A 200-Hz to 30-MHz computer-operated impedance/admittance bridge (COZY)

For the past few yean the development of ferromagnetic components, particularly for long-haul transmission systems, has relied heavily on large numbers of highly accurate impedance measurements made on a computer-operated impedance/admittance bridge (COZY) developed especially for this work, COZY's accuracy and speed enable a level of component development not otherwise possible. COZY automatically measures complex impedance, temperature coefficients of complex impedance, and disaccommodation factors of ferromagnetic materials, providing accuracies of ±0.05 percent for inductance, ±50 microradian for loss angle, and ±10 parts per million for the small impedance changes associated with determinations of temperature coefficients and disaccommodation factors, COZY is easy to use and makes a measurement in 10 to 20 seconds. Also, the calibration of the bridge unit's capacitance and conductance standards can be checked automatically. Though developed primarily for ferromagnetic component work, COZY is a general-purpose bridge; it measures inductance, capacitance, resistance, and conductance over wide impedance ranges at frequencies between 200 Hz and 30 MHz. This paper describes COZY's hardware, software, and performance.