A DC Permeameter for Ring Specimens

The construction of a permeameter for measuring magnetic parameters of a ring specimen is presented. The principle of this permeameter is based on the flux transmission from the specimen to an auxiliary core fixed in the bottom of a coaxial-cylindrical cavity. The flux change in the specimen can be measured from the auxiliary core, on which there is an equivalent measuring coil of 1-1000 turns. A special design reduces the resistances of the cavity body and its cover and the contact resistance between them to the order of 10-6 ¿, so that the time constant of the flux transmission circuit is up to 100 s. The error of the flux transmission is then about 1 percent. Combined with various measuring systems, the permeameter can be used to measure magnetization curve, hysteresis loop as well as all dc magnetic parameters rapidly. A specimen with very small cross section or very low induction can be easily tested with this apparatus.