The device (10) has controllable high frequency (HF) generator (18) to generate HF power in incision operating mode during incision phase in which an electrode placed in moist tissue milieu evaporates surrounding fluid, and in cutting operating mode during cutting phase in which HF discharge at electrode (14) is maintained. A sensor device (26) is provided to recognize occurrence of evaporation and to start HF discharge. The HF generator is switched from incision operating mode to cutting operation mode, upon detection of start of HF discharge. An independent claim is included for method for operating electrosurgical device for providing instrument with electrical power.
