Patent ID: 7626788

Claim:
A control circuit of a ground fault circuit interrupter (GFCI) with creepage protection, said control circuit comprising: a load connection circuit ( 20 ), used to electrically connect a power end line and a load, transferring AC thereof; a creepage detection circuit ( 15 ), having a detection winding (N 1 ) used for transforming the flux change into an influence potential output, a lead of said load connection circuit ( 20 ) going across said detection winding (N 1 ); a trip circuit ( 23 ), having a trip winding (J), being used for current transformed into electromagnetism power; and a trip control circuit ( 16 ) electrically connected between said creepage detection circuit ( 15 ) and said trip winding and being used to compare an input electrical signal with a predetermined value, and while the input electrical signal being larger than the predetermined value, an output end of said trip control circuit ( 16 ) exporting effective electrical level; a self-diagnosis current generation circuit ( 21 ), coupled to said load connection circuit ( 20 ) on at least one end, and a lead of which goes across said detection winding (N 1 ); a self-diagnosis display circuit ( 17 ), used for display of whether the creepage protection function is in good condition; a first switch duct ( 22 ), having at least two connection ends and a control end for controlling said connection end to be electrically connected or to be disconnected, with said control end being coupled to said output end of said trip control circuit ( 16 ), and said connection ends being respectively connected with said trip circuit ( 23 ) and said self-diagnosis display circuit ( 17 ), wherein one of said trip circuit ( 23 ) and self-diagnosis display circuit ( 17 ) is electrically connected when the input AC in positive half-cycle, while another is electrically connected when the input AC in negative half-cycle; a self-diagnosis terminal circuit ( 18 ) for disconnecting said self-diagnosis display circuit ( 17 ) after display is completed, wherein said self-diagnosis terminal circuit ( 18 ) includes a transistor (Q); said self-diagnosis display circuit ( 17 ) has an optoelectronic couple (OC) with an output end electrically connected to a second switch duct (SCR2), said second switch duct (SCR2) having at least two connection ends and a control end coupled to said output end of said OC for controlling said connection ends being electrically connected or disconnected; and wherein said transistor (Q) has a base electrode connected to one connection end of said second switch duct (SCR2), and wherein another connection end of said second switch duct (SCR2) is grounded.