This series drop 3-phase AC power supply through rectifier transformer and then get 220V DC through single-phase (3-phase) rectifier bridge unit. Each cabinet consists of auto air switch, rectifier transformer, rectifier unit, DC contactors, etc., The circuit has safe protections like short circuit and over voltage.lt has advantages of simple structure, compact, light weight, reliable performance and convenient for repair.
　　The rectifier transformer will be equipped with outside cover when the rated capaaty of cabinet is more than 19 kW. The improved type has no rectification transformer, for it can rectify 3-phase AC power through bridge type rectifier directly and thus get DC..