LOW-FREQUENCY QUANTITIES LABORATORY
     
POWER AND ENERGY OF AC CURRENT AT LOW FREQUENCY ROOT MEAN SQUARE (RMS) OF AC VOLTAGE AND CURRENT
       
     
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 at Low Frequency		 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
Mr. Ján Hanák Mr. Viliam Chovanec Mr. Peter Samuhel
phone: + 421 2 60294 358 phone: + 421 2 60294 304 phone: + 421 2 60294 304
e-mail: hanak@smu.gov.sk e-mail: chovanec@smu.gov.sk  
     
     
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 and 1 ) 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
Mr. Ján Hanák Mr. Viliam Chovanec Mr. Dušan Rudohradský Mr. Peter Samuhel
phone: + 421 2 60294 358 phone: + 421 2 60294 304 phone: + 421 2 60294 239 phone: + 421 2 60294 304
e-mail: hanak@smu.gov.sk e-mail: chovanec@smu.gov.sk