There is described herein an electrosurgical system for applying electrical energy to a target site on or within a patients body. The system includes a high frequency power supply, an instrument coupled to the power supply including a resistor defining a resistor value and a probe identification device coupled to the power supply. The probe identification devie is arranged to recognise the resistor value for the instrument. A corresponding method of operating an electrosurgical system and an electrosurgical probe are also provided.
