Comparison of insulating varnishes

Solvent varnishes have been used on electrical equipment with excellent results for many years. They combine low cost, easy handling and excellent electrical and thermal aging properties. The growth of regulatory institutions during the first half of the 1970´s and legislation concerning the toxicity and safety of organic solvents led manufacturers to search for alternate materials. Two systems, quite different in makeup, were formulated. Both systems have been in use for 5–10 years. We have obtained a good deal of information on actual field usage of these systems. This paper reports on handling and use problems experienced, with water and solventless varnishes, and gives some processing data comparing the three systems.