Abstract: A hermetic enclosure assembly having a metal header cover with interior and exterior portions and defining a plurality of apertures. A header body of rigid plastic material is adhered to and fills a substantial part of the interior portion of the header cover. A plurality of conductive leads protrude through the apertures, and bushings surround the conductive leads at the interior and exterior portions of the header cover where the pins protrude. A metal header casing is adhered to the metal header cover such that the interior portion of the header cover is completely enclosed. The assembly provides a minimum of plastic located exteriorly of the assembly and a maximum located interiorly.

Abstract: A process for making an encapsulated electrical insulation system such as a transformer which includes a porous fiber material filling. The system is vacuum baked at a temperature range of 100.degree. C. to 155.degree. C. for at least four hours, and is then vacuum impregnated with a mixture of a modified bisphenol A epoxy resin hardener comprising various acid anhydrides plus promoters. Pressure is then applied to the system of 1,000 psi. of nitrogen at 80.degree. C. for 2 to 12 hours. Thereafter, the temperature is increased to 110.degree. C. for 2 to 12 hours. The system is then cured at 135.degree. C. for approximately 12 to 24 hours. To minimize corona, shields are placed in selected portions of the transformer, the shields having edges formed into radii ends to avoid points at which corona would normally tend to concentrate. Also, the transformer is wound using ultra-clean components to obtain a transformer package that is free from impurities prior to impregnation.

Abstract: An emergency standby power system for automatic transfer from utility power to a battery powered inverter when a normal source of utility power is interrupted to a given load, and for automatic re-transfer to utility power when it is restored. The inverter includes SCR circuitry whereby commutation failure during start-up and shut-down is prevented by applying power to the inverter prior to the application of the gate drive during start-up, and removing power from the inverter prior to the removal of the gate drive during shut-down. Further, the control circuitry ensures that the first SCR gated on will operate for a complete one-half cycle, thereby fully charging the commutating capacitor for reliable commutation off of the first SCR before turning on the second SCR. The control circuitry also permits the inverter to start up even if it is presented with a short circuit and operate without damage.