An improved, practical Burrows permeameter

Burrows permeameter, once the standard apparatus for magnetic testing and later abandoned due to its tedious operation, has been revived by applying electronics for automatic compensation using magnetometers as sensors of leakage flux. A study of basic sources of error; i.e., stray fields from compensation coils, indicates a potential accuracy of 0.1% or better at measured relative permeability of the order of 5000. To reduce errors due to eddy currents in the samples, sophisticated digital equipment was developed to control the magnetizing current.