Patent ID: 8264814

Claim:
A downhole tool ( 10 ) comprising: a first end ( 10 A); a second end ( 10 B) releasably coupled to said first end ( 10 A); an actuator ( 145 ) coupled to said first and second ends ( 10 A, 10 B) and arranged for parting said second end ( 10 B) from said first end ( 10 A) upon energization by an electrical current; a conductive electrical path between said first end ( 10 A) and said second end ( 10 B), said electrical path defining an input node ( 104 ) at said first end ( 10 A); a first switch element ( 201 ) electrically connected in said conductive electrical path, said first switch element ( 201 ) arranged to connect said actuator ( 145 ) to said input node ( 104 ) upon application of negative voltage of a first predetermined level at said input node ( 104 ); and a second switch ( 202 ) element electrically connected in said conductive electrical path, said second switch element ( 202 ) arranged to connect said actuator ( 145 ) to said input node ( 104 ) upon application of positive voltage of a second predetermined level at said input node ( 104 ); whereby said first and second switch elements ( 201 , 202 ) allow said second end ( 10 B) to be parted from said first end ( 10 A) upon application of either negative or positive voltage at said input node ( 104 ).