Determination of the pressure coefficients of electronic voltage standards

Electronic voltage standards (EVSs), based on Zener-diode reference element s, are widely used as standards to maintain a local representation of the v oltage unit and as transfer standards for comparisons between local voltage reference standards at different locations. In order to make optimum use o f such standards, it is important that individual units be characterised fo r the effects of external influence factors so that the appropriate correct ions can be applied. Ambient atmospheric pressure affects the outputs of so me EVSs. An experimental set-up to measure the pressure coefficient of an E VS is described and data showing the correlation between pressure and outpu t voltage presented. Pressure coefficients calculated for the 10V outputs o f a range of commercial electronic voltage standards are also presented.