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Dear NIST Impedance Calibration Customers:
The Impedance Calibration Laboratory at NIST-Gaithersburg will be relocating to a different building on the NIST campus at the end of this fiscal year (September-October timeframe). This lab move will require a temporary shutdown of the calibration service. This shutdown will affect calibrations of inductors, capacitors, and capacitance bridges (52100S - 52190S). Other measurement services (52210S - 52711C) listed on this page are not affected by the shutdown.
The transition schedule is as follows:
It is possible that the Impedance Calibration Laboratory could be operational prior to January 2017.
If you would like to be notified when the Impedance Calibration Laboratory is operational, please contact Andrew Koffman and we will inform you of the operational status of the Laboratory.
We apologize for any inconvenience this may cause, and thank you for your patience.
Low-Frequency Capacitance and Inductance Measurements and Standards
Denise D. Prather
Please contact the administration and logistics staff before shipping instruments or standards to the address listed below.
These services cover the calibration of standard capacitors and inductors in the audio-frequency range. Three-terminal standard capacitors having fused-silica (1, 10, and 100) pF, and nitrogen (10, 100, and 1000) pF, dielectrics can be measured at frequencies of (50, 80, 100, 160, 200, 300, 400, 600, 800, 1000, 1600, 2000, 3000, 4000, 6000, 8000, 10000, 12000, 16000, and 20000) Hz. Three-terminal air dielectric standard capacitors from 0.001 pF to 10 000 pF can be measured at (100, 400, and 1000) Hz. Two- or three-terminal capacitors with mica dielectrics in the range from 0.001 µF to 1 µF can be measured at (50, 100, 400, 1000, and 10 000) Hz. Two-terminal air and mica dielectric capacitors with high frequency (HF) coaxial connectors, from 1 pF to 10 000 pF, including GR900 terminations, are calibrated only at 1 kHz. Air-core standard inductors having nominal values between 0.1 mH and 10 H can be measured at (100, 400, and 1000) Hz. Standard inductors of 100 mH or less can also be measured at 10 kHz. Calibration of commercial four-terminal-pair capacitance standards will be considered for measurement under Service ID Number 52100S. This includes values from 1 pF to 10 µF and both capacitance and dissipation factor characterizations are offered. Calibration of impedance standards other than those mentioned above will be considered for Special Test under Service ID Number 52110S (see below). NIST offers calibrations of three-terminal fused-silica and Nitrogen dielectric standard capacitors for dissipation factor at frequencies of (50, 80, 100, 160, 200, 300, 400, 600, 800, 1000, 1600, 2000, 3000, 4000, 6000, 8000, 10000, 12000, 16000, and 20000) Hz under Service ID Number 52110S. Additionally, NIST development of a fused-silica programmable standard capacitor allows Special Tests to be performed for capacitance on accurate three-terminal standards of arbitrary value between 1 fF and approximately 110 pF under Service ID Number 52110S.
This service covers the characterization of capacitance and dissipation factor for standard 4TP air-dielectric capacitors with nominal values of 1 pF, 10 pF, 100 pF and 1000 pF, in the frequency range from 1 kHz to 10 MHz, as well as for standard ceramic capacitors with nominal values of 10 nF, 100 nF, 1 µF, and 10 µF at frequencies of 100 Hz, 1 kHz, 10 kHz, and 100 kHz. For the lower-valued air standards, three-terminal capacitance measurements are taken at 1 kHz for each capacitor under test, thus linking these values to the NIST Calculable Capacitor. Single-port complex impedance measurements are then taken at frequencies in the 100 MHz range, linking these values to the NIST Air Line Standard. Next, a mathematical extrapolation algorithm is used to predict the 4TP resistance and inductance at the test frequencies, and finally the 4TP capacitance and dissipation factor of the capacitor under test are then computed at the test frequencies.
The estimated uncertainties for the 10 pF, 100 pF and 100 pF 4TP capacitance are in the range of 20 ppm to 300 ppm at 1 MHz and in the range of 1100 ppm at 10 MHz. The 1 pF capacitance uncertainties are in the range of 700 ppm for 1 MHz and 14000 ppm (1.4 percent) for 10 MHz. Estimated dissipation factor uncertainties for the 10 pF, 100 pF and 1000 pF standard capacitors lie between 20 microradians (µrad) and 300 µrad at 1 MHz and between 600 and 1400 µrad at 10 MHz. The estimated 1 pF dissipation factor uncertainties are in the range of 300 µrad at 1 MHz and 5700 µrad at 10 MHz. It is recommended that potential customers contact NIST to schedule this measurement service.
The service for air-dielectric standard capacitors of values from 1 pF to 1000 pF will provide capacitance and dissipation factor characterization, with uncertainties for each, at the following frequencies: 1 kHz, 10 kHz, 100 kHz, 500 kHz, 1 MHz, 2 MHz, 3 MHz, 4 MHz, 5 MHz, 6 MHz, 7 MHz, 8 MHz, 9 MHz and 10 MHz. The capacitance characterization is given relative to the 1 kHz value. The frequency curve is highly stable but the actual capacitance values will change significantly with temperature and pressure.
The service for the higher-valued ceramic standard capacitors are performed using two reference standard capacitors (100 pF and 1000 pF) to calibrate low-frequency and high-frequency 10:1 inductive voltage dividers. The IVDs and an LCR meter are used to scale from the known 1000 pF reference up to the 10 nF, 100 nF, 1µF, and 10µF capacitors, providing both capacitance and dissipation factor characterizations with uncertainties at frequencies of 100 Hz, 1 kHz, 10 kHz, and 100 kHz.
This service provides for the testing or evaluation of prototype impedance standards or measurement instrumentation at the state-of-the-art, and other impedance measurements (such as the calibration of decade or variable capacitance standards), at the discretion of NIST technical experts. This service also provides measurement of precision three-terminal standard capacitors with values other than nominal values in the range from 0.001 pF to 110 pF, as well as dissipation factor measurements for precision three-terminal standard capacitors with nominal values of 1 pF, 10 pF, 100 pF, or 1000 pF.
Component capacitors, inductors, and resistors are not considered for testing by NIST unless their performance approximates that of the best available standards. Even under those conditions, calibration will only be done on a limited basis to ascertain the possible use of the components in precision measurement applications.
The cost for such tests are determined on a case-by-case basis, and may be considerably higher than the posted fee for Calibration Services because of needed additional preparation and extra measurements required to perform an uncertainty assessment.
Air-bath type, fused-silica dielectric standard capacitors are generally submitted in temperature-controlled ovens due to their (10 x 10-6)/°C temperature coefficient. Because of the magnitude of the temperature coefficient, it is recommended that a reliable temperature sensor having a resolution of 0.001 °C, or better, be permanently mounted in the oven and thus included as part of the calibration. For baths not so equipped, the temperature is measured in terms of the International Temperature Scale of 1990 (ITS-90), using a standard platinum resistance thermometer.
Some capacitance standards consist of a fused-silica dielectric capacitor completely sealed within a temperature-controlled oven and the ancillary circuitry required for its operation, but with no means of measuring or monitoring the oven's internal temperature. Since the actual temperature of the capacitor cannot be measured, it is not reported. Some such standards measure and display the ambient temperature. For these, the mean value of the display readings taken at the times of measurement is reported, but the significance of this value is decided by the user. Oil-bath type, fused-silica dielectric capacitors are considered for calibration only in a NIST oil bath maintained at (25 ± 0.01) °C. If the capacitors are supplied with built-in sensors, the sensors and the oil temperature are both measured. Requests for the calibration of oil-bath type, fused-silica dielectric capacitors are accepted as Special Tests (52110S).
Calibrations are carried out at (50, 80, 100, 160, 200, 300, 400, 600, 800, 1000, 1600, 2000, 3000, 4000, 6000, 8000, 10000, 12000, 16000, or 20000) Hz, or any combination of these frequencies chosen by the client. A minimum of five measurements is made over approximately a 2-week or longer period, comparing the test capacitor directly with a NIST fused-silica standard. The number of readings taken depends on the stability of the temperature of the test capacitors. The averages of the measured values of capacitance and temperature are reported. The uncertainty of the reported capacitance value depends on the stability of the temperature as well as on the performance of the capacitance standard itself. Because the temperature coefficients of individual standards are usually not known quantitatively, the results cannot be temperature corrected. Despite these factors, the Type A standard uncertainty can be as low as 2 x 10-8 of the capacitor's nominal value. Note that dissipation factor is also available from NIST for fused-silica dielectric standard capacitors under Service ID Number 52110S at the same frequencies offered for capacitance under Service ID Numbers 52130C/52131C above.
The following guidelines apply to the calibration of standard capacitors having dielectrics other than fused-silica.
Calibrations are ordinarily performed at a normal laboratory ambient temperature of (23 ± 1 °C) except for measurements of high-stability nitrogen dielectric capacitors. These are measured more than once in a period of several days to observe their stabilities and to ensure that the variation of the measurements is within the required limit of the standard errors for these measurements. Simultaneously, a digital thermometer is placed near the capacitors to monitor the temperatures during calibrations. The calibration temperature, nominally 23 °C, is reported to within ± 0.01 °C. Relative humidity is maintained at 50% or less in all cases.
Precision three-terminal nitrogen dielectric capacitors, such as ESI Model SC1000 and GENRAD Model 1404, have been found to be variously affected by mechanical shock and orientation. Accordingly, two types of calibrations, featuring different levels of uncertainty are offered. See Table 9.3 . A qualification test (52150C) is available to supplement the small uncertainty calibration (52140C) in order to determine the effects of various impacts (physical shocks) and orientation on the capacitors. Results of this test should be coupled with the Type-B uncertainty of the precision calibration that follows to provide an expanded uncertainty for the calibration of a particular standard. Requests for the small uncertainty calibration without the physical tests are also accepted. For the large uncertainty test (52160C), a similar calibration, but with reduced resolution, is performed. Three-terminal air dielectric capacitors are accepted for the large uncertainty calibration (52160C) only.
In the case of direct or three-terminal capacitance standards, the connectors are assumed to be coaxial, such as the GENRAD Type 874. While the connectors available for this purpose are adequate, it should be noted that changes or instabilities in the impedance of the shield or guard connection of a three-terminal capacitor can change the capacitance significantly.
Capacitors requiring terminal plugs (banana plugs) for parallel connection should be sent to NIST together with the plugs that will be used with the capacitor after calibration. If such a capacitor arrives without plugs, NIST must attach plugs temporarily in order to calibrate the capacitor. Those used by NIST are GENRAD Type 274-P plugs. If, after calibration with these plugs, the capacitor is used with plugs of even slightly different length and base, the capacitance can differ significantly from that reported, and such differences will not be reflected in the calibration uncertainties reported.
Unless otherwise requested, the measured value reported by NIST is the added capacitance when the standard is plugged directly into the binding posts of the NIST bridge. For two-terminal GENRAD capacitors, Type 509 and Type 1409 (when used as a two-terminal capacitor), a capacitance increase ranging from 0.01 pF to 0.04 pF has been found for different plugs. No significant change in conductance has been found in either the two-terminal or three-terminal value. The importance of terminal connection methods becomes extremely critical when capacitance values of 0.01 µF or less are being measured. Improved accuracy in two-terminal measurements can be realized if standards are provided with precision coaxial connectors. The terminal connections, either as two-terminal or three-terminal capacitors, for capacitors with mica dielectric, should be specified in the customer's purchase order. Otherwise, they will be calibrated as two-terminal capacitors (with the case "Ground" connected to the "Low" terminal). The capacitance value given is the equivalent parallel capacitance. In general, an accurate determination of the equivalent parallel conductance with high accuracy is not available. However, for mica dielectric capacitors in an approximate conductance value for each capacitor is also given.
The frequencies available for capacitance calibrations depend upon the type of capacitor and its connectors. In general, capacitors with binding posts or GR 274-P plugs can be calibrated at (50, 80, 100, 160, 200, 300, 400, 600, 800, 1000, 1600, 2000, 3000, 4000, 6000, 8000, 10000, 12000, 16000 and 20000) Hz. Capacitors with high frequency coaxial connectors (GENRAD Type 900) are calibrated only at 1000 Hz.
The expanded uncertainty stated in the Report of Calibration is determined by the random behavior of each type of capacitor (determined from the analysis of measurement data taken from a large population of individual calibrations), as well as an estimate of the systematic errors of the NIST measurement process. These are calculated using the approach of NIST Technical Note 1297, per NIST policy. The expanded uncertainties are given in Table 9.3 and Table 9.4. The stated uncertainties are sufficiently broad to allow for variations in the stray capacitance at the connectors, in temperature of a few degrees Celsius, in relative humidity and atmospheric pressure, and in frequency deviations of a few percent from the stated test conditions. Depending on the frequency and the capacitance value, the relative expanded uncertainty usually lies between 0.0004% and 0.05% (see Tables 9.3 and 9.4 ). The uncertainties do not include allowances for effects of transportation; these must be determined by the owner using pre- and post-calibration data from the owner's facility.
Note that dissipation factor is also available from NIST for Nitrogen dielectric standard capacitors under Service ID Number 52110S at the same frequencies offered for capacitance under Service IDs 52140C/52141C above.
Air-core standard inductors for use in ac bridges are tested at a room temperature of (23 ± 1) °C and a relative humidity of 50% or less. Measurements at 10 000 Hz are limited to standard inductors of 0.1 H or less. Most inductors used at 60 Hz can be tested at 100 Hz since the variation of inductance with frequency in this range is usually negligible. A metal-encased standard is calibrated with the case "Ground" connected to the "Low" terminal of the inductor unless other conditions are specified. The reported values are the self inductance values of the inductors.
References-Low-Frequency Capacitance and Inductance Standards
Evaluation of a Capacitance Scaling System, Svetlana Avramov-Zamurovic, Andrew Koffman, Bryan Waltrip, and Yicheng Wang, IEEE Transactions on Instrumentation and Measurement, Vol. 56, No. 6, December 2007, pp. 2160-2163.
NIST Special Test Service for Four-Terminal-Pair Capacitance Standards from 0.01 F to 100 F, Svetlana Avramov-Zamurovic, Andrew Koffman, and Bryan Waltrip, NIST Technical Note 1486, October 2007.
NIST Measurement Services, Three-Terminal Precision Standard Capacitor Calibrations at NIST, Andrew Koffman, Yicheng Wang, and Scott Shields, NIST Special Publication 250-76, September 2007.
Developing a Dissipation Factor Calibration Service for Standard Capacitors at NIST, Andrew Koffman, Yicheng Wang, and Scott Shields, Proceedings of the 2007 NCSLI Workshop and Symposium, July 29- August 2, 2007, Minneapolis, MN.
Dissipation Factors of 1 pF, 10 pF, and 100 pF Fused-Silica Capacitors, Yicheng Wang, Senior Member, IEEE, Andrew Koffman, Member, IEEE, and Gerald FitzPatrick, Member, IEEE, Proceedings of the IEEE Instrumentation and Measurement Technology Conference (IMTC/2007), May 1-3, 2007, Warsaw, Poland.
Dissipation Factors of Fused-Silica Capacitors in the Audio Frequency Range, Yicheng Wang, Andrew Koffman, and Gerald FitzPatrick, IEEE Transactions on Instrumentation and Measurement, Vol. 56, No. 2, April 2007, pp. 624-627.
Dissipation Factors of Fused-Silica Capacitors in the Audio Frequency Range, Yicheng Wang, Andrew Koffman, and Gerald Fitzpatrick, Proceedings of the 2006 Conference on Precision Electromagnetic Measurements, July 9-14, 2006, Torino, Italy.
Evaluation of Inductive Voltage Dividers and 10 nF Capacitors in a Capacitance Calibration Method, Svetlana Avramov-Zamurovic, Andrew Koffman, and BryanWaltrip, Proceedings of the 2006 Conference on Precision Electromagnetic Measurements, July 9-14, 2006, Torino, Italy.
Optimizing the Use of Commercial Capacitance Bridges in Fused-Silica Standard Capacitor Calibrations at NIST, Andrew Koffman, Yicheng Wang, and Scott Shields, Proceedings of the 2005 NCSLI Workshop and Symposium, July 26-30, 2005, Washington, DC.
Measuring Voltage Balance Using a Switching Scheme, Svetlana Avramov-Zamurovic, Brian Waltrip, Andrew Koffman and George Piper, American Society of Engineering Educators Conference Proceedings, June12-15, 2005, Portland, OR.
Inductance Measurement Using an LCR Meter and a Current Transformer Interface, Svetlana Avramov-Zamurovic, Bryan Waltrip, and Andrew Koffman, Proceedings of the IEEE Instrumentation and Measurement Technology Conference (IMTC/2005), May 17-19, 2005, Ottawa, Ontario, Canada.
Standard Capacitor Calibration Procedure Implemented Using Control Software, Svetlana Avramov-Zamurovic, Brian Waltrip, Andrew Koffman and George Piper, American Society of Engineering Educators Conference Proceedings, June 20-23, 2004, Salt Lake City, UT.
A Balancing Algorithm for Systems with Correlated Injections, Svetlana Avramov-Zamurovic, Bryan Waltrip, Ken Stricklett, and Andrew Koffman, Proceedings of the IEEE Instrumentation and Measurement Technology Conference (IMTC/2004), May 18-20, 2004, Como, Italy.
Improved 1kHz Capacitance Calibration Uncertainty, Anne-Marie Jeffrey and Andrew D. Koffman, IEEE Transactions on Instrumentation and Measurement, Vol. 52, No. 4, August 2003, pp.1284-1288.
The Design and Self-Calibration of Inductive Voltage Dividers for an Automated Impedance Scaling Bridge, B. C. Waltrip, S. Avramov-Zamurovic, and A. D. Koffman, Proceedings of the IEEE Instrumentation and Measurement Technology Conference (IMTC/2002), May 21-23, 2002, Anchorage, AK, USA.
A Capacitance Measurement System Using an IVD Bridge, B. C. Waltrip, A. D. Koffman, and S. Avramov-Zamurovic, Proceedings of the National Conference of Standards Laboratories International (NCSLI) Workshop and Symposium, July 30- August 3, 2001, Washington, DC, August 2001.
Low-Frequency Impedance Calibrations at NIST, A. D. Koffman and Y.M. Chang, Proceedings of the National Conference of Standards Laboratories (NCSL) Workshop and Symposium, July 16-20, 2000, Toronto, Ontario, Canada, July 2000.
The Sensitivity of a Method to Predict a Capacitor's Frequency
Uncertainty Analysis for Four Terminal-Pair Capacitance and Dissipation Factor Characterization from 1kHz to 10 MHz, A.D. Koffman, S.Avramov-Zamurovic, B.C. Waltrip, and N.M. Oldham, IEEE Transactions on Instrumentation and Measurement, Volume 49, No. 2, pp. 346-348, April 2000.
Error Analysis and Calibration Uncertainty of Capacitance Standards at NIST, Y. May Chang, NIST Spec. Publ. 250-52 (Jan. 2000).
Capacitance and Dissipation Factor Measurements from 1 kHz to 10 MHz, A. D. Koffman, B. C.Waltrip, N. M. Oldham, and S. Avramov-Zamurovic, Proceedings of the National Conference of Standards Laboratories (NCSL) Workshop and Symposium, July 19-23, 1998, Albuquerque, NM, pp. 63-68.
Uncertainty Analysis for Four Terminal-Pair Capacitance and Dissipation Factor Characterization from 1 kHz to 10 MHz, A. D. Koffman, S Avramov-Zamurovic, B. C. Waltrip, and N. M. Oldham, Proceedings of the IEEE Instrumentation and Measurement Technology Conference (IMTC/99),May 24-26, 1999, Venice, Italy, pp. 346-348.
The Sensitivity of a Method to Predict the Frequency Characteristic of a Capacitor, S. Avramov-Zamurovic, A. D. Koffman, N. M. Oldham, andB. C. Waltrip, Proceedings of the IEEE Instrumentation and Measurement Technology Conference (IMTC/99), May 24-26, 1999, Venice, Italy, pp. 398-404.
NIST Calibration Service for Capacitance Standards at Low Frequency, Y. May Chang and S. B. Tillett, NIST Spec. Publ. 250-47 (Apr. 1998).
NIST Measurement Assurance Program for Capacitance Standards at 1 kHz, Y. May Chang, NIST Technical Note 1417 (March 1996).
NIST Capacitance Measurement Assurance Program (MAP), Y. May Chang, Measurement Science Conference, Anaheim, CA, (January 1993).
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).
Testing to Quantify the Effects of Handling of Gas Dielectric Standard Capacitors, C. R. Levy, Natl. Bur. Stand. (U.S.), Tech. Note 1161 (1982).
New NBS Measurements of the Absolute Farad and Ohm, R. D. Cutkosky, IEEE Trans. Instrum. Meas., IM-23 (4), 305 (Dec. 1974).
Applications of Coaxial Chokes to AC Bridge Circuits, D. N. Homan, J. Res. Natl. Bur. Stand. (U.S.), 72C (2) (June 1968).
Improved Ten-Picofarad Fused Silica Dielectric Capacitor, R. D. Cutkosky and H. L. Lee, J. Res. Natl. Bur. Stand. (U.S.), 69C (3), 173 (Sept. 1965).
Calibration of Inductance Standards in the Maxwell-Wein Bridge Circuit, T. L. Zapf, J. Res. Natl. Bur. Stand. (U.S.), 65C (3) (Sept. 1961).
Capacitance Bridge NBS Type 2, R. D. Cutkosky, Natl. Bur. Stand. (U.S.), Report 7103 (Mar. 1961).
Puanani L. DeLara
Please contact the administration and logistics staff before shipping instruments or standards to the address listed below.
Fees are subject to change without notice.
Services provided in this category (and also Service ID Numbers 51310S and 52710C) are for passive devices over the frequency range from 10 kHz to 250 MHz. Highest accuracy is obtained only for standards equipped with precision coaxial connectors. Standards submitted for calibration should be in good repair and, except for very minor cleaning of connector surfaces, should require no pre-calibration maintenance. NIST does not provide repair services; items received that require maintenance will be returned to the sender and a handling fee charged.>
Calibration services for some types of capacitance standards at frequencies as low as 1 kHz can be provided by the NIST Boulder Laboratory if the accuracy requirement does not exceed 0.01%. In some circumstances this can eliminate the necessity of sending a standard to both the Gaithersburg and Boulder Laboratories for a complete calibration. For additional details, please consult with the technical contact listed at the beginning of this section.
Calibration services are not provided for measuring instruments such as bridges or meters. The uncertainty of these instruments should be verified by the owner through the use of stable standards especially selected for particular values and frequencies appropriate to the instrument in question.
All calibrations are performed under typical ambient laboratory conditions of 23 °C, and an atmospheric pressure of approximately ((8.4 ± 0.2) x 104) Pa at Boulder, Colorado. Services at ambient conditions outside these limits are not provided. Also, the power applied to any device being calibrated does not exceed 1 W. Additional information about immittance (impedance and admittance) measurement and standards are contained in the references.
In the frequency range from 10 kHz to 250 MHz, capacitance calibrations are available from 1 pF to 1000 pF depending upon frequency. The upper capacitance limit for calibration decreases as the frequency increases and is 50 pF above 30 MHz.
From 100 kHz to 30 MHz, a special high-accuracy service is available for capacitors with nominal values of (50, 100, 200, 500, and 1000) pF if equipped with 14 mm coaxial connectors. The minimum relative expanded uncertainty* is 0.01% for the high accuracy device and 0.1% for the other calibrations.
Reports of Calibration for capacitors normally do not give conductance values because the conductance values of capacitors of standard quality, especially those with air-dielectric, are too small to be measured accurately at the present state of the art.
A technique for extrapolating the 1 kHz values of capacitance standards to high frequencies is described by R. N. Jones (see 1963 reference). That reference describes a technique for obtaining a high-frequency value of a capacitor equipped with an unshielded (banana plug) connector. The measurement technique yields effective capacitance values at high frequencies using the capacitance value at 1 kHz and the residual series inductance. The same technique, with some modifications, is usable for three-terminal and four-terminal pair capacitors. It is emphasized that these extrapolation procedures are only usable for air dielectric capacitors or capacitors with insulating materials whose dielectric constant does not change with frequency.
Fixed-value reference standards are maintained by NIST for values of 10 pF, 100 pF, and 1000 pF. High-quality three-terminal air dielectric capacitance standards should have low residual series inductance (< 0.1 µH). This being the case, it may be assumed that, to within an expanded uncertainty of 0.10%, the capacitances of standards of 1 pF or less with air-dielectric is the same at 1 MHz as it is at 1 kHz. Thus, it is unnecessary to have capacitors smaller than 10 pF calibrated at 1 MHz.
In the frequency range from 10 kHz to 250 MHz, inductance calibrations to a minimum expanded uncertainty of 0.1% are available from 0.01 µH to 1 mH. The upper inductance limit for calibration decreases as the frequency increases and is 1 µH at 250 MHz. In the Report of Calibration, the resistance of the inductor is also given. Service is available only for air-core inductors or inductors whose value is independent of current.
References-High-Frequency Standard Capacitors and Inductors
Calibration Service for Low-Loss, Three-Terminal Capacitance Standards at 100 kHz and 1 MHz, G. M. Free and R. N. Jones, Natl. Inst. Stand. Technol. (U.S.), Tech. Note 1348 (Feb. 1992).
Evaluation of Three-Terminal and Four-Terminal Pair Capacitors at High Frequencies, R. N. Jones, Natl. Bur. Stand. (U.S.), Tech. Note 1024 (Sept. 1980).
The Measurements of Lumped Parameter Impedance: A Metrology Guide, R. N. Jones, Natl. Bur. Stand. (U.S.), Monogr. 141 (June 1974).
A Precision High-Frequency Calibration Facility for Coaxial Capacitance Standards, R. N. Jones and L. E. Huntley, Natl. Bur. Stand. (U.S.), Tech. Note 386 (Mar. 1970).
Lumped Parameter Impedance Measurements, L. E. Huntley and R. N. Jones, Proc. IEEE 55(6), 900 (June 1967).
A Technique for Extrapolating the 1 kc Values of Secondary Capacitance Standards to Higher Frequencies, R. N. Jones, Natl. Bur. Stand. (U.S.), Tech. Note 201 (Nov. 1963).
A Calibration Service for Voltage Transformers and High-Voltage Capacitors, W. E. Anderson, Natl. Bur. Stand. (U.S.), Spec. Publ. 250-33 (June 1988).
An International Comparison of High-Voltage Capacitor Calibrations, W. E. Anderson, R. S. Davis, O. Petersons, and W. J. M. Moore, IEEE Trans. Power Appar. Syst. 97 (4), 1217 (July 1978).
A Wide Range High-Voltage Capacitance Bridge with One PPM Accuracy, O. Petersons and W. E. Anderson, IEEE Trans. Instrum. Meas. IM-24 (4), 336 (Dec. 1975).
Puanani L. DeLara
Please contact the administration and logistics staff before shipping instruments or standards to the address listed below.
Standards for Q-measurements are maintained at NIST. These are high-Q inductors equipped with banana plug connectors at a spacing of 1 inch on centers. These standards have inductance values of (0.25, 2.5, 25, 250, 2500, and 25 000) mH, and effective Q-values from 100 to approximately 600. These serve as working standards for calibration of Q-standards of a similar type. Calibration frequencies range from 50 kHz to 45 MHz. The calibration report includes effective resonating capacitance and effective Q. Relative expanded uncertainties are of the order of 0.2% for capacitance and 2% for Q. Provisions are made for calibrating each Q-standard at three frequencies; however, adequate assurance of stability is usually provided by re-calibrating only at the center frequency.
Standards for the Calibration of Q-Meters, 50 kHz to 45 MHz, R. N. Jones, J. Res. Natl. Bur. Stand.(U.S.), 68C (4), 243 (Oct.-Dec. 1964).