CONTROL CIRCUIT OF GROUND FAULT CIRCUIT INTERRUPTER (GFCI)

• US 20080022153A1
• Filed: 07/24/2007
• Published: 01/24/2008
• Est. Priority Date: 07/24/2006
• Status: Active Grant

• Current Assignee: Suzhou Songbao Electric Co., Ltd.
• Original Assignee: Suzhou Songbao Electric Co., Ltd.
• Inventors: Shu, Fudong, Wang, Kunliu, Zhang, Kuiyang
• Granted Patent: US 7,626,788 B2
• Time in Patent Office: Days
• US Class Current: 714/30
• CPC Class Codes: H02H 3/335 the main function being self testing of the device

Abstract

A control circuit of Ground Fault Circuit Interrupter (GFCI), includes a load connection circuit used to connect power end and load end while transferring AC thereof, a creepage detection circuit, a trip control circuit and a trip circuit, and further includes a self-diagnosis current generation circuit, a self-diagnosis display circuit and a first switch duct. When the input AC in positive half-cycle, one of the said trip circuit and the self-diagnosis display circuit is electrically connected, while another should be electrically connected while the input AC in negative half-cycle, so without manpower-provided simulated signal, the control circuit of GFCI can be self diagnosed of creepage protection function, for the feedback of the stand or fall circs in time.

Claims

1. 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 end 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 J, 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; and

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.

2. A control circuit of according to claim 1, further comprising 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.

3. A control circuit of according to claim 2, wherein 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 at least having 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.

4. A control circuit according to claim 3, further comprising an indication circuit for the end of life (19), which is connected between said two connection ends of said second switch duct SCR2.

5. A control circuit according to claim 3, 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.

6. A control circuit according to claim 5, wherein said self-diagnosis current generation circuit (21) as includes an LED D6 and a resistor R9, and wherein said transistor Q also has a collector and an emitter, series of said LED D6 and resistance said resistor R9 electrically connected to the load connection circuit (20) at one end, and electrically connected to said collector or said emitter of said transistor Q.

7. A control circuit according to claim 1, wherein said self-diagnosis display circuit (17) includes a resistor R6, a capacitor C8, an LED D7 and an optoelectronic couple (OC), the series of resistor R6, capacitor C8 and LED D7 being electrically connected between said two connection ends of said first switch duct (22), and the OC being paralleled with the two ends of said LED D7.

8. A control circuit according to claim 1, wherein an LED D6 is electrically connected in said trip circuit (23).

9. A control circuit according to claim 4, wherein said indication circuit for end of life (19) includes a resistor R10 and an LED LED1, the series of said LED LED1 and said resistor R10 being electrically connected between the two connection ends of said second switch duct SCR2, while a capacitor C7 is paralleled to said two connection ends of said second switch duct SCR2.