Absolute Measurement of Current Dependence in DC Resistors by a Double Current Method

A double current method is presented for absolute measurements of the current dependence (power variation) of dc resistors. Based on the resistance measurement principle of a direct current comparator (DCC), and adding another DCC-based extender with a turn ratio 1:1, the testing current in resistors to be tested is accurately doubled. Through three comparative measurements with two reference standard resistors connected in series as Kelvin resistive bridge inner arms, the change of resistance caused by doubling the currents is measured. Cyclically done, absolute measurement of current or power factor is realized. Examples of the current dependence of some commercial low-temperature coefficient 1 Ω standard resistors are given using the presented method and their results are analyzed.