Microprocessor-based resistance measurement

The paper deals with microprocessor-based resistance measurement of electrical RL circuits by sampling values of the current and voltage. Special attention is paid to the relation between the time required for this measurement and the accuracy attained. This is a problem associated with circuits having a very high electrical time constant, such as windings of large transformers or superconducting coils. The suggested method permits shortening of the required resistance measurement time, which in turn realizes a significant overall time saving. In addition, it permits overcoming essential measurement errors which may occur when the test is performed during a thermal transient. Different measurement errors are analyzed and a statistical method which leads to significant improvement of the result is presented.