Current leakage control for electrosurgical generator

Abstract From the Canadian patent

A current leakage control circuit (115) regulates the output power of an electrosurgical generator (20) to limit the amount of leakage current. The leakage current is monitored with a differential transformer (90) which has the output lead (30) and return leads (80) of the electrosurgical generator (20) as first and second winding (96). A third or sense winding (100) produces a control signal whenever the currents in the output and return leads (30 80) are not equal, thus indicating current leakage. The control signal is compared to a predetermined maximum safe level of leakage current. If this predetermined level is exceeded a power control, feedback loop of the eletrosurgical generator …