US1626691A - Resistor alloy - Google Patents

Description

May 3, 1927. 1,626,691

. N. a. FILLING RESISTOR I ALLOY Filed sep'L. 2, 1922 Mck/ Capper Alloy CantaininyMaynes/m WITNESSES: I INVENTOR ATTORNEY Patented May 3, 1927.

UNI ED STATES PATENT OFFICE.

NORMAN B. FILLING, OF WILKINSBURG, PENNSYLVANIA, ASSIGNOR TO TESTING- HOUSE ELECTRIC AND MAN UFACTURING- COMPANY, A CORPORATION OF IPIEIWISTSYL-- VANIA.

nnsrs'ron ALLOY.

4 Application filed September '2, 1922. Serial No. 585,855.

This invention relates to alloys, more particularly to alloys capable of utllization as electrical resistance materials and characterized by a negative temperature coeflicient of resistance.

Alloys of this type, I have found, are

especially adapted for use in measuring instruments of a delicate nature, such as meters and the like. A meter, as generally constructed, comprises a permanent magnet between the poles of which is a rotatable copper coil, the terminals of which are connected into a suitable circuit to be ,easured. A helical spring is secured to the copper coil, the force of said springopposing-the deflection of the copper coil, which is proportional to the current flowing through it.

Changes in temperature cause unequal,

changes in these elements. 6

The effect of a rise of temperature upon the elasticity of the spring and the strength of the magnet is a tendency to allow the copper coil to increase its deflection upon the passage of current therethrough. This tendency to increase the deflection has been balanced to some extent by placing in series therewith a suflicient amount of resistance having a low temperature coeflicient of resistance of the entire circuit approximately equal to the temperature coefliciont of the balancing resistance. Up to this time, wire having approximately zero temperature coefficient was used.

I I have inserted, in place of. the zerotemperature-coeflicient wire previously used, a wire having a negative temperature coeflicient, such that it balances the variations caused by the other elements of the meter. By reason of the use of such a resistor, the compensation for thetemperature effect of the other elements may be effected with a considerably smaller amount of resistance, so that the measuring instrument becomes more sensitive.

In carrying my invention into effect provide an allo 'of\ copper and nickel which possesses, at or inary room temperature and above, a negative temperature coeflicient of resistance which may be utilized for various compensation purposes, such as in electrical systems, the total resistance of which is to be maintained constant, irrespective of .changes in temperature. More specifically, I have found that such alloys having fromto of nickel and containing a small amount of magnesium in the composit1on thereof are most effective for this purpose.- I

The addition of magnesium also facilitates the workability of thealloy. I have found that as little as 0.1% of magnesium is suflicient for this purpose and I-prefer not to add a materially greater amount, since larger amounts tend to make the material more diflicult to 'work.

I am enabled to utilize ordinary technical nickel in* my invention since the small amounts of iron and cobalt therein do not interfere with the development of the desirable propertiesof my new alloy. In the accompanying drawing, constitutmg a part hereof, the single figure is a diagrammatic view of a meter embodying the subject matter of my invention.

A permanent magnet '1 has, between the poles 2 and 3 thereof, a core 4 fixed on a shaft 5 and a copper coil 6 is secured to said core. A helical spring 7 has its inner end secured to the shaft 5 and its outer end to a fixed point of the meter. Leads 8 and 9 are secured to the spring and one end of the copper com-respectively, and a resistor 10 of my new allo placed in series with said copper coil. T e leads 8 and 9 may beconnected, in a suitable electrical circuit, the characteristics of which are to be measured.

Although I have found thatthe proportions of ingredients of my new alloy may be varied withincertain limits, I have found loy may be used. Such a temperature is never attained in commercial measuring instruments. The coefficient is still negative at temperatures approaching that of llqllld. air.

I have prepared a number of alloys of different compositions, 511 of which have negative temperature coeflicients and of which the following are typical:

Per cent. Per cent.

, Copper 60.23 50.07 'Nickel 39.70 49.85- Magnesium. 0.1 0.1 Specific elec; resist. at q 20 C. microhm cm. 45.7 51.8

' Temperature coefi'Q:

At 20 C .000047 --.000082 At 400 C -.o00155 .000134 The temperature coefiicients of my new a1- loys vary from approximately '.00005 to .00016. The thermal electro-motive force thereof to copper is approximately the same asthat of the zero tein erature coefficient materiaL hitherto used. y new alloys solder very readily with \soft solder and hard sollder' may be used thereon with good resu ts.

Although I have described my invention stating that a composition of 50% nickel and 50% copper is a preferable one, it should Y be understoodthat my invention is not limited to this specific comg losition. The value of the temperature coe cient for a givenrange of temperature may be adjusted by changing the composition of the alloy, and

my invention contemplates such changes for uses requiring various temperature coefiicients.

I claim as my invention:

1. A resistance alloy consisting of equal parts of nickel and copper and about 1% of magnesium,

2. A resistance alloy consisting of 35 to parts of nickel, to 45 parts of copper and magnesium in amount from a trace to 1%, said alloy having a negative temperature. coeflicient of resistance.

3. A resistance alloy consisting of about equal parts of nickel and copper and a' substantial amount of magnesium in amount from a trace to 1%; said alloy having a negative temperature coefiicientof resistance.

In testimony whereof, I have hereunto sugs cribed my name this 17th day of August, 19 2.

NORMAN B. IPILLING.

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