US2140553A - Slow electromagnetic device having the same temperature coefficient of resistance materials in assisting windings - Google Patents

Description

Dec. 20, 1938.

A, B RYPINSKI HAVING THESAME TEMPERATURE CoEF E l E1".- l

original Filed May 18, 1933 SLOW ELECTROMAGNETIC DEVICE Patented Dec. 20, 1938 ,nosas y lE'ENT FMC?.

SLOW ELECTROMAGNETIC DEVICE HAVING THE SAME TEMPERATURE COEFFICIENT F RESISTANCE MATERIALS IN ASSIST- ING WINDINGS Albert B. Rypinski, Laurelton, Long Island, N. Y.

Original application May 18, 1933, Serial No.

671,767. Divided and this application January 5, 1934,- Serial No. 705,466

13 Claims.

My invention relates broadly to slow electromagnets, reactors and transformers and particularly to structures thereof employing the same temperature coelicient of resistance materials in assisting windings of the devices.

This application isk va division of -application Serial No. 671,767, led May 18, 1933, `-for Slow electromagnets having the same or similar temperature Lcoeiilcients of resistance materials in u) diierential windings now Patent 2,093,368, granted September 14,y 1937, in which I disclose electromagnets, reactors, and transformers employing the same temperature coeiiicients of resistance in the conductors of the slow coil.

My present invention is directed to a slow electromagnet having windings constituted by materials having the same temperature coeiiicient oi resistance and in which the windings assist one another magnetically.'

My present invention is directed to slow electromagnetic devices having windings connected to assist one another magnetically, except as claimed in Patent 2,093,368, supra, and other applications and patents to be cited herein.

lbeen incorporated in Aapplication Serial No. 8,913, filed March 1, 1935, entitled Slow transformer, now Patent 2,089,860, granted August 10,

'LL In my copending application Serial No. 416,877, v tiled December 27, 1929, now Patent 2,082,121, granted June l, 1937-, and divisional application thereof, Serial No. 699,617, led November 24, v 1933, I disclose and claim slow devices with two paralleled Vmagnetically coupled and opposed windings, utilizing diierent temperature coemcient materials in each. In my'Patent 1,972,112, granted September 4, 1934, based on application 40 `and claim a slow reactor with two paralleled, magnetically coupled and opposed windings utilizing the same or similar temperature'coefiicient ymaterials ineach.' Other related applications and patents are: application Serial No. 699,616- filed November 24, 1933--for Motor starting systems. Now Patent 2,047,228, dated July 14, 1936. Serial No. 699,618-filed November 2,4, 1933--for motor control system. Now Patent 2,093,368, dated September 14, 1937` Serial No. 699,619- filed November 24, 1933-for Distribution systems. Now Patent 2,082,122, dated June 1, 1937. serial No. 699,620-ii1ed- November 24, 1933--for` Arc welding apparatus. Now Patent 2,009,787, dated 55 July 30, 1935. Serial No. 671,768-filed May 18,

All vrelevant description and claimsvt a slow transformer, originally in this application, have Serial No. 608,095, iiled April 28, 1932, I discloseJ 1933--for Coils for slow electromagnets and reactors. Now Patent 1,972,319, dated September 4, 1934. Serial No. 703,313--1ed December 20, 1933-for Electromagnetic device. Now Patent 2,068,712, dated January 26, 1937.

One of the objects of my-invention is to produce a slow reactor with two paralleled inductively coupled windings connected to assist each other magnetically, employing the same temperature coeiiicient materials in each.

` Another object of my invention is to provide a slow electromagnet employing the same temperature coeiiicients of resistance materials in assisting windings.

As fully described in the patentapplications cited above, the invention may be directed to the production of an electromagnet, a reactor or transformer whose magnetism is caused to change with time and utilized for any purpose to which such a device is suited, such asincreasing or decreasing the current or voltage applied to a load to aiiect the operation of devices connected to the line, or it may be used to alter or hold constant its own power factor, to control a current flowing through it into a load, or for other uses.

Other and further objects of mly invention `reside in the structures and arrangements more fully set forth in the following specification by reference t'o the accompanying drawing, in which: Figure 1 is a schematic diagram showing a pair of paralleled windings connected to assist each other magnetically; Fig. 2 is a sectional View of an electromagnet showing the separate windings comprising my invention; Fig. 3 shows a modication of the electromagnet of Fig. 2 in which y the windings are divided into a number of sections; Fig. 4 is a cross sectional view taken through a modied form of electromagnet embodying the principles of my invention; Fig, 5 is a cross sectional lviewof a further modiedform of electromagnet embodying my invention; and Fig. 6 shows another modified form of slow electromagnet.

In all cases two windings are connected in parallel so that any magnetism and magnetic action produced is the resultant of two magnetomotive forces assisting each other. The value of the magnetomotive force of each winding is determined by its ampere turns and in any given coil by the sum of the ampere turns in the two windings. The current in the windings divides in the inverse ratio of the resistances ofthe windings When supplied with direct current. With magnetism threading the windings on direct current, the' currents divide in the inverse ratio of the resistances, and on alternating current, the currents tend to divide in the inverse ratio ot the turns, biased by the resistances of the windings.

Since the windings are inductively coupled there is the well understood eiiect on alternating current of the currents tending to hold themselves in the inverse ratio of the turns. In addition, and contributing to the same result, there is a circulating current generated by one winding and circulating through both, whenever the induced voltages in the` windings are unequal. These effects are results of mutual induction between the inductively coupled windings. When, in the claims, mutual induction between windings is mentioned it is to be understood as including all the above eifects. If the windings are connected to assist each other and if the total current is constant and the turns are equal, a change in resistance in the windings will not aifect the total ampere turns, since what one loses the other gains and their eifects are additive. If the current is not held constant butis allowed to vary as the resistance and inductive reactance oi' the circuit change, and this is usually the case, a pair of assisting windings with the same turns in each will alter their total ampere turns as one winding is heated more than the other due to the increased resistance lowering the line current, and therefore the separate currents in the windings.

If the total current is constant and the turns are unequal a change in the relative resistance of two assisting windings will alter the total ampere turns, because, while the ampereslost by one will equal those gained by the other, the ampere turns lost by the one will necessarily be different from those gained by the other, due toI the inequality of the turns in the windings. Itis thus seen that the magnetism set up by two paralleled windings of unequal turns inductively coupled, and connected to assist each other, will change with variations in the relative resistances or the two windings. j

It is not essential that the materials be of different temperature coeilicients of resistance. If identical materials with a high coeilicient are used, and the one is heated more than the other, the resistance of the hotter conductor will rise more than that of the cooler one, alter the current split between them and consequently change the magnetism of the coil. Using the same coeillcient materials gives rise to advantages not present where radically different coeiilcient materials must be employed. For instance, for temperatures not exceeding its oxidation point, or where the heated wire is not exposed to oxidation, copper may be employed in both windings. It is inexpensive, commercially available in many sizes, and easy to handle. Due to its low specic resistance many more turns of copper can be employed for a given resistance than with other conductors, which is an important advantage in electromagnet design. 'I'he specific resistance of copper is 10.55 ohms per circ. mil. ft. A copper to copper coil maybe more readily constructed than a coil where low coefficient materials, such as one wellknown alloy, with specific' resistance of 675 vohms per circ. mil. foot, are used.

Where the temperatures are below the melting point of aluminum, aluminum and copper may be used, the aluminum for the hotter coil. Aluminum oxidizes but the oxide once formed is a non-conductor, very tough and elastic, so that it does not 'scaleofL For higher temperatures, copper and nickel may be used, the nickel in the hot coil. Nickel does not oxidize as does copper but is more expensive than aluminum or copper. Other metals may be used, depending on physical and commercial considerations.Y

All elementary metals except mercury, have a temperature coeflicient of approximately .004, as shown in the following table, as given on pages 32,3, 3,24y and 325 of the Smithsonian Physical Tables for 1929:

Temp. Temp. Material Temp. coe. oi Material Temp. coed. of

res. res.

0. C. Ial'a Aluminum 25 0034 Advance 'Antimony 20 .(1)36 25 .000002 Bismuth Z) .m4

' Z) .m38 .0036 .00393 20 .0007 20 .0004 0052 20 00016 Lead.. I) .0039 Magnesium. 1) .0040 German silver 20 0004 Mercury 20 .00089 Molybde- 25 .0033 M 25 z Nll 25 0043 all alllll l'O g Palladium Z) .0033 Monel metal 20 .00%) Platinum- Z) .003

Silver Il (m8 Therlo 20 .00001 Tantaluun-- 20 K. 0031 Tin m .0042 .Tungsten 18 .0045 Zinc 20 .0037

It will be noted that the alloys are generally of lower coetlcient than solid. metals. In the claims where I specify materials of equal or substantially equal temperature coefilcients, it is to be understood that all elementary metals except mercury are substantially equal to each other. but the s'olid elementary metals are not substantially equal to the alloys.

Coupled with the use of equal or substantially equal materials is the inherent necessity for producing a higher temperature in one conductor than in the other in order to produce a change in magnetism with time. 'I'here are many means of accomplishing this and while I have connned the illustrations to only a few of the forms which .the slow electromagnet oi my invention may assume, I desire that it be understood that in illustrating my invention in the several forms shown that I do not intend such illustrations to be interpreted in the limiting sense.

The windings may be wound on in alternate layers or arranged as alternate pancakes side by side or in any other suitable manner. A coll may contain more than two windings but in all cases the windings will form the equivalent of two groups in parallelinductively coupled, thetotal net magnetism produced varying with the heating of the windings.

It is well known that an increase in the inductive reactance of an alternating current coil lowers its power factor, while an increase in its resistance raises its power factor. By constructing a slow electromagnetic device'of the type disclosed herein of properly proportioned materials,

the increase in inductive reactance and the cor' Y responding increase in resistance may be made to result in a substantially constant power factor. This is of advantage for coils operating in circuits where it is undesirable to lower the power factor when the magnetism of the coil is increased.

Referring to the drawing in detail, Fig. 1 shows the connection of two paralleled windings I and 2 arranged to draw current from a pair of lines I, both supported on the same core 3.- Connected as shown, their magnetic ei'Iect on the core will be additive as indicated by the N and S markings, north and south poles, respectively.

Fig. 2is asectional View of an electromagnet in. which the windings i and 2 are placed side by side on the core 3. Armature 3a is movably mounted for magnetic coaction with the pole pieces of the core 3. Heat conducting or insulating material I4 and air space l are disposed about thewindings to control the heating thereof.

Fig. 3 is a sectional view of a modified form of the electromagnet shown in Fig. 2. The windings I and 2 are formed in two sections each and Vmounted alternately on the core structure 3.

Heat conducting or insulating material Il, air

spaces 1, and amature 3a are provided as shown in Fig.2.

The term leakage reactance is used to measure the leakage magnetism in a two coil transformer or other magnetic device, that is, the magnetism originating in one coil but not linking with the other. In slow electromagnets or reactors it is important to keep this leakage at a low value. l

Fig. 4 shows an arrangement consisting in having the cooler winding I of copper adjacent the core 3 and wound and insulated asis common for electromagnets of the usual type. The carrying capacity of the conductor is made suilicient to insure its operation at the accepted temperature rise for electromagnets. The opposing winding 2 designed for higher temperature operation is wound over the other with suitable air spaces or heat insulation or both, or any other means to prevent the heat soaking through into the cool coil and to insure proper heat dissipation from both coils. Assume both coils of the same coefficient material and of )the same specific resistance (copper to copper, for instance), and also assume the conductors of the same cross sections and total resistance. On direct current and on alternating current when balanced magnetically,

the currents in each of the windings will bev equal. The energy expended in each winding will be equal. The heat is measured by the watt loss and the windings would rise to equal temperatures if al1 other factors were equal.

. sisted by the fact that the thermal conductivity' of air is lower than that of practically all solid materials. Surrounding one winding with solid material of relatively good conductivity and large radiating surface While the other is mainly in contact with air is a practical means for producing a higher temperature in the winding surrounded by airproviding the cooling veiect of air circulation is controlled in the design. Where design conditions require it, the air space 25 may be vented to the outside air or in extreme cases, aforced draft of air may be introduced to keep winding I at a low temperature while winding 2 rises to a. higherv temperature.

I have indicated openings or vents 22a and 23a in headers 22 and 23, respectively, through which a cooling current of air may pass between the rows of turns of the winding I. The arrows and the legends indicate the passage of the air from aisance the outside of the coil to winding I and out again.

AA more pronounced dlderence results if the resistance of the two windings is changed by altering the turns, putting more on the inner coil and less on the outer coil, as illustrated in Fig. 5, leaving the materials and the wire sizes equal as before.

Another means of producing a higher temperature in one coil than in the other is by altering the ratio of the turns, `that is, putting more turns on the inner coil and less on the outer coil, as shown in Fig. 6.

If the total resistance and line current remain the same as before, the inner coil will have less in the inner winding, using the same material as before (copper to copper, for instance). Extra turns will need to be added to the inner coil or turns removed fromthe outer coil to insure that the light wire gets enough current to insure its heating.

It is to berunderstood that the various means disclosed for altering the relative heating of the windings 'are not confined toA the design shown in Fig, 4, but apply to any other arrangement \withln the scope of the invention. (I may vary the varrangement from that described above in various ways. In Fig. 6, the hot winding 2 is 1ocated adjacent the core and may be with or without an air space 'l between the winding and the core.

It is to be understood that the foregoing de- Y scriptions of modifications of my invention apply equally well to electromagnets, reactors an transformers. I While I have described my invention in certain preferred embodiments. I desire that it be understood that modification may be made and no limitations upon my invention are intended 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:

l. A slow electromagnetic device comprising a pair of inductively coupled windings connected in parallel one with respect to the other so that the polarity of the magnetism produced by one winding is such as tobe additive to the magnetism produced by the other winding, said.

windings havin( different` numbers of turns and being 'constituted by materials having the same temperature coefhcients of resistance, said materials constituting means, when energized and heated, to substantially and disproportionately alter the resistance of said paralleled windings and the sum total of magnetism of said device, said different numbers of turns constituting means, through the transformer action between said inductively coupled windings, to further alter the division of current in said two windings and the magnetism of said device.

2. A slow electromagnetic devicer for connection in series with a supply line and a .load comprising a pair of inductively coupled windings u connected in parallel one with respect to the other so that the polarity of the magnetism produced by one winding is such as to be additive to the magnetism producd by the other winding, said windings having different numbers of turns and being constituted by materials having the same temperature coefficients of resistance, the fewer turn winding having a greater resistance than the other when both said windings are at ambient temperature, said materials constituting means, when heated, to disproportionately alter the resistance of said paralleled windings to a substantial extent and the sum total of magnetism of said device, said different numbers of turns constituting means, through the transformer action between said inductively coupled windings, for causing the currents in said windings to divide in the inverse ratio of their turns, biased by the resistances thereof, to further alter the division of current in said two windings, the higher resistance of said fewer turn windings serving to accelerate the heating thereof when traversed by the current maintained therein partly by said transformer action.

3. A slow electromagnetic device for connection to a direct or alternating current supply cornprising -a pair of inductively coupled windings connected in parallel one with respect to the other so that the polarity of the magnetism produced by one winding is such as to be additive to the magnetism produced by the other winding, said windings having different numbers of turns and being constituted by materials having the same temperature coefficients of resistance, said fewer turn winding having a greater resistance than the other when both windings are at ambientl temperature, said device functioning differently as to the production of slow magnetism on direct current than on alternating current, the currents in said paralleled windings dividing in the inverse ratio of the resistances on direct current and in the inverse ratio of the turns of said windings biased kby their resistance on alternating current, the substantial disproportionate heating of said windings and substantial disproportionate changes in temperature therein over a time cycle constituting means to produce effective changes in magnetism.

4. A slow electromagnetic device as in claim 3 except that the fewer turn winding has resistance equal to the other when both windings are Aat ambient temperature.

5. A slow electromagnetic device as in claim 3 except that the fewer turn winding has a lower resistance than the other when both windings are at ambient temperature.

6. An alternating current slow electromagnetic device comprising a pair of inductively coupled windings connected in parallel one with respect to the other to form parallel paths, so that the polarity of the magnetism -produced by one winding-is such as to be additive to the magnetism produced by the other winding, said parallel paths including only materials having substantially equal temperature coemcients of resistance other ture changes therein, to alter the magnetism of said device.

7. An alternating current slow electromagnetic device comprising a pair of inductively coupled greater resistance than the other when both said 1l windings are at ambient temperature, said.dif ferent numbers of turns constituting means, through the effects of mutual induction between said windings, for causing thevcurrents in said windings to divide in the inverse ratio of their l turns, biased by the resistances thereof, to alter the division of current in said two paths by the disproportionate and substantial changes in resistance thereof over a time cycle, the higher resistance of said fewer turn winding serving to 2 accelerate the heating thereof when traversed by the current maintained therein partly by said mutual induction effect.

8. A slow electromagnetic device for connection to a direct or alternating -current supply 2 comprising a pair of inductively coupled windings connected in parallel one with respect to the other to form parallelled windings so that the polarity of the magnetism produced by one winding is such as to be additive to the magnetism pro- 3 duced by the other winding, said windings being formed of materials having substantially equal temperature coefficients of resistance and having different numbers of turns, said diderent numbers of turns constituting means for causing S substantial disproportionate changes in resistance with substantial disproportionate temperature changes in said windings, said device functioning differently as tothe production of slow magnetism on direct current than on alternating 4 current, the currents in said paralleled windings dividing in the inverse ratio of the resistances on direct current and in the inverse ratio of the turns of said windings biased by their resistances on alternating current. f '4 9. An electromagnetic device comprising a pai of inductively coupled windings having substantially the same temperature coefllcients of resistance and connected in parallel one with respect to the other so that the polarity of the 5 magnetism produced by one winding is such as to be additive to the magnetism produced by the other winding, the relative resistances of said windings proportioned to produce disproportionate heating and disproportionate resistance 5 changes therein when energized, heat insulation between windings to permit partial heat diffusion from the hotter to the cooler winding, said heat insulation being proportioned to permit substan- 4tial temperature equalization between windings 6 until the total current in said windings exceeds a predetermined critical maximum above which the heat -iiow through said insulation is insumcient to balance the temperatures, currents greater than said critical maximum serving to produce il disproportionate changes in resistance in said windings to alter the magnetism of said device.

10. An electromagnetic device comprising a pair of inductively coupled windings having substantially the same temperature coefilcients of resist- '1 ance and connected in parallel one with respect to the other so that the polarity of the magnetism produced by one winding is such as to be additive to the magnetism produced by the other winding, the relative resistances oi said windings being 7 proportioned to produce disproportionate heating and disproportionate resistance changes therein when energized, heat insulation between windings to permit partial heat diffusion from the hotter to the cooler winding, said heat insulation being proportioned to prevent temperature equalization between windings until a predetermined temperature diierence has been maintained for a predetermined time, temperature equalization at the end of 'said time serving to substantially nullify said disproportionate temperature and resistance change and restore initial magneticI conditions.

11. A constant power factor slow electromagnetic device comprising a pair of inductively coupled windings, said windings being connected in' parallel one with respect to the other so that the polarity of the magnetism produced by one winding .isf such as to be additive to the magnetism produced by the other winding, said windings being formed of materials having substantially the same temperature coeicients of resistance other than zero, means for disproportionately heating said windings, the relative magnetomotive forces of said windings being proportioned so that the net inductive reactance of said device increases as the resistance increases, to result in a substantially constant power factor with changing magnetism.

12. An electromagnetic device as in claim 8 in which the means for causing substantial disproportionate temperature changes in said windings include differential. heat dissipating means associated with the windings whereby with equal amounts of energy liberated in the two windings, said windings will rise disproportionately in temperature.

' 13. An electromagnetic device as in claim 8 in which the means for causing disproportionate temperature changes in said windings comprises differential heat dissipating means, allowing dissipation from one winding within limits of .5 watt per square inch under maximum load conditions, and dissipation from the other winding within limits of '7 watts per square inch under maximumv load conditions. f

ALBERT B. RYPINSKI.

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