A Four-Terminal Current Shunt with Calculable AC Response
Owen B. Laug, T. M. Souders, Bryan C. Waltrip
The design of a 0.1 Ohm, four-terminal current shunt with calculable frequency dependence up to 1 MHz is described. It is intended for use as a standard for current measurements up to 10 A rms with the primary purpose of being able to tie alternating-current measurements to direct-current measurements. The shunt is of the bifilar flat-strip configuration where the effects of self-inductance, skin effect, capacitance, dissipation factor, and eddy-current losses were considered. Contributions of the individual effects, where applicable, were determined by calculation based on geometry and corroborated by differential measurements and finite-element field simulations. The uncertainties due to dimensional and electrical measurement tolerances were computed as well. In addition to the calculable aspects of the shunt this technical note provides assembly details of the shunt based on the mechanical drawings made available in the appendix. The practical issues of measuring 4-terminal shunts with emphasis on dealing with common-mode potentials are discussed. The thermal properties of the current shunt are presented together with some suggestions on reducing the power coefficient of resistance.
0.1 ohm shunt, 4-terminal shunt, ac resistor, bifilar shunt, calculable shunt, current shunt
, Souders, T.
and Waltrip, B.
A Four-Terminal Current Shunt with Calculable AC Response, Technical Note (NIST TN), National Institute of Standards and Technology, Gaithersburg, MD, [online], https://doi.org/10.6028/nist.tn.1462, https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=31690
(Accessed October 2, 2023)