Device and method for detecting faults in a shielded instrument

A fault detection device for an electrosurgical system, the fault detection device comprising:

• a shield continuity circuit configured to test electrical continuity across a shield of an electrosurgical instrument;
• a relay configured to control power to the electrosurgical instrument, the relay operable between a closed state for allowing power delivery and an open state for interrupting power;
• an indicator assembly comprising a first indicator element and a second indicator element, wherein the first indicator element is enabled when the relay is in the closed state and the second indicator element is enabled when the relay is in the open state;
• a current-to-voltage converter configured to convert a shield current to a voltage signal;
• an envelope detector configured to monitor a converted voltage signal and detect a peak shield current value;
• a shield current average detector configured to determine an average shield current value;
• a fault detection circuit configured to compare the peak shield current value and the average shield current value to one or more preset threshold values and to open the relay and illuminate the second indicator element if either of the peak shield current value or the average shield current value exceeds its respective threshold for a predetermined period of time;
• a timer configured to limit power interruption;
• and
• a battery-powered low battery detector configured to monitor a battery charge and illuminate the second indicator element upon detecting a low battery condition.