A Simple Methodology to Develop Bifilar, Quadrifilar, and Octofilar Calculable Resistors

• Main Authors: Alepth H. Pacheco-Estrada, Felipe L. Hernandez-Marquez, Carlos D. Aviles, Carlos Duarte-Galvan, Juvenal Rodríguez-Reséndiz, Humberto Aguirre-Becerra, Luis M. Contreras-Medina
• Format: Article
• Language: English
• Published: MDPI AG 2020-02-01
• Series: Applied Sciences
• Subjects: calculable resistor; frequency dependence; impedance metrology; reference standard; evanohm heat-treatment
• Online Access: https://www.mdpi.com/2076-3417/10/5/1595
• ISSN: 2076-3417

This paper describes the development of bifilar, quadrifilar, and octofilar Calculable Resistors (CRs). The research involves Evanohm-S and Isaohm wire heat treatment processes to achieve temperature coefficients less than 0.5 <inline-formula> <math display="inline"> <semantics> <mrow> <mi mathvariant="sans-serif">&#956;</mi> <mi mathvariant="sans-serif">&#937;</mi> <mo>/</mo> <mi mathvariant="sans-serif">&#937;</mi> </mrow> </semantics> </math> </inline-formula>/<inline-formula> <math display="inline"> <semantics> <msup> <mrow></mrow> <mo>∘</mo> </msup> </semantics> </math> </inline-formula>C in the CR&#8217;s wire resistance element, tests of different terminal&#8722;wire joining techniques, and construction aspects achieving a stability of less than 0.05 <inline-formula> <math display="inline"> <semantics> <mrow> <mi mathvariant="sans-serif">&#956;</mi> <mi mathvariant="sans-serif">&#937;</mi> <mo>/</mo> <mi mathvariant="sans-serif">&#937;</mi> </mrow> </semantics> </math> </inline-formula>/day. This kind of construction methodology has not been presented in detail in previous CR papers, and it is essential to accomplish the correct parameters of a CR. Without it, the development of a CR can take several months or even years. A comparison between CRs developed in this research and a CR from the Federal Institute of Metrology (METAS) in Switzerland was carried out. Measurement results between the 10 k<inline-formula> <math display="inline"> <semantics> <mi mathvariant="sans-serif">&#937;</mi> </semantics> </math> </inline-formula> octofilar CR and the METAS 1 k<inline-formula> <math display="inline"> <semantics> <mi mathvariant="sans-serif">&#937;</mi> </semantics> </math> </inline-formula> coaxial CR show an agreement better than 0.35 <inline-formula> <math display="inline"> <semantics> <mrow> <mi mathvariant="sans-serif">&#956;</mi> <mi mathvariant="sans-serif">&#937;</mi> <mo>/</mo> <mi mathvariant="sans-serif">&#937;</mi> </mrow> </semantics> </math> </inline-formula> through the audio-frequency range. Therefore, the octofilar CR can be used as an AC resistance reference with traceability to the quantum Hall resistance in DC.