Heavy-duty precision wire-wound alternating-current resistor and method of making

摘要

A heavy-duty precision wire-wound alternating-current resistor comprises a capsule filled with a liquid dielectric formed of a low-viscosity liquid perfluorinated organic compound. Within the capsule of the resistor there is arranged a sectionalized bobbin made from a dielectric material chemically resistant to the liquid perfluorinated organic compound. The sectionalized bobbin carries a resistance element with a clearance therebetween dimensioned so as to exceed by at least an order of magnitude the change in the bobbin diameter due to the magnitude of thermal expansion of the material of the sectionalized bobbin in order to provide the circulation of the liquid dielectric therein. A method of making said heavy-duty precision wire-wound alternating-current resistor comprises the steps of coating the sectionalized bobbin with a layer of a sublimable substance; winding a high-resistance insulated wire, forming the resistance element, onto the sectionalized bobbin; subsequently removing the layer of said sublimable substance by means of vacuum treatment, providing thereby said clearance between the sectionalized bobbin and the resistance element; and filling the capsule of the resistor with the liquid dielectric.