Multiple parameter fault detection in electrosurgical instrument shields

Abstract

A system and method for detecting faults within a shielded electrosurgical instrument are disclosed. The method includes sensing at least two of: an active voltage in the active electrode; a current in the active or return electrodes; or power in the electrosurgical instrument shield. The method also includes determining whether a power fault exists, wherein determining whether a power fault exists includes multiplying the sensed current and the sensed active voltage. The method also includes determining at least one of: whether one or more current faults exists; or whether a capacitance fault exists. The method also includes altering power delivery to the active electrode if any of the power fault, current faults, or capacitance faults exist.

1 . A method of detecting faults within a shielded electrosurgical instrument, the shielded electrosurgical instrument having an active electrode, the method comprising:
 sensing at least two of:
 an active voltage in the active electrode; 
 a current in the active or return electrodes; or 
 power in the electrosurgical instrument shield; 
   determining whether a power fault exists, wherein determining whether a power fault exists comprises multiplying the sensed current and the sensed active voltage;   determining at least one of:
 (a) whether one or more current faults exists; or 
 (b) whether a capacitance fault exists; and 
   altering power delivery to the active electrode if any of the power fault, current faults, or capacitance faults exist.   
     
     
         2 . The method of  claim 1 , further comprising determining whether a resistance fault exists, wherein determining whether a resistance fault exists comprises determining whether the expression W shield  R trip >V active   2  K scale  is true, wherein V active   2  is equal to the mean, squared, active electrode voltage, wherein W shield  is equal to the mean, real shield power, wherein R trip  is equal to the resistance below which a resistance fault is tripped, and wherein K scale  is equal to a scaling constant. 
     
     
         3 . The method of  claim 1 , wherein determining whether a current fault exists comprises determining whether the expression I shield   2 >I trip   2  is true, wherein I shield   2  is equal to the mean, squared shield current, and wherein I trip   2  is equal to a constant representing the square of current below which a current fault is tripped. 
     
     
         4 . The method of  claim 1 , wherein determining whether a capacitance fault exists comprises determining whether the expression V active   2 >I shield   2  Z fault   2  is true, wherein V active   2  is equal to the mean, squared, active electrode voltage, wherein I shield   2  is equal to the mean, squared, shield current, and wherein Z fault   2  is equal to a constant representing the square of the magnitude of the impedance at which a capacitance fault should be tripped. 
     
     
         5 . The method of  claim 1 , wherein determining whether a power fault exists comprises determining whether the expression (W shield >W trip ) is true, where W shield  is equal to the mean, real power in the shield and W trip  is equal to a constant representing the maximum average value of power above which a power fault may trip. 
     
     
         6 . A system for detecting faults within a shielded electrosurgical instrument, the shielded electrosurgical instrument having an active electrode, the system comprising:
 at least one sensor for sensing at least two of:
 an active voltage in the active electrode; 
 a current in the active or return electrodes; or 
 power in the electrosurgical instrument shield; 
   a processor configured to determine whether a power fault exists, wherein determining whether a power fault exists comprises multiplying the sensed current and the sensed active voltage, the processor further configured to determine at least one of:
 (a) whether one or more current faults exists, or 
 (b) whether a capacitance fault exists, 
   the processor further configured to alter power delivery to the active electrode if any of the power fault, current faults, or capacitance faults exist.   
     
     
         7 . The system of  claim 6 , wherein the processor is further configured to determine whether a resistance fault exists, wherein determining whether a resistance fault exists comprises determining whether the expression W shield  R trip >V active   2  K scale  is true, wherein V active   2  is equal to the mean, squared, active electrode voltage, wherein W shield  is equal to the mean, real shield power, wherein R trip  is equal to the resistance below which a resistance fault is tripped, and wherein K scale  is equal to a scaling constant. 
     
     
         8 . The system of  claim 6 , wherein determining whether a current fault exists comprises determining whether the expression I shield   2 >I trip   2  is true, wherein I shield   2  is equal to the mean, squared shield current, and wherein I trip   2  is equal to a constant representing the square of current below which a current fault is tripped. 
     
     
         9 . The system of  claim 6 , wherein determining whether a capacitance fault exists comprises determining whether the expression V active   2 >I shield   2  Z fault   2  is true, wherein V active   2  is equal to the mean, squared, active electrode voltage, wherein I shield   2  is equal to the mean, squared, shield current, and wherein Z fault   2  is equal to a constant representing the square of the magnitude of the impedance at which a capacitance fault should be tripped. 
     
     
         10 . The system of  claim 6 , wherein determining whether a power fault exists comprises determining whether the expression (Wshield>Wtrip) is true, where Wshield is equal to the mean, real power in the shield and Wtrip is equal to a constant representing the maximum average value of power above which a power fault may trip.