D. c. breakdown of thermoplastic materials

With High Voltage Engineering Corporation's development of the Insulating Core Transformer power supply, the use of insulation at high levels of d.c. gradient became mandatory. Very little information is available as to the ultimate d.c. dielectric strength of insulating materials, and, as standard measurements (ASTM-D149) are not applicable in these areas, a program was initiated to obtain data on various thermoplastic materials.