A control system for use with an electrosurgical generator which delivers electrosurgical energy to tissue has a control module. The module includes a processor executing an algorithm. The algorithm has the steps of determining a sensed voltage value corresponding to a sensed voltage signal output by the electrosurgical generator and determining a sensed current value corresponding to a sensed current signal output by the electrosurgical generator. The algorithm has the steps of determining phase information corresponding to a phase shift between the voltage signal and the current signal and determining a characteristic related to the electrosurgical energy delivered to the tissue using the phase information, the sensed voltage value and the sensed current value.
