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Electromagnetic Measurements

Resistance Measurements

DC Resistance Standards

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Technical Contacts:
Randolph E. Elmquist
Tel: 301-975-6591
E-mail: randolph.elmquist@nist.gov

Marlin E. Kraft
Tel: 301-975-4239
E-mail: marlin.kraft@nist.gov

Denise D. Prather
Administration and Logistics
Tel: 301-975-4221
E-mail: denise.prather@nist.gov

Please contact the administration and logistics staff before shipping instruments or standards to the address listed below.

Mailing Address :
National Institute of Standards and Technology
100 Bureau Drive, Stop 8170
Gaithersburg, MD 20899-8170

Calibration fees are the most critical element in funding the metrology services that we provide, and represent the direct cost of providing calibration services for dc resistors and shunts. These services often reach beyond traceability to include detailed consultation. Currently our fees also must recover some of the rapidly increasing costs of providing year-round, readily accessible services and maintaining state-of-the-art traceability through the quantum Hall effect standard. Customers of our most critical calibration services, NIST Service ID numbers 51130C and 51131C, have benefited the most from our efforts to reduce turn-around time through automation, and to provide the world's best level of uncertainty, while keeping these test fees at a reasonable level.

Service ID
Number
Description of Services Fee ($)
51100S Special Resistance Measurement Services, by Prearrangement At Cost
51110M Measurement Assurance Program for Resistance At Cost
51130C Standard Resistor, Thomas-Type, 1Ω 3629
51131C Standard Resistor, Evanohm Wirewound High Precision, 10 kΩ 3407
51132C Standard Resistor, Four-Terminal 0.0001Ω 2385
51133C Standard Resistor, Four-Terminal 0.001Ω 2027
51134C Standard Resistor, Four-Terminal 0.01Ω 2026
51135C Standard Resistor, Four-Terminal 0.1Ω 1499
51136C Standard Resistor, Four-Terminal 1Ω 1499
51137C Standard Resistor, Four-Terminal 10Ω 1499
51138C Standard Resistor, Four-Terminal 100Ω 1499
51139C Standard Resistor, Four-Terminal 1 kΩ 1499
51140C Standard Resistor, 10 kΩ 1986
51141C Standard Resistor, 100 kΩ 2455
51142C Standard Resistor, 1 MΩ 2455
51143C Standard Resistor, 10 MΩ 2994
51144C Additional Voltage, 10 MΩ 2349
51145C Standard Resistor, 100 MΩ 2994
51146C Additional Voltage, 100 MΩ 2349
51147C Standard Resistor, 1 GΩ 2994
51148C Additional Voltage, 1 GΩ 2349
51149C Standard Resistor, 10 GΩ 3911
51150C Additional Voltage, 10 GΩ 3030
51151C Standard Resistor, 100 GΩ 3911
51152C Additional Voltage, 100 GΩ 3030
51153C Standard Resistor, 1 TΩ 4081
51154C Additional Voltage, 1 TΩ 3030
51160C Standard Resistor for Current Measurements (Shunts) with All Determinations at 300 A or Below, One Range, One Current Level 3220
51161C Standard Resistor for Current Measurements (Shunts) with At Least One Determination Above 300 A (maximum current 2000 A), One Range, One Current Level 3560
51162C Standard Resistor for Current Measurements (Shunts), Additional Range of a Multi-Range Resistor 1928
51163C Standard Resistor for Current Measurements (Shunts), Additional Determination at Another Current Level 1928
Fees are subject to change without notice.

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Special DC Resistance Measurements, by Prearrangement (51100S)

Testing or evaluation of prototype resistance standards or measuring instruments; unique resistance measurements; and other calibration services not specified below, such as the determination of the pressure coefficient of Thomas-type or 10 kΩ resistors, the determination of the temperature coefficient of standard resistors, and the calibration of resistance standards in oil at temperatures other than 25 °C, are carried out under this Service ID number. Such measurements are made at the discretion of the NIST technical staff in a manner specifically agreed upon by the customer and the expert involved. Testing of component resistors will only be considered under the rare circumstance that the behavior of the resistors has been observed to approximate that of state-of-the-art standards under the same conditions.

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Measurement Assurance Program for Resistance (51110M)

Resistance MAP transfers are generally carried out at the 1Ω and 10 kΩ levels. Four well-characterized commercial standard resistors are used as transport standards at each level. The suggested measurement schedule at the client laboratory consists of measurements on each transport resistor three times a week for a period of 4 to 6 weeks, depending upon the settling time of the resistors due to transportation effects.

Participation in this program is generally not advisable unless one is required to support resistance measurements with state-of-the-art or near state-of-the-art uncertainties and is willing to adopt a system for the continuous surveillance of standards during the intervals between NIST MAP transfers. A successful transfer requires a considerable amount of data collection and a willingness to become involved in the data analysis process. Data supplied in the course of routine NIST calibrations suffice for normal measurement requirements of standards laboratories if proper methods are used by the laboratory to quantify the additional uncertainties caused by transportation and the laboratory's own measurement process.

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Special Standard Resistors 1Ω and 10 kΩ (51130C and 51131C)

Thomas-type 1Ω resistors or their equivalent are calibrated directly against the NIST 1Ω reference group that is used to maintain the U.S. legal ohm. The values of the reference group are known in terms of the quantum Hall effect. Special 10 kΩ standard resistors designed for air or oil use are calibrated directly against the NIST 10 kΩ working standards. The special 10 kΩ standard resistors (Evanohm wirewound high-precision or equivalent) are characterized by resistance corrections within 10 x 10-6 of nominal value, temperature coefficients of ± 1 x 10-6 /°C at the operating temperature, and drift rates of < 1 x 10-6/year.

The customer's resistors are acclimatized in their respective test environments for approximately 1 week prior to their calibration. Measurement parameters of temperature and current level are shown in Table 9.1 .

Table 9.1 . Temperatures and Current Levels for Customer's Resistors

Resistor Medium Temperature
(°C)
Current
(mA)
oil 25.000 ± 0.003 100
10 kΩ oil 25.00 ± 0.01 1
10 kΩ air 23.0 ± 1.0 1

The temperature of the customer's resistor at the time of the measurement is given in the report of calibration. Since some of these resistors exhibit a significant pressure coefficient, the barometric pressure at the time of the measurement is also reported. Uncertainties are based upon (1) the random behavior of the measurement process as characterized by data from a large population of individual calibrations, and (2) an estimate of the systematic errors arising from such sources as temperature inaccuracies, pressure inaccuracies, scaling errors, etc. Uncertainties are listed in Table 9.2 .

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Table 9.2 . Calibration Uncertainties for Low-power DC Resistance Standards
Note: Resistance uncertainties were changed effective March 8, 2004. See NIST Technical Note 1458.

Service ID
No.
Resistance
(Ω)
Terminal
Connection
Power
(mW)
Relative
Uncertainty U
(x 10-6)
51130C 1 (Thomas) 4 10 0.04
51131C 104 (Special) 5 10 0.08
51132C 10-4 4 10 4
51133C 10-3 4 10 1.2
51134C 10-2 4 10 0.8
51135C 10-1 4 10 0.5
51136C 1 4 10 0.3
51137C 10 4 10 0.3
51138C 102 4 10 0.2
51139C 103 4 10 0.2
51140C 104 4 10 0.2
51141C 105 2 10 0.8
51142C 106 2 10 0.8
51143C-51144C 107 3 * 3 to 8
51145C-51146C 108 3 * 5 to 12
51147C-51148C 109 3 * 10 to 25
51149C-51150C 1010 3 * 20 to 50
51151C-51152C 1011 3 * 50 to 120
51153C-51154C 1012 3 * 100 to 250
51132C-51142C: At the levels of accuracy involved, four-terminal measurements are required for resistors whose nominal values are 10 000Ω or less.
* Resistors at this level are tested at customer-specific voltages up to 500 V for resistors below 1010Ω and 1000 V for resistors at or above 1010Ω. The relative uncertainty depends on the design of the resistor, see NIST Measurement Services for DC Standard Resistors for more information.

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Standard Resistors 10-4Ω to 106Ω (51132C-51142C)

Standard resistors with nominal decade values in the range between 10-4Ω and 106Ω are calibrated by comparison with NIST working standards of equivalent value, known in terms of the Quantum Hall effect. In general, these standards are characterized by (1) resistance corrections within 500 x 10-6 of nominal value, (2) temperature coefficients of < 10 x 10-6 /°C at the temperature of use, and (3) drift rates of < 5 x 10-6/year. Normally, standard resistors are measured in an oil bath maintained at (25.0 ± 0.01) °C, and at a power level of < 0.1 W. Resistors in temperature-controlled enclosures with fixed terminations are also accepted for calibration. At the levels of accuracy involved, four-terminal measurements are required for resistors whose nominal values are 100Ω or less. Expanded uncertainties are based upon (1) the random behavior of the measurement process as characterized by data from a large population of individual calibrations, and (2) an estimate of the systematic errors. Uncertainties are given in Table 9.2 .

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High-Value Standard Resistors: 107Ω to 1012Ω (51143C-51154C)

High-value standard resistors in the range between 107Ω and 1012Ω are calibrated in an air bath maintained at a temperature of (23.0 ± 0.1) °C and at a relative humidity of (35 ± 5)%. The resistors are maintained at these conditions at least 24 hours prior to testing. Customer resistors are compared 1:1 with NIST working standards of the same nominal value up to and including the 1012Ω level. The maximum test voltage is 500 V for resistors < 1010Ω and 1000 V for resistors > 1010Ω. Uncertainties depend upon the stability and performance of the specific resistor involved and are given in Table 9.2 . Only resistors that are mounted in a shielded enclosure with a permanent identifying number and have suitable terminations are accepted for calibration.

The resistance of thin-film, high-valued resistance standards is frequently highly voltage dependent. Hence, the magnitude of the test voltage should be specified by the customer when a resistor is submitted for calibration. The temperature, relative humidity, and test voltage of the resistor are given in the report of calibration.

Special, hermetically sealed high-resistance standards can be calibrated at lower uncertainties than unsealed thin-film resistors. Please refer to NIST Technical Note 1458 for details.

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High-Current Standard Resistors-Shunts (51160C-51163C)

Arrangements should be made with NIST staff prior to submitting a current shunt for calibration at a current level above 400 A. The maximum test current available is 3000 A. The uncertainty of measurement depends largely upon the performance of the customer's resistor involved. Normally only resistors of 0.04% relative uncertainty or less are calibrated. Please refer to NIST Technical Note 1458 for details.

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References-DC Resistance

Characteristics of precision 1 Ω standard resistors influencing transport behaviour and the uncertainty of key comparisons, G. R. Jones, B. J. Pritchard and R. E. Elmquist, Metrologia 46(2009) 503–511 (Jul. 2009).

NIST Measurement Services for DC Standard Resistors, R. E. Elmquist, D. G. Jarrett, G. R. Jones, Jr., M. E. Kraft, S. H. Shields and R. F. Dziuba, Natl. Inst. Stand. Technol. Tech. Note 1458 (Dec. 2003).

Measurement Techniques of Low-Value High-Current Single-Range Shunts from 15 Amps to 3000 Amps, M. Kraft, NCSLI Measure, 2 (1) 44-49, (March 2007).

Temperature and Pressure Coefficients for Thomas 1Ω Resistors, G. R. Jones and R. E. Elmquist, NCSLI Measure, 2 (2) 42-48, (June 2007).

Comparison of Quantum Hall Effect Resistance Standards of the NIST and the BIPM, F. Delahaye, T. J. Witt, R. E. Elmquist, and R. F. Dziuba, Metrologia, 37, 173-176 (2000).

Automated Guarded Bridge for Calibration of Multi-Megohm Standard Resistors from 10 MΩ to 1TΩ, D. G. Jarrett, IEEE Trans. Instrum. Meas., 46 (2), 325-328 (April 1997).

Guidelines for Implementing the New Representation of the Volt and Ohm Effective January 1, 1990, N. B. Belecki, R. F. Dziuba, B. F. Field, and B. N. Taylor, Natl. Inst. Stand. Technol. Tech. Note 1263 (June 1989).

New Realization of the Ohm and Farad Using the NBS Calculable Capacitor, J. Q. Shields, R. F. Dziuba, and H. P. Layer, Conf. Precision Electromagnetic Meas. (CPEM '88), June 7-10,1988, Tsukuba Science City, Japan, Special Issue CPEM '88 IEEE Trans. Instrum. Meas. 38 (2), 249-251 (April 1989).

Determination of the Time-Dependence of Ω NBS Using the Quantized Hall Resistance , M. E. Cage, R. F. Dziuba, C. T. Van Degrift, and D. Yu, Conf. Precision Electromagnetic Meas. (CPEM '88), June 7-10, 1988.

Tsukuba Science City, Japan, Special Issue CPEM '88 IEEE Trans. Instrum. Meas. 38 (2), 263-269 (April 1989).

Monitoring the U.S. Legal Unit of Resistance via the Quantum Hall Effect, M. E. Cage, R. F. Dziuba, B. F. Field, T. E. Kiess, and C. T. Van Degrift, IEEE Trans. Instrum. Meas. IM-36, 222 (June 1987).

The NBS Ohm Past-Present-Future, R. F. Dziuba, Proc. Meas. Science Conf., Irvine, CA (Jan. 1987).

A Test of the Quantum Hall Effect as a Resistance Standard, M. E. Cage, R. F. Dziuba, and B. F. Field, IEEE Trans. Instrum. Meas. IM-34, 301 (1985).

Automated NBS 1-Ohm Measurement System, K. R. Baker and R. F. Dziuba, IEEE Trans. Instrum. Meas. IM-32, 154 (1982).

An Integrated System for the Precision Calibration of Four-Terminal Standard Resistors, T. E. Wells and E. F. Gard, IEEE Trans. Instrum. Meas. IM-20, 253 (Nov. 1971).

Calibration Procedures for Direct Current Apparatus, P. Brooks, Natl. Bur. Stand. (U.S.), Monogr. 39 (Mar. 1962).

Measurement of Multimegohm Resistors, A. H. Scott, J. Res. Natl. Bur. Stand. (U.S.), 50, (3) (Mar. 1953).

Precision Resistors and Their Measurement, J. L. Thomas, Natl. Bur. Stand. (U.S.), Circular 470 (Oct. 1948).

Methods, Apparatus, and Procedures for the Comparison of Precision Standard Resistors, F. Wenner, J. Res. Natl. Bur. Stand. (U.S.), 25, 229, Res. Paper RP1323 (Aug. 1940).

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High-Voltage Standard Resistors

Rate our Services

Technical Contact:
Gerald J. FitzPatrick
Tel: 301-975-8922
E-mail: gerald.fitzpatrick@nist.gov

Denise D. Prather
Administration and Logistics
Tel: 301-975-4221
E-mail: denise.prather@nist.gov

Please contact the administration and logistics staff before shipping instruments or standards to the address listed below.

Mailing Address:
National Institute of Standards and Technology
100 Bureau Drive, Stop 8170
Gaithersburg, MD 20899-8170

Service ID
Number
Description of Services Fee($)
51210C High-Voltage Standard Resistors At Cost
Fees are subject to change without notice.

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High-Voltage Standard Resistors (51210C)

A routine calibration service is maintained for resistors designed for dc high-voltage applications. This service is for corona-free resistors designed for dc operation between 10 kV and 150 kV.

Resistors may be hand-carried or shipped to NIST. If they are shipped, they should be packaged in sturdy reusable containers with convenient access to the resistor. The design of many high-voltage resistors makes them vulnerable to shear-type forces, so provisions should be made to minimize the likelihood of damage due to such forces when the device is in the shipping container.

Users of this service should first discuss scheduling of calibrations with a NIST technical contact. The purchase order should indicate the voltage test points, a mailing address for the calibration report, and a shipping address for the resistor.

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References-High-Voltage Standard Resistors

High-Voltage Divider and Resistor Calibrations, M. Misakian, Natl. Bur. Stand. (U.S.), Tech. Note 1215 (July 1985).

Special Shielded Resistor for High-Voltage Measurements, J. H. Park, J. Res. Natl. Bur. Stand. 66C (1), 1924 (Jan.-Mar. 1962).

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Program questions: Calibrations 
Phone: 301-975-5454, Fax: 301-975-2950
NIST, 100 Bureau Drive, Stop 8363, Gaithersburg, MD 20899-8363