A self-contained electronic steam trap drains condensate from a steam system. The steam trap includes a drain pipe adapted for fluid communication with a steam supply system. Pressure and temperature sensors measure pressure and temperature in an internal passageway of the steam trap. A condensate discharge valve is disposed at or upstream of an output port of the drain pipe. The condensate discharge valve is controlled based on the measured pressure and temperature and a calculated steam saturation temperature. Both a cycling mode and a regulation mode of automatic valve operation are described.