In a steam engine, thermodynamic energy in the form of vapor pressure from steam generators is converted into mechanical energy. This can be used further downstream in the process to generate electricity or to power machinery and vehicles. A steam power plant consists of a heat source for generating steam, a turbine or steam engine with a generator, and a cooling device for condensing the exhaust steam.

The SM-400 trainer contains the main components of a steam power plant: a gas-fired steam boiler, a single-cylinder piston steam engine with a generator, a condenser, a feed water tank, and a feed water pump. The steam boiler generates water steam and supplies it to the piston steam engine. A piston and a crank mechanism convert the energy from the steam into mechanical energy. A generator in the form of a DC motor generates electricity from the mechanical power. Four light bulbs are used as consumers of the resulting electrical energy.

The exhaust steam is condensed in a water-cooled condenser. Safe operation is ensured by safety devices that monitor the boiler temperature and a safety valve. Sensors record the temperature, pressure, and flow rate at all relevant points. The measured values can be read on displays. Current and voltage from the generator are measured and displayed in the experimental unit.