altered cyclically by other means.

In Fig. '7, resistor I5 is omitted and resistor I 4 has the same temperature coefficient of resistance as windings I 0 and II. Here, the change is all due to the variation in temperature in resistor I4, but the effect is produced without the use of dissimilar temperature coeicient of resistance materials.

In Fig. 5, a slow transformer is illustrated in which part of the core is movable to introduce air gaps of Varying amounts in the magnetic circuit. Here, windings I6 and I1 are the paralleled primaries, while I8 is the secondary. Core I9 has a. movable portion 20 biased in the direction of arrow 2| by gravity, a spring, or other means. Windings I6 and I'I have the same turns and are connected to oppose one another magnetically, but winding I 6 is of lower initial resistance than I1 and, therefore, II will heat more in proportion, and its resistance will rise more rapidly than I6. I have indicated winding IG in heavier line than winding I'I to designate the lower resistance in winding I6.

When core 20 is down, air gaps 22-23 keep the magnetism at a low value, and the flux threading IS-I 'I may be assumed insufficient to appreciably affect the current values therein.

' this occurs tends strongly to pull the currents in |6-l1 into a 1 to 1 ratio, since the turns are equal. Thus, a larger percentage of the total current flows through l than before the core moved, accelerating the heating of this winding. The effect is cumulative, the disproportionate increase in resistance raising the flux density and the increase in magnetism accelerating the resistance rise. The changes in magnetism in core I9-20 result in a relatively slow rise in voltage in Winding i8 until core piece 20 moves, at which time there is a rapid increase in voltage in winding I8, and after that the relatively slow rise, due to the windings heating, is resumed.

If windings IB-ll, Fig. 5, are of thetype which start with maximum magnetism and decrease With time, the core piece 20 will be instantly attracted when the transformer is energized, and then the magnetism will begin to decrease, relatively slowly, dropping the secondary voltage slowly until the holding force of the magnet-ism is less than the bias El, when the core piece 20 will move, opening air gaps 22-23 and rapidly dropping the magnetism and secondary voltage to a low or zero value.

As has been explained above, the more magnetism there is linking with the paralleled windings the greater is the effect, common in transformers, of tending to hold the currents in the paralleled paths in their inverse turn ratio. Since the current split in these windings directly influences their heating, the action of the movable core in increasing or decreasing the reluctance of the magnetic circuit changes the magnetism therein and thus inuences vthe current split, heating and resistances of the paralleled windings.

The paralleled windings of Fig. 5 may be connected to assist one another magnetically as in Fig. 3 or to oppose as in Fig. 4.

In applic-ation Serial No. 705,466, of which this application is a continuation-impart, various electro-magnetic devices are disclosed. using a pair of paralleled inductively coupled windings connected to assist one another magnetically.l

This is useful in a slow transformer where it is not necessary for the magnetism set up by the windings to fall to Zero with current in the windings. In Fig. 3, windings 2li-25 and 26 are all inductively coupled through core 21 and 24-25 are connected to assist, as in dicated by the N-S markings, meaning north and south pole, respectively.

In Fig. 4, windings 28-29 and 3E! are inductively coupled through core 3| and are connected in opposition as indicated by the N-S markings.

The 4assist connection of Fig. 3 is more effective in producing a large change in magnetism for a given change in resistance, since there is no subtr'active magnetic action, whereas the opposed connection of Fig-4 is essential where it is necessary for the net magnetism to fall to zero, at any point of operation with current in the windings. In Fig. 2, the arrangement of the parallel connected windings 'l and 8 is such that the windings magnetically assist each other. In certain cases, I may employ the parallel connected windings in magnetic opposition. Fig. 8 shows the arrangement of windings in magnetic opposition.

The parallel connected primary windings are` shown at l0 and Il connected in opposition. The

other than may be imposed by the scope of the appended claims.

What I claim as new and desire to secure by Letters Patent of the United States is as follows:

1. A slow transformer including a primary and a secondary coil, at least one of said coils constituted by a pair of inductively coupled windings connected in parallel one with respect to the other, and mcansto produce disproportionate resistance changes with temperature changes therein, to alter the effects of electro-magnetic induction in said transformer.

2. A slow transformer including a primary and a secondary coil, at least one of said coils constituted by a pair of inductively coupled Windings connected in parallel one with respect to the other, said parallel paths including only thenecessary connections and said windings, and means to produce disproportionate resistance changes with temperature changes in said windings, to alter the effects of' electromagnetic induction in said transformer.

3. A slow transformer including a primary coil and a secondary coil, at least one -of said coils constituted by a pair of inductively coupled windings connected in parallel one with respect to the other, at least one of said windings having a resistor in series with it within the parallel connection, means to produce disproportionate resistance changes in said parallel paths with temperature changes in said resistor, to alter the effects of electromagnetic induction in said transformer.

4. A slow transformer including a primary and a secondary coil, at least one of said coils constituted by a pair of inductively coupled windings connected in parallel one with respect to the other, said parallel paths including only materials having substantially the same temperature coefficient of resistance other than Zero, means to produce disproportionate resistance changes with temperature changes in said parallel paths, to alter the effects of electromagnetic induction in said transformer.

5. A slow transformer including aprimary and a secondary coil, at least one of said coils constituted by a pair of inductively coupled windings connected in parallel one with respect to the other, said parallel paths including only said windings and the necessary connections, said windings formed of materials having substantially the same temperature coefficient of resistance other than zero, and means to produce disproportionate resistance changes with temperature in said windings to alter the effects of electromagnetic induction in said transformer.

6. A slo-w transformer including a primary G temperature in said series resistors, to alter the eiects of electromagnetic induction in said transformer.

'7. A slow transformer having primary and secondary coils, at least one of said coils comprising a pair of inductively coupled differential windings connected in parallel one with respect to the other, said windings formed of materials having substantially equal temperature coefcients of resistance other than zero, and means for causing said'windings to operate at different temperatures in coaction with one another, to alter the eiects of electromagnetic induction in said transformer.

8. A ,slow transformer having primary and secondary coils, at least one of said coils comprising a pair of inductively coupled windings arranged to oppose one another and connected in parallel one with respect to the other, said windings formed of materials having substantially equal temperature coeillcients of resistance other than zero, and means for causing said windings to operate at different temperatures in coaction with one another, to alter'the e'ects of electromagnetic induction in said transformer.

9. A slow transformer having primary and secondary coils, at least one of said coils comprising a pair of inductively coupled windings arranged to assist one another and connected in parallel one with respect to the other, said windings formed of materials having substantially equal temperature coeilcients of resistance other than zero, and means for causing said windings to operate at different temperatures in coaction with one another, to alter the effects of electromagnetic induction in said transformer.

10. A transformer having a primary coil and a secondary coil, one of said coils comprising a 5 pair of inductively coupled windings disposed in parallel one with respect to the other, means to produce disproportionate changes in the resistance of the windings with temperature changes, said windings coacting to produce substantially ux interlinkage.

1l. A transformer having a primary coil and a secondary coil, one of said coils comprising a pair of inductively coupled windings connected to assist one another magnetically disposed in parallel one with respect to the other, said windings being formed of materials having substantially diierent temperature coeilcients of resistance.

12. A slow transformer including a primary and a secondary coil, at least one of Ysaid coils constituted by a pair of inductively coupled windings connected in parallel one with respect to the other, said windings mounted on a core having a movable portion, means to produce disproportionate resistance changes with temperature in said parallel paths, said resistance changes and the changes in magnetism resulting from movement of said movable core portion cooperating to alter the effects of electromagnetic induction in said transformer.

13. A slow transformer including a primary and a secondary coil, at least one of said coils constituted by a pair of inductively coupled windings connected in parallel 4one with respect to the other, a resistor in series with each winding within the parallel connection, said resistors formed of materials having substantially the same temperature coeilcient of resistance other than zero, and means to disproportionately change the resistance of said resistors by disproportionate temperature changes therein, to alter the effects of electromagnetic induction in said transformer.

ALBERT B. RYPINSKI.

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