Measurement of AC magnetic properties using a phase-sensitive voltmeter and microprocessor

A method is described whereby coreloss, permeability, and reactive power can be derived from voltage and current measurements made on the windings of a test core. By measuring in-phase and quadrature components of primary voltage and current, an equivalent circuit is obtained for the magnetic core and its windings. The apparent parallel inductance and resistance attributed to the test specimen are used to derive its magnetic parameters. An instrument is described which has been used to measure a variety of specimens at induction levels from a few gausses to near saturation and at frequencies up to 10 kHz. A comparison is presented showing correlation between this instrument and a modified Hay bridge (Deiterly Bridge)