A method for the design of holding electromagnets

The problem discussed is the optimum design of cylindrical holding electromagnets consisting of a ferromagnetic core, with stationary and movable portions, interlinking a coil of wire. These electromagnets are required to hold a switch or contact assembly in a given position as long as power is applied and to release it when power is removed. The electromagnet is not required to pull in the contact assembly; this is done by other means. It is desirable for the design method to proceed from the specified mechanical and electrical characteristics directly to the physical dimensions of the magnet without the use of trial-and-error methods.