Over the past decade, significant areas of power semiconductor development have been: Increased electrical performance characteristics and optimization of the mix of same to meet specific application requirements. Improved packaging for better heat management and lower system cost. Thoughtful rating and characterization of devices specifically tailored to the needs of the control equipment designer. These developments, as would be expected, have precipated the wide acceptance and usage of power semiconductors in diverse areas of power control. The resultant benefit has been an ever improving system performance at a decreasing system cost.