Designing for switchgear insulation applications with GLASTIMAT

In January, 1946, The Laminated Plastics Co. started to make glass cloth reinforced polyester resin laminates for use in electrical insulation by the heavy electrical industry, replacing the canvas phenolic laminates widely used at that time. The new materials were about twice the cost of canvas phenolic since they used $2.00/lb. glass cloth, 40¢/lb. polyester resin and 04¢/lb. mineral fillers. They had, however, tremendously greater physical strength and vastly superior track resistance. With the introduction of chopped strand mat by Owens-Corning Fiberglas about 1948, it became possible to make laminates which were cheaper than canvas phenolic by using the 60¢/lb. glass mat in place of the $2.00/lb. glass cloth. The resultant product started to be sold in 1949 at 86¢/lb. (canvas phenolic was $1.00/lb.). This new product gained wide acceptance in the heavy electrical insulation market because of its superior mechanical and electrical properties. The sheet stock was cut up into various sizes and shapes and, using metal angles and nuts and bolts, combination structural insulating systems were made.