ASTM B114-07(2013)
(Test Method)Standard Test Method for Temperature-Resistance Constants of Sheet Materials for Shunts and Precision Resistors
Standard Test Method for Temperature-Resistance Constants of Sheet Materials for Shunts and Precision Resistors
SIGNIFICANCE AND USE
3.1 This test method covers the determination of the change of resistance with temperature for precision resistors and shunts made from sheet materials.
3.2 Materials normally used in the temperature range from 0 to 80°C may be tested using this test method.
SCOPE
1.1 This test method covers the determination of the change of resistance with temperature of sheet materials used for shunts and precision resistors for electrical apparatus. It is applicable to materials normally used in the temperature range of from 0 to 80°C.
1.2 The values stated in inch-pound units are to be regarded as the standard. The metric equivalents of inch-pound units may be approximate.
1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to become familiar with all hazards including those identified in the appropriate Material Safety Data Sheet (MSDS) for this product/material as provided by the manufacturer, to establish appropriate safety and health practices, and determine the applicability of regulatory limitations prior to use.
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NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
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Designation: B114 − 07 (Reapproved 2013)
Standard Test Method for
Temperature-Resistance Constants of Sheet Materials for
Shunts and Precision Resistors
This standard is issued under the fixed designation B114; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope 4. Test Specimen
1.1 Thistestmethodcoversthedeterminationofthechange 4.1 The test specimen shall be of such dimensions that its
of resistance with temperature of sheet materials used for electrical resistance can be measured to the required accuracy.
shunts and precision resistors for electrical apparatus. It is
NOTE 1—Measurements are simplified if the specimen has a resistance
applicable to materials normally used in the temperature range
of 0.01 Ω or more. The specimen may be bent in the form of a “U” to
of from 0 to 80°C.
facilitate handling.
1.2 The values stated in inch-pound units are to be regarded
5. Terminals
as the standard. The metric equivalents of inch-pound units
may be approximate. 5.1 A current terminal shall be attached to each end of the
specimen. These terminals shall be either soldered or clamped
1.3 This standard does not purport to address all of the
in such a manner that there will be no change of current
safety concerns, if any, associated with its use. It is the
distribution in the specimen during the test.
responsibility of the user of this standard to become familiar
with all hazards including those identified in the appropriate
5.2 Potential terminals, one at each end, shall be located at
Material Safety Data Sheet (MSDS) for this product/material
a distance not less than two times the width of the specimen
as provided by the manufacturer, to establish appropriate
fromthecurrentterminals.Theseterminalsshallbeattachedat
safety and health practices, and determine the applicability of
the center of the width of the specimen either by soldering to
regulatory limitations prior to use.
ears cut out of the specimen (Note 2) as shown in Fig. 1 or by
clamps, each of which presses a single sharp point into the
2. Referenced Documents
material.
2.1 ASTM Standards:
NOTE 2—The ears shall be cut so that they are about ⁄2 in. (12.7 mm)
B84Test Method for Temperature-Resistance Constants of
inlengthand ⁄8in.(3.2mm)inwidth.Thecutshallbecleanandfreefrom
Alloy Wires for Precision Resistors
sliversatthejunctionoftheearandthespecimen.Beforecuttingtheears,
it is desirable to drill two small holes with a sharp drill where the ear will
3. Significance and Use
be jointed to the specimen.
3.1 Thistestmethodcoversthedeterminationofthechange
6. Preliminary Treatment for Manganin Samples
of resistance with temperature for precision resistors and
shunts made from sheet materials.
6.1 Inthecaseofmanganinmaterials,afterallthemechani-
cal work has been finished, the specimen shall be given one
3.2 Materialsnormallyusedinthetemperaturerangefrom0
heattreatmentof48hat140 65.0°Candthencooledtoroom
to 80°C may be tested using this test method.
temperature.
6.2 The specimen shall then be given a dip in a nitric acid
This test method is under the jurisdiction of ASTM Committee B02 on
solution (50%) to remove the copper film (which can be
Nonferrous Metals and Alloys and is the direct responsibility of Subcommittee
B02.10 on Thermostat Metals and Electrical Resistance Heating Materials.
judged by the color of the specimen) and then thoroughly
Current edition approved May 1, 2013. Published May 2013. Originally
scrubbed in running water.
approved in 1938. Last previous edition approved in 2007 as B114–07. DOI:
10.1520/B0114-07R13.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or 7. Apparatus
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
7.1 Theapparatusformakingthetestshallconsistofoneor
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. more baths for maintaining the specimen at the desired
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
B114 − 07 (2013)
appreciable errors in the results. With apparatus of good
quality, a change of 1°C in its temperature is allowable.
10.3 The test current shall not be of such a magnitude as to
produceanappreciablechangeinresistanceofthespecimenor
measuring apparatus due to the heating effect. The dimensions
of the specimen should be such that the power dissipated shall
2 2
not exceed 0.02 W/in. (0.003 W/cm ) of exposed surface. To
determine experimentally that the test current is not too large,
the specimen may be immersed in a bath having a temperature
at which it has been found that the sheet has a relatively large
changeinresistancewithtemperature.Thetestcurrentshallbe
appliedandmaintaineduntiltheresistanceofthespecimenhas
become constant. The current shall then be increased by 40%
and maintained at this value until the resistance has again
become constant. If the change in resistance is greater than
0.001%, the test current is too large and shall be reduced until
the foregoing limitation is reached.
10.4 Themeasurementsshallbemadeinsuchawaythatthe
effectsofthermoelectromotiveforcesandparasiticcurrentsare
avoided. When these effects are small, the resistance of the
specimen when measured by a Kelvin bridge may be obtained
byeitheroftwomethods.Inthefirstmethod,thegalvanometer
zero shall be obtained with the galvanometer key open. The
FIG. 1 Test Specimen Showing Terminal Connections
bridge shall be balanced both with the direct and reversed
connection of the battery, the average value of the two results
temperature, thermometers for measuring the temperatures of beingtheresistanceofthespecimen.Inthesecondmethod,the
the baths, and suitable means for measuring the resistance of
zero of the galvanometer shall be obtained with the galvanom-
the specimen. eter key closed and the battery key open. A single balance of
the bridge is then sufficient to obtain the resistance of the
8. Baths
specimen.
8.1 Eachbathshallconsistofchemicallyneutraloil.Theoil
11. Procedure
shall be of such quantity and so well stirred that the tempera-
ture in the region occupied by the specimen and the thermom- 11.1 Connect the test specimen in the measuring circuit and
submerge entirely in the oil bath. For a check on the constancy
etershallbeuniformwithin0.2°Cforanytemperaturebetween
0 and 80°C. of the specimen, make an initial resistance measurement at
room temperature. Raise the temperature of the oil bath or
8.2 In an automatically controlled bath, the temperature of
transfer the specimen to a bath maintained constant at the
the bath at any time during the test at any temperature level
highest temperature at which measurements are to be made.
shall not differ from its mean temperature by more than 0.2°C.
When the test specimen has attained a constant resistance,
In a manually controlled bath, the rate of change of tempera-
recordthereadingofthemeasuringdeviceandthetemperature
ture shall not exceed 0.2°C/min.
of the bath.
9. Temperature Measurement
11.2 Decrease the temperature of the test specimen to the
next lower temperatures either by cooling the bath and main-
9.1 The temperature shall be measured by a calibrated
taining it constant at the next lower temperature, or by
temperature measuring device of suitable precision and accu-
removingthespecimentoanotherbathmaintainedatthelower
racy. The thermometer shall have sufficient sensitivity to
temperature. When the resistance of the specimen has become
indicate temperature changes of 0.1°C. It shall be sufficiently
constant, again make observations of resistance and tempera-
accurate to measure temperature differences to 0.2°C in the
ture.
range from 0 to 80°C.
11.3 In this manner make a series of determinations of the
10. Resistance Measurements
change of resistance with temperature for the desired descend-
10.1 The change of resistance of the specimen shall be ing temperature range.
measuredbyapparatuscapableofdeterminingsuchchangesto
11.4 Take measurements at a sufficient number of tempera-
0.001% of the resistance of the specimen. A Kelvin double
turestodeterminethecharacteristicsofthematerial.Inorderto
bridge, digital ohmmeter, or equivalent is suitable for this
calculate a resistance-temperature equation, tests at three
purpose (see Appendix X1).
temperatures are required. If an independent check is to be
10.2 The temperature of the measuring apparatus shall not made, make observations of at least five temperatures. For
change during the test by an amount sufficient to introduce plotting a curve, six or more observations are generally made.
B114 − 07 (2013)
11.5 Note the temperature of the measuring apparatus at resistance in ohms per ohm in going from 25°C to t , and∆R
1 2
frequent intervals during the test of each specimen. the similar change in going from 25°C to t . That is:
∆R 5 R 2 R /R (7)
~ !
1 1 25 25
12. Resistance-Temperature Equation
and
12.1 Express the results in terms of the constants in an
equation of the following form: ∆R 5 R 2 R /R (8)
~ !
2 2 25 25
R 5 R 11α t 2 25 1β t 2 25 (1)
@ ~ ! ~ ! #
t 25
Then
where:
α 5 ~∆R 2 K ∆R !/K~K11!∆t (9)
2 1
R = resistanceofthespecimeninohmsattemperature, 2
t
β 5 ~K∆R 1∆R !/K~K11!~∆t! (10)
1 2
°C, t,
If K =1, this simplifies to:
R = resistanceofthespecimeninohmsatthestandard
temperature of 25°C,
α 5 ∆R 2∆R /2∆t (11)
~ !
2 1
t = temperature of specimen, °C, and
β 5 ~∆R 1∆R !/1~∆t! (12)
1 2
α and β = temperature-resistance constants of the material.
NOTE 5—A useful alternative method of calculation is presented as
Temperature of maximum or minimum resistance
follows: The resistance-temperature equation is referred to 0°C, and
=25°C−(α⁄2β) relative resistance values are used. For example, over the useful range
from 15 to 35°C, the resistance-temperature curve of manganin is
NOTE 3—This equation will yield either a maximum or a minimum,
parabolic and of the form:
dependingonwhichexistsinthetemperaturerangeinquestion.However,
P 5 P 1At1Bt (13)
t 0
this equation is normally used for those alloys such as manganin, having
atemperature-resistancecurveapproximatingaparabolawithamaximum
where:
near room t
...
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