Temperature Dependence of Zero Point in Force Transducers II: How to Account for the Effects of a Zero Balancing Resistor

Abstract

On the basis of findings discussed in a companion paper, two novel calculation procedures (iterative and analytic) for force transducer zero balancing without inducing temperature errors in the Wheatstone bridge circuit are introduced. The iterative method calculates a proper temperature compensating resistance without accounting for the effects of a zero balancing resistor and then determines the resistance of a zero balancing resistor. This process is repeated by computing subsequent ancillary resistance pairs until the thermal zero shift is small enough. The analytic solution uses bridge output ratio expressions at two different temperatures in the presence of a temperature compensating resistor and a zero balancing resistor in terms of the output ratios at the two temperatures in the absence of both resistors. It is found that the difference in output ratio between the two temperatures obtained by using the iterative method converges to zero as long as the temperature compensating resistor TCR is greater than the zero balancing resistor TCR. It is also found that the iterative solution is practically equivalent to the analytic solution in that the total resistance of temperature compensating resistors obtained from using the iterative method converges to the temperature compensating resistance calculated using the analytic solution.