Patent ID: 7514936

Claim:
An electrical circuit for averting damage in the event of an abnormal change in an electrical load to which an RF power source supplies power, comprising: an RF power source having an RF output to which it supplies RF power, the RF output being adapted for connection to an electrical load; a reflected RF power sensor electrically coupled to the RF output of the RF power source, wherein the reflected RF power sensor produces a reflected power sensor signal responsive to the reflected RF power at the RF output of the RF power source; a threshold detector circuit connected to receive the reflected power sensor signal from the reflected RF power sensor, wherein the threshold detector circuit detects when the rate of change of said reflected power sensor signal exceeds a first threshold; and a power control circuit, responsive to the threshold detector detecting that the rate of change of the reflected power sensor signal has exceeded said first threshold, that reduces the power being supplied by the RF power source to the RF output.