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