Equivalent Circuit Expression of Retentivity in Electromagnet

An electric equivalent circuit was derived from measurements of the retentivity decay characteristics of electromagnets (solenoids), and the relationship between spring strength and oscillation-free magnetizing currents was studied. Several time constants related to the decay were in evidence; two of these could be determined with precision, allowing formulation of an equivalent circuit with two RC loops in series. The R and C values in these loops are related to the solenoid attractive force, shape, material used, temperature, and surface contact area.