DEVICE MEASURING ELECTRIC RESISTANCE Russian patent published in 2001 - IPC

FIELD: electrical engineering. SUBSTANCE: device is designed to measure electric resistance predominantly in milli- and macroohmic ranges of conductors, resistance of electric contacts and to test quality of electrodes for electric arc furnaces and of transformer windings by their resistance. Device has voltage source connected to one of leads intended for connection of measured resistance. Instrument shunt is placed between controlled voltage source and another lead intended for connection of measured resistance. Inputs of first differential amplifier are connected to instrument shunt and inputs of second differential amplifier are linked to leads intended for connection of measured resistance. Input of voltage division unit is connected to output of first differential amplifier. Key is placed in series with shunt. Input of storage and retrieval unit is connected to output of first differential amplifier and its output is linked to input of divider of voltage division unit. Counting input of reversible counter is linked to output of division unit. Control unit is connected to change-over input of counting direction of reversible counter and to control inputs of key and storage and retrieval unit. Voltage division unit comes in the form of voltage to number of pulses converter. EFFECT: increased accuracy and expanded measurement range of resistance to small values, enhanced efficiency and reduced overall dimensions of microohmmeters. 1 dwg