Abstract :
CONSIDERING the wide range of types of electric circuit, it is at once evident that an equally wide variety of properties, — electrical, mechanical, and thermal, — is demanded for their insulation. Experiment and research directed toward improvements in insulation, therefore, have an almost unlimited field of opportunity. An enormous mass of experimental data from experienced investigators has already been presented. So wide is the problem, however, that these data have not only failed to place the design of insulation on a satisfactory engineering basis, but still leave it as probably the most important problem confronting the electrical engineer of today. The life of electric equipment is often limiten to that of its insulation, and the consequences of failure are usually disastrous and costly.