Centre for Electricity

14.07.2011 10:17

ELECTRICAL RESISTANCE AND CAPACITANCE
LOW-FREQUENCY QUANTITIES
HIGH-FREQUENCY QUANTITIES
QUANTUM STANDARDS AND DIRECT QUANTITIES

Contact:

Eng. Štefan Gašparík
Director of the Centre
tel.: 02/60294 360
e-mail: gasparik@smu.gov.sk

Eng. Eva Gombárová
tel.: 02/ 602 94 360
fax.: 02/ 654 29 592
e-mail: gombarova@smu.gov.sk

ELECTRICAL RESISTANCE AND CAPACITANCE LABORATORY

1. ELECTRICAL RESISTANCE

Quantity - Electrical Resistance.

Unit - Ohm (Ω).

Tasks of the laboratory
The main task of the laboratory is the realisation and maintenance of the electrical resistance standards and their scale in National Standard of Electrical Resistance.

International comparisons
DUNAMET Project D 9.
International comparison by the PHARE programme PRAQ III of the European Committee for Standardisation (CEN).

Available metrological services
Verification of resistance reference standards og 1.order using a DC (in a range form 10^-4 to 10⁹ Ω) and 2., 3. orders (in a range from 10⁹ to 10¹² Ω). Verification of resistance bridges and resistor decades using a DC, resistance voltage dividers, resistance shunts, resistance ranges of multimeters and calibrators (in a range from 10^-4 to 10¹² Ω). Determination of the temperature coefficient of a standard, in a limited range of thier loading characteristics and exams of precise operation meters.Verification of reference standards of 2. and 3. orders and AC resistor decades at AC (in the range from 1 Ω to 10⁵ Ω at a frequencies from 80 to 1600 Hz) with an option to determine their frequency dependance.

Methods of measurement:

a method of direct comparison with working standards of the SMU or method of substitution are used in the verification of reference standards of 1. and 2. orders.
AC resistors in a range of 1 - 10⁵Ω are compared using a direct substitution method with a reference standard. It is possible to find out the frequency characteristics for the range of frequencies of 80 - 1600 Hz and time constant of the standard. The relative combined standard uncertainties for these resistances are from 1x10^-6 to 1x10^-5.

Instruments in use

National Resistance Standard (a group of standards consisting of 1 Ω sealed standards and a gropu of precise 10 kΩ standards). An accuracy of resistance measurements at the SMU is verified by a regular comparison of transfer standards 1Ω and 10 kΩ to value in BIPM (other comparisons at 1986, 1991, 1996).
Working standards - decimal value in the range of 10-⁴ to 10¹⁰ Ω and combined transfer standards in the range of 1 to 10¹² Ω.
DC current comparator bridge produced by Guidline Co. (model 9920) for calibration of small values standards (up to 1 kΩ) and calibration of current shunts pu to 100 A with relative combined standard uncertainty of direct measurements from 1x10^-5 to 1x10^-7. Wheastone bridge produced by Tinsley Co. (model 5577 A) and a high-value bridge developed in SMU which relative uncertainties at direct measurements from 3x10^-3 to 2x10^-6 in accordance with used range. Double AC resistance bridge developed in SMU with indictuvely coupled ratio arms, with combined standard uncertainties of resistance measurements from 3x10^-4 % to 5x10^-5 %.

Primary standards of resistance with a calculate frequency dependence up to 1600 Hz and AC working resistance standards of Tinsley type 5684 with nominal values of 1Ω - 10 kΩ.
The laboratories of resistance operated at the basic temperature of 23°C stabilised within ± (0.2 - 0.5)°C. The temperature, humidity and atmospheric pressure are recorder for correction requirements.

Contact
Eng. Ľubomír Harich, Eng. Štefan Gašparík
phone: + 421 2 60294 363 phone: + 421 2 60294 235
e-mail: harich@smu.gov.sk e-mail: gasparik@smu.gov.sk

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2. ELECTRICAL CAPACITANCE

Quantity - Electrical Capacitance.

Unit -- Farad (F).

Tasks of the laboratory
The main task of the Laboratory is the realisation and maintenance of the capacitance standards and their scale in National Standard of Capacitance.

International comparisons
The National Standard of Electrical capacity performs the realisation and the reproduction of the unit of capacitors with a nominal value of 10 pF at the frequency of 1 kHz with a standard deviation of 1x10-7 of rdg with limits of combined standard uncetrainty of 1.7x10-6 of rdg and relative uncertainty arised from the time unstability more than 3x10-7 of rdg per year. The primary standard was compared to the standards of electrical capacity at PTB Braunschweig (1997).
COOMET - Project 131/DE/95.

Available metrological services
Verification of reference standards of electrical capacity of accuracy classes 1, 2, 3 at frequency of 1 kHz within the measuring range from 1 pF to 10 µF. Verification of capacity decades of accuracy classes 2, 3 and capacity bridges at frequency of 1 kHz and measuring range up to 100 µF.

Methods of measurement:

a comparative method. This method is used for verification of capacitance standards: the bridge measuring methods (comparison of tested capacitor to a comparing standard capacitor; the selection of method is given by a required accuracy measuring of electrical capacitance), the substitution method (comparison of verified capacitor to the reference standard of the same nominal value in the same arm of bridge), method of direct comparison (comparison of verified capacitor to the working standard of the other nominal value using a division of 1:1 to 1:10 in different arms of bridge), method of direct measurement (measurement of capacitor with a direct value reading).

Instruments in use

Working standards of electrical capacity of reported values from 1 pF to 10 µF, hermetic capacitor with quartz or mica dielectric with a dissipation factor of less than 1x10^-5 and temperature coefficient from 2x10^-6 to 2x10^-5 with stability of its values more than 2x10-5 and with the overall uncertainty of values from 5x10^-6 to 5x10^-4. General Purpose Radio transformer bridge of GR 1620-A type with the measuring ranges capacity from 10 aF to 1.11110 µF (or 11.11110 µF), conductance from 10^-6 µS to 100 mS, dissipation factor from 1x10^-6 to 1, with a measuring voltage up to 100 V and measuring frequency from 50 Hz to 10 kHz. The uncertainty of reading of capacity values by the direct measurement is 1x10^-4 and by the comparison substitute method is 1x10

Contact
Eng. Štefan Gašparík
phone: + 421 2 60294 235
e-mail: gasparik@smu.gov.sk

LOW-FREQUENCY QUANTITIES LABORATORY

1. POWER AND ENERGY OF AC CURRENT AT LOW FREQUENCY

Quantity - AC Power is derived phsycal quantity, which is defined as a conjuction of voltage, current and power factor. AC Energy is derived physical quantity, which is defined as a conjunction of AC Power and time.

Unit - Watt (W) is the unit of AC Power. Other units are mW, kW, MW.
Ws is the unit of AC Energy. Other units are kWh, MWh.

Tasks of the laboratory
The main tasks of laboratory are research, development and realisation of the units of AC Power and AC Energy and their transfer to working standards.

International comparisons
1998 - Comparison measurement within the project COPERNICUS between SMU, PTB, OMH.
2000-2001 - Comparison measurement within bilateral co-operation between CMI and SMU.

Available metrological services
Calibration of secondary standard wattmeters and wattmeters calibrators. Calibration of static standard electricity meters equipment for electrical energy meters. Pattern testing for electrical energy meters of the accuracy class 0.2, 0.5, 1 and 2 (IEC 60521, IEC 61036, IEC 60687). Pattern testing equipment for electrical energy meters (IEC 60736).

Methods of measurement:

indirect method of power measurement (calibration of secondary standard wattmeters and wattmeters calibrators);
direct method of power measurement or indirect method of power measurement with sequential measure of voltage current and power factor (calibration of secondary standard wattmeters);
indirect method of constant power and the time measurement (calibration of secondary standard electricity meters);
indirect method of measure power and of the time or method energy comparison (calibration of equipment for electrical energy meters of the accuracy class 0.2S, 0.5S, 1 and 2.

Expanded uncertainty (for k=2) of an assignment of a relative error of secondary standard:

wattmeters within the voltage range from 50 V to 220 V, the current range from 0.5 A to 5 A and power factor from 1 to 0.5 lag or lead at the frequency 50 Hz is in the span 0.016 % - 0.024 %;
energy measurements, equipment for electrical meters of the accuracy class 0.2S, 0.5S, 1 and 2 within the voltage range from 50 V to 220 V, the current range from 0.5 A to 5 A and power factor from 1 to 0.5 lag or lead at the frequency 50 Hz is in the span 0.016 % - 0.024 %.

Supplementary activities of laboratory
Experts' report about laboratory of aplicants to accordance with authority to attest electricity meters according to the Act of Metrology in Slovakia. Expertises of pattern testing electicity meters which were confirm abroad or were primary attested abroad. Pattern testing electricity meters to confirm type. Development of developing projects and guides of quality to calibration secondary standards of the electrical power and energy. practice cources with practical training needed for workers who are performing attest electricity meters. Working out of educational text and specific grant publications from area of attest electricity meters.

Instruments in use
The reference Standard of the Power and Energy of AC Current consists: syntethic constant AC voltage supply with voltage regulation of output voltage from 50 V to 220 V; syntethic constant AC current supply with current regulation of output current from 0.5 A to 5 A and with phase shift to the output voltage of AC voltage supply about ± 90°; syntethic constant AC auxillary voltage supply with output voltage 0.5 V to 1 V and with phase shift to the output voltage of AC voltage supply about ± 90°; DC calibrator Datron - Wavetek 4808 at the voltage range 100 V or 1000 V; AC/DC Thermal Transfer Standard Fluke 540B for the voltage range from 0.5 V to 1000 V; a set of AC standard resistors with nominal value 0.1 and 1 ; inductive voltage divider with fixed divided rations 220/1 V and 100/1 V; counter of impulses RTF 2005.500.
Working standards used as components of reference standard. The calibration of the standard measures of the RMS voltage and current is performed in the air-conditioned laboratories with temperature 23°C ± 1°C and of span relative humidity 25 % - 75 %. The traceability of individual parts of the standard is realised by traceable to the Slovak National Standards of DC voltage scale, time and resistance.

Contact
Eng. Ján Hanák
phone: + 421 2 60294 358
e-mail: hanak@smu.gov.sk

Eng. Dragos Alexandrescu
tel.: 02/ 602 94 282
e-mail: alexandrescu@smu.gov.sk

Eng. Peter Samuhel
phone: + 421 2 60294 304

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2. ROOT MEAN SQUARE (RMS) OF AC VOLTAGE AND CURRENT

Quantity - RMS of AC voltage, RMS of AC current.

Unit - Volt (V) is the unit of RMS of AC voltage. Other units are mV, kV. Ampere (A) is the unit of RMS of AC current. Other units are mA, kA.

Tasks of the laboratory
The main task of the laboratory are research, development and realisation of the units of RMS of AC voltage and current and their transfer to working standards.

International comparisons
1999 - Comparison measurement within the EA Interlabolatory Comparison EI 27.

Available metrological services
Calibration of standard measures of the RMS voltage up to 1000 V and in the frequency span 40 Hz - 40 kHz, of the RMS current up to 5 A at the frequency 50 Hz. Calibration of AC digital voltmeters and ammeters with resolution 7 1 and 8 1 digits. calibration of calibrators of a root mean square of AC voltage and current with display resolution 6 1 and 7 1 digits.

Methods of measurement:

the method of direct measurement (comparison) is used to the calibration of the standard measures (calibrators) of the RMS voltage and to the calibration of the digital voltmeters and ammeters;
the method of indirect measurement as voltage drop at the AC standard resistor is used to the calibration of the standard measures (calibrators) of the RMS current;

Expanded uncertainty (for k=2) of an assignment of a relative error of secondary standard measures of the:

RMS voltage within the range from 0.5 V to 500 V is 0.012 % of RDG and within the range from 500 V to 1000 V is 0.024 % of RDG in the frequency span 40 Hz - 40 kHz;
RMS current within the range from 2 mA to 10 A is 0.012 % of RDG at the frequency 50 Hz.

Instruments in use

The reference standard of the RMS Voltage and Current consists of AC/DC voltage and current calibrator (DATRON-WAVETEK 4808, for the voltage range from 10 mV to 1000 V, for the current range from 10 µA to 1 A in the frequency span 40 Hz - 40 kHz), transconductance amplifier (DATRON-WAVETEK 4600 for the current range up to 10 A), AC/DC Thermal Transfer Standard (Fluke 540B for the voltage range from 0.5 V to 1000 V), set of AC standard resistors (nominal value 0.1 Ω and 1 Ω) digital voltmeter (Solartron 7081 for the voltage range up to 1000 V) and instruments for measurement of air temperature, barometric pressure and relative humidity.
The calibration of the standard measures of the RMS voltage and current is performed in the air-conditioned laboratories with temperature 23.0°C ± 1°C and of span relative humidity 25 % - 75 %. The traceability of individual parts of the standard is realised by traceable to the Slovak National Standards of DC voltage scale and resistance.

Contact
Eng. Ján Hanák
phone: + 421 2 60294 358
e-mail: hanak@smu.gov.sk

Eng. Dragos Alexandrescu
tel.: 02/ 602 94 282
e-mail: alexandrescu@smu.gov.sk

Eng. Dušan Rudohradský
phone: + 421 2 60294 239

Eng. Peter Samuhel
phone: + 421 2 60294 304

HIGH-FREQUENCY QUANTITIES LABORATORY

1. RF VOLTAGE

Quantity - RF Voltage.

Unit - Volt (V).

Tasks of the laboratory
The main task of laboratory is the realisation of RF Voltage standard unit and its traceability to working standards.

International comparisons
GT-RF 92-6 (CCEEM.RF-K4.CL), HF 2.

Available metrological services
Calibration of secondary standards of I. and II. orders within the range from 1 µV to 1 V and the frequency range from 50 kHz to 1 GHz respectively from 2 V to 30 V and frequency range from 50 kHz to 30 MHz. Ranges and uncertainties are dependent on frequency and amplitude.
Calibration of the HF voltage measuring instruments for industrial use and for the telecommunications.

Methods of measurement:

the HF primary voltage standard in the frequency range from 50 kHz to 1000 MHz was developed at the SMU. The unit is derived from thermal effects of RF power and the physical model of scanning element (thermistor). Elements of model are determined by length variation of thermistor leads and nominal value of resistance of thermistor. The real value of RF voltage in a given level of RF wiring is determined by calculation on the base of stated elements of thermistor equivalent scheme. It is calculating standard based on linear measures and DC quantities;
other method of determination of RF voltage values is based on primary standards of RF power and RF impendance. The obtained value are verified in international comparison measurements with NMI's;
the scale of RF voltage unit, which is transfered by secondary standards at meters in accordance with customer's demands is derived by a suitable method providing the linearity of transfer;
the thermistor and thermocouple mounts measurements, e.g. firms Fluke, Hewlett-Packard, high frequency wide-band and selective voltmeters, spectral analysers and oscilloscopes, measurement of ascending level of signal generators in the range of 10 kHz up to 1 GHz are carried out for purposes of industry, telecommunications and defence. The uncertainty range is in accordance with a frequency range and nominal value of measured power from 0.05 % to 10 %.

Instruments in use
The working standards within a voltage range from 100 mV to 1 V and a frequency range from 50 kHz to 1 GHz. The standard mounts for voltage ranges up to 30 V and frequency ranges to 30 MHz.

Contact

Eng. Peter Vrabček, Phd
phone: + 421 2 60294 385
e-mail: vrabcek@smu.gov.sk

Eng. Marek Ralbovský
phone: + 421 2 60294 369
e-mail: ralbovsky@smu.gov.sk

Mrs. Katarína Mokrošová
phone: + 421 2 60294 234

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2. RF AND MICROWAVE POWER

Quantity - RF and Microwave power.

Unit - mW, W.

Tasks of the laboratory
The main task of the laboratory is the realisation of RF and microwave power primary standard unit and its traceability to working standards.

International comparisons
EUROMET No. 393.

Available metrological services
Calibration of secondary standards of I. and II. orders from 10 µW to 1000 mW in the frequency range from 10 MHz to 18 GHz (coaxial line of 50 , 7/3 mm), ranges and uncertainties are dependent on frequency and power. Calibration of secondary standards of I. and II. orders from 1 mW to 10 mW in the frequency range from 8.2 GHz to 12.4 GHz (waveguide). Calibration of RF power measuring instruments for purposes of industry and telecommunications.

Methods of measurement:

primary standards of RF power in a frequency range from 10 MHz to 18 GHz were devepoped at the SMU. Nominal value of measured RF power is 10 mW at a primary level. The power unit is derived from comparison of RF thermal effects to the equivalent effects of given DC quantity, which value is possible to be determined with a very low uncertainty. The scale of RF power unit, which is transfered by secondary standards at meters in according with customer's requirements, is derived by a suitable method providing a linearity of transfer. Thermistor, baretter and thermocouple mounts to the power meter of different producers in the range from 10 MHz to 18 GHz in accordance with customer's demands from 10 MHz to 18 GHz in the coaxial line resp. from 8.2 GHz to 12.4 GHz in waveguide.

The range of calibrated power is from 100 µW up to 1000 mW (up to 1 GHz only) at higher frequencies to 70 mW. The combinated standard uncertainty of measurement of standard mounts according to frequency range and nominal value of RF power range is from 0.3 % to 1.2 %.

Instruments in use
Working standards in a range from 1 mW to 10 mW in a frequency range from 10 MHz to 18 GHz in the coaxial line of 7/3 mm. Standard power measuring mounts for an X-band waveguide.

Contact

Eng. Peter Vrabček, Phd
phone: + 421 2 60294 385
e-mail: vrabcek@smu.gov.sk

Eng. Marek Ralbovský
phone: + 421 2 60294 369
e-mail: ralbovsky@smu.gov.sk

Mrs. Katarína Mokrošová
phone: + 421 2 60294 234

1. DC CURRENT

Quantity - DC Current.

Unit - Ampere (A), miliampere (mA), microampere (µA).

Tasks of the laboratory
The main task of the Laboratory is the maintainance amd improvement through the development of the reference standard of DC Current in the range (0 - 20) A. The current in this range is disseminated to the working standards. The Laboratory performes the calibrations for customers.

International comparisons
The Laboratory has not participated in the international comparison. The standard is calibrated at DC Voltage and DC Resistance standards.

Available metrological services
Calibration of standard current sources and calibrators up to 20 A:
Calibration of digital ampermeters up to 10 A:
Consulting services and expertises.

Methods of measurement:

for calibration of the secondary standards and ordinary instruments the following methods are used: digital ammeters (indirect method of measurement by means of external source); standard sources, calibrators (method of indirect measurement). The calibration is performed at the laboratory temperature of (23.0 ± 1.0)°C.

Instruments in use
The working standard of DC current is a device on the following main components: standard calibrator DATRON 4808, standard digital voltmeters SOLATRON 7081, a set of standard resistors R331, R321 and Norma.
Traceability to a higher standard order: standard calibrator DATRON 4808 and standard digital voltmeter SOLATRON 7081 are regulary calibrated by the National Primary Voltage Standard; a set of standard resistors is regulary calibrated by the National Resistance Standard.

Contact

Eng. Dušan Rudohradský
phone: + 421 2 60294 239

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2. SCALE OF DC VOLTAGE FROM 10 TO 1000 V

Quantity - DC Voltage.

Unit - Volt (V), milivolt (mV), microvolt (µV), nanovolt (nV).

Tasks of the laboratory
The main task of the laboratory is the maintainance and improvement through the development of the primary national standard of DC Voltage Scale in the range (10-1000) V. The voltage in this range is disseminated to the reference standards. The laboratory performes the international comparisons of the primary standard and calibrations for customers.

International comparisons
The laboratory has participated in international comparison in the framework of EUROMET, project No. 449.

Available metrological services
Calibration of standards voltage sources and calibration up to 1000 V.
Calibration and adjustmant of digital voltmeters up to 1000 V.

Consulting and expertises.

Methods of measurement:

for calibration of secondary standards and ordinary instruments following methods are used: calibrators (direct comparison with the voltage scale standard), digital voltmeters (direct measurement of the standard sources). The calibration is performed at the laboratory temperature of (23.0 ± 1.0)°C.

Instruments in use
The National Standard of DC voltage scale in a range 10 V - 1000 V consists of the following components: electronic DC voltage reference standard DATRON 4910 (nominal value 10 V); standard voltage divider - type Guildline 9700PL .

Contact
Eng. Dušan Rudohradský
phone: + 421 2 60294 239

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3. DC VOLTAGE UNIT AND SCALE FROM 0 TO 10 V

Quantity - DC Voltage.

Unit - Volt (V), milivolt (mV), microvolt (µV), nanovolt (nV).

Tasks of the laboratory
The main task of the laboratory is the maintainance and improvement through the development of the primary national standard of DC Voltage based on the Josephson effect. The voltage unit is disseminated to the reference standards of the SMU for the standard of the DC Voltage Scale. The laboratory performes the international comparisons of the primary standard and calibrations for customers.

International comparisons
The results of international comparisons are in the following references:

Vrabček, P.: Two international comparison of SMU 10 V Josephson Array Voltage Standard. CPEM'98. Conference Digest, Washington, USA, 1998.
Vrabček, P.: Quantum standards of voltage and resistance as the base of electricity metrology in Slovakia. proceedings of 9th International Metrology Congress, Bordeaux, France, 1999.
Reymann, D. - Witt, T.J. - Vrabček, P. et all: Recent developments in BIPM voltage standard comparisons. In: 2000 Conference on Precision Electromagnetic Measurements Digest, 14-19, May 2000, Sydney, Australia, p.253-254.
International comparison. Final Report. DC reference standard with 1.018 and 10 V. Organising bodies EUROMET and CEN-TCU. Co-ordinator: Luc Erard, BNM-LCIE. Pilot Laboratory NMi Van Swinder laboratory. July 2000.
Avrons, D. - Reymann, D. - Vrabček, P. - Witt, T.J.: Bilateral Comparison of 10 V and 1.018 V Standards between the SMU and the BIPM, May - October, 1998. rapport BIPM-9/01.
Reymann, D. - Witt, T.J. - SENIOR MEMBER - IEEE - Vrabček, P. - Tang, Yi. - Hamilton, C.A. - Fellow, IEEE - Katkov, A.S. - Jeanneret, B. - Power, O.: Recent Developments in BIPM Voltage Standard Comparisons . In: IEEE Transactions on Instrumentation and Measurement, vol.50, 2001, No.2, p.206-209.
Vrabček, P. - Reymann, D. - Witt, T.J.: Bilateral Comparison of 1.018 V and 10 V Standards between the SMU, Slovakia and the BIPM, April 2001. Rapport BIPM-2001/05. BIPM: 2001, p.1-7.

Available metrological services
Calibration of the standard Weston cells and electronic standards of DC voltage of 1 V - 10 V at the laboratory of SMU or customer's laboratories. It includes the transportation of the SMU's reference standard to customer's laboratories where the verification will be performed. The reference standard, after returning back to SMU, will be re-calibrated. It is possible to reduce, to some extend, errors caused by changes of voltage of reference standard during the transportation. And calibration of the precise DC digital voltmeters (at least 8 digits) in a range from 0 to 10 V.

Methods of measurement:

a basic measuring method is a differencial method. The main source of errors is a noise voltage of the calibrated electronic supplies of voltage as well as unstability of thermoelectric voltage. The result uncertainty for one measurement cycle by 10 V is typically 100 nV. The standard type B uncertainty of the primary standard based on the Josephson effect is 20 nV.

Instruments in use

The primary standard is based on inversion Josephson's effect consisting of junction array for a nominal output value of DC voltage 10 V, located in a cryostat at the temperature of 4.2 K, irradiated by microwave electromagnetic field with the frequency of 75 GHz, controlled by a computer which evaluates results of measurement. The Josephson array of SMU standard was manufactured by the National Institute for Standards and Technology USA. The array is mounted in cryoprobe (immersed in 100 l liquid Helium Dewar). Other parts of measuring system are the microwave power source (Gunn Diode GMI - 12 - 5CM), the bias source for the array (RMS cryosystem), the high accuracy digital voltmeter (HP model 3458A) and the oscilloscope (type 2225 Tektronics) for monitoring the l-V characteristics.

The microwave power source is supplying 40 mW of power at frequency in the range 70 to 100 GHz.The frequency is stabilised and known to accuracy of 1 part to 109. External time base on the cesium frequency standard is used. The electronic reference standards are available - DATRON 4910 and FLUKE 732B. They are used for dissemination of the voltage unit and for comparison measurement.

Contact

Eng. Peter Vrabček, Phd
phone: + 421 2 60294 360
e-mail: vrabcek@smu.gov.sk

Mr. Pavol Kopček
phone: + 421 2 60294 250
e-mail: kopcek@smu.gov.sk