DRD Series Converters. The DRD series from Chinfa are DC-DC DIN Rail mountable converters with short circuit protection. They have a 4:1 wide input voltage range and internal input filter. Features and Benefits. 4:1 wide input range. Short circuit protection. Internal input filter. Remote on/off. Low profile. Product Application Information. Building control systems. Factory automation. Industrial controls. The DRD series of dc dc converters have been designed for powering commercial and industrial grade electronic circuits.