QUANTUM STANDARDS AND DIRECT QUANTITIES LABORATORY
     
DC current Scale of DC voltage from 10 to 1000 V DC Voltage unit and scale from 0 to 10 V
       
     
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:
Range Expanded uncertainty (k=2)
10 µA - 100 µA 10 µA/A
100 µA - 1 mA 10 µA/A
1 mA - 10 mA 10 µA/A
10 mA - 100 mA 10 µA/A
100 mA - 1 A 10 µA/A
1 A - 20 A 10 µA/A
      Calibration of digital ampermeters up to 10 A:
Range Expanded uncertainty (k=2)
10 µA - 100 µA 10 µA/A
100 µA - 1 mA 10 µA/A
1 mA - 10 mA 10 µA/A
10 mA - 100 mA 10 µA/A
100 mA - 1 A 10 µA/A
1 A - 20 A 10 µA/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
Mr. Dušan Rudohradský
phone: + 421 2 60294 239
     
                   
     
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.
Range Expanded uncertainty (k=2)
1 V 1.0 µV/V
10 V 0.6 µV/V
100 V 4.0 µV/V
1000 V 4.0 µV/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
Mr. Dušan Rudohradský
phone: + 421 2 60294 239
     
       
     
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
     
DC voltage standard with Josephson array		 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
Dr. Peter Vrabček Mr. Pavol Kopček
phone: + 421 2 60294 360 phone: + 421 2 60294 250
e-mail: vrabcek@smu.gov.sk e-mail: kopcek@smu.gov.sk