The DC-DC converters provide clean 36 VDC power suitable for battery powered control systems on railway equipment or rolling stock. For operation under the most harsh and demanding conditions, the units are fully sealed and enclosed to protect against moisture, shock, and vibration. Power from a battery or other source of 72 VDC nominal input is converted to a 36 VDC output regulated to 3%. Input and output isolation is provided. The units are designed with extremely rugged surge and transient suppression in addition to sustained over/under voltage protection. With a nominal nameplate rating of 240 Watts of output power, the DC-DC converters have an efficiency rated at >92%.