Accuracy Measures of the Four Arm Bridge of Broadly Variable Resistances Part 1. Backgrounds, General Case of Four Variable Arms

摘要

After short introduction the open circuit output voltage of four-arm resistance (4R) bridge supplied by current or voltage is given. Normalized forms of its current to voltage and voltage to voltage open circuit transmittances are defined. The simplified description of accuracy of the broadly variable resistance by instantaneous, limited and random errors of its initial value and of increment is introduced. Borders (the worst cases) of the field of its possible error values are found for constant values of both this limited errors. Accuracy measures of current to voltage transmittance, i.e. instantaneous and limited errors and mean square random measures (probabilistic errors or uncertainties) are discussed in detail for general case of arbitrary variable all bridge arms. Basic formulas together with their equivalents for voltages transmittance are completed in the Table 1. Literature is included. Accuracy description of other common in practice particular cases of the 4R bridge and example of its application for temperature sensors Pt 100 are described in the part 2. Final conclusions are also there.