Substitution of Laminated Low-Carbon Steel for Silican Steel in the Cores for Wire Spring Relays

This article describes the analytical and laboratory studies undertaken to determine if low-carbon steel could be substituted for the more expensive 1 per cent silicon steel in the cores of general-purpose wire spring relays. Not only is this silicon steel more costly, but its hardness characteristics are such that tool maintenance for man ufacture is an appreciable item. It was found that this substitution can be made without degrading the performance of these relays, provided the new core is made up of Itvo laminations. When two laminations are used, the eddy current time constant of low-carbon steel matches that of the silicon steel. This is necessary to achieve the fast operate and release times now obtained and to permit satisfactory operation of present circuits when the substitution is made. This substitution will result in substantial annual manufacturing savings for the general-purpose relays. These savings could be further increased if use of the new core could be extended to other, more special, relays of the wire spring relay family. These applications are now under study.