Head of the laboratory Dr. Rimantas Miškinis,
phone +370 5 2620194
The mission of the Electrical standards laboratory is the following:
- to conduct scientific research in the field of electrical units;
- to realize the value of the unit of voltage, the volt (V) and the value of the unit of resistance, the ohm (Ω);
- to maintain the traceability of the magnitudes realized to the International system of units SI and to disseminate them to Lithuanian state and scientific establishments, legal and personal bodies by means of calibrating their measurement equipment;
At present time, the laboratory maintains a primary standard of voltage and a secondary standard of resistance. The secondary standard of resistance has been recognized as a national standard.
Operating principles of the standard and traceability. The operation of the “Hypres” primary standard of voltage is based upon the Josephson effect. The Josephson effect is a phenomenon of superconductivity, which relates the voltage of the Josephson junction to the frequency of electromagnetic radiation in terms of the ratio between fundamental physical constants – the Planck constant and the electron charge. The signal of precise 10 MHz frequency comes from an atomic clock of the Time and Frequency Standard Laboratory. The Josephson junctions connected in series allows realizing the standard values of voltage in the range 0 – 10 V. The standard value of voltage realized is transferred to the secondary Zener voltage standards and other laboratory‘s equipment by means of direct comparison.
The standard of resistance is of the secondary level. The secondary standards of 1 Ω ir 10 kΩ make up the groups standard of resistors. Using the resistance measurement bridges, a set of high precision decade standard resistors, which allows reproducing any resistance value in the range from 0,001 Ω up to 1 TΩ, is calibrated against the secondary standards. The ambient conditions required are maintained by the air conditioning system, whereas the temperature of the standard resistors and those being calibrated is maintained by the oil baths and air thermostats.
Traceability of the resistance value realized to the SI system is ensured by regular calibration of the secondary resistance standard against a quantum Hall system at a foreign metrology laboratory (e. g., CMI, PTB, or NPL). The values of direct and alternate voltage realized are traceable to the laboratory’s primary Josephson standard of voltage, which realizes the unit of voltage of the SI system.