Higher plant efficiencies of future fossil-fired power stations require higher operational pressures and temperatures, leading to a design of high-stressed components nearer to the material limits, and presuppose in operation an improved steam generator control, especially for the feedwater Furthermore, a measuring system is required at the evaporator-end, which includes -besides pressure and temperature - also mass flows and steam content of a wet steam flow. A measuring system, which is suitable for this task, was tested in a laboratory and in a power station. It distinguishes itself by its compact and reliable design and uncomplicated handling, guarantees a simple interpretation of the measuring signals, and covers a large measuring range. Measuring system and measuring results are presented.