Control circuit of ground fault circuit interrupter (GFCI)

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 (N1) used for transforming the flux change into an influence potential output, a lead of said load connection circuit (20) going across said detection winding (N1);
• 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 (N1);
• 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.