UNIDO-KRISS training program

in metrology (workshop 2)

LF Voltage/Current Standards & Calibration of the TVC/TCC

Sung-Won KWONCenter for Electricity & MagnetismDivision of Physical MetrologyPhone : +82 42 868 5155Fax : +82 42 868 5018E-mail: swkwon@kriss.re.kr

The AC voltage and current standards at low frequency below 1 MHz are derived from the DC voltage and current standards which are traceable to the Josephson voltage standard. The standards are depends on the use of such instruments which have ideally the same response to both DC and AC quantities. Such instruments are called AC-DC transfer instruments. AC-DC transfer measurement is based on RMS (root mean square) value. The equivalence of DC and AC quantities in AC-DC transfer device is achieved when they produce the same electrical power which in turn must be equivalent to mechanical power.

Thermal AC-DC transfer device such as thermal voltage converter (TVC) and thermal current converter (TCC) are most widely used from the years of 1950. The general scope of AC voltage and current standards are in the range of 1 mV to 1 kV below 1 MHz and range of 1 mA to 100 A below 100 kHz respectively. They are established and disseminated by the use of the TVC for AC voltage and TCC for AC current.

Brief introduction of the low frequency voltage and current standards, and the calibration procedure and uncertainty evaluation of the TVC and TCC are presented.

References

[1] S.W. Kwon, et al, “Development of a two channel automatic AC-DC voltage transfer difference measurement system at KRISS”, Digest of the IMEKO TC-4 conference, Naples, Italia, 1998.

[2] “Guide to the expression of uncertainty in measurement,” ISO 1993. [3] S.W. Kwon, “Fabrication of planar multi-junction thermal converter”, J. of Korean

Sensor Society, vol.4, No.4, pp.17-24, 1996.[4] S.I. Park, S.W. Kwon, et al, “Micro-machined thin-film multi-junction thermal

converters at KRISS”, CPEM 2002 digest, p.32-33, Ottawa, Canada, 2002.[5] J.S. Kim, S.W. Kwon, et al, “A planar Bi-Sb multi-junction thermal converter with

small AC-DC transfer differences”, IEEE Trans. IM., vol.51, No.1, p.115-119, 2002.

[6] Y.H. Lee, S.W. Kwon, et al, “Improved thin-film multi-junction thermal converters for low-frequency performance”, J. of Korean Physical Society, vol.48, No.6, p.1574-1578, 2006.

[7] I. Budovsky, S.W. Kwon, et al, “APMP international comparison of AC-DC transfer standards at the lowest attainable level of uncertainty”, IEEE Trans. IM., vol.54, No.2, p.795-798, 2005.

[8] I. Budovsky, “Algorithm and uncertainty of AC-DC transfer measurements”, Proc. Metrology Society of Australia. P.82-88, Biennial Conference, Gold Coast, Australia, Oct., 2001.