Circuit interrupter with ground fault current transformer
A circuit interrupter including a first set of separable contacts, a second set of separable contacts, a first operating mechanism structured to open the first set of separable contacts, a second operating mechanism structured to open and close the second set of separable contacts, and an electronic trip unit including a routine structured to detect a fault condition and a type of the fault condition, to control the second operating mechanism to open the second set of separable contacts in response to detecting a first type of fault condition, and to control the second operating mechanism to close the second set of separable contacts a predetermined amount of time after controlling the second operating mechanism to open the second set of separable contacts.
1. A circuit interrupter comprising:
a first line conductor;
a second line conductor;
separable contacts;
an operating mechanism structured to trip open the separable contacts;
a trip circuit structured to cause the operating mechanism to trip open the separable contacts;
a ground fault current transformer having an oblong shape and being disposed around the first and second line conductors, wherein the ground fault current transformer is structured to sense a ground fault current from current flowing through the first and second line conductors; and
a processor structured to detect a ground fault based on the ground fault current sensed by the ground fault current transformer and to output a signal to cause the trip circuit to cause the operating mechanism to trip open the separable contacts in response to detecting the ground fault,
wherein the ground fault current transformer includes a first winding and a second winding,
wherein the first winding includes a first number of turns spread along a first portion of a perimeter of a core of the ground fault current transformer,
wherein the second winding includes a second number of turns spread along a second portion of the perimeter of the core,
wherein the first portion of the perimeter of the core that the turns of the first winding are spread along is a majority of the perimeter of the core, and
wherein second portion of the perimeter of the core that the turns of the second winding are spread along is less than a majority of the core.
2. The circuit interrupter of claim 1 , wherein the ground fault current transformer has an outer length, an outer width, and a thickness; wherein the outer length is greater than the outer width; and wherein the thickness is within a range of about 7 mm to about 8 mm.
3. The circuit interrupter of claim 2 , wherein the thickness of the ground fault current transformer is about 7.5 mm.
4. The circuit interrupter of claim 2 , wherein the outer length of the ground fault current transformer is about 48.5 mm and the outer width of the ground fault current transformer is about 17 mm.
5. The circuit interrupter of claim 2 , wherein the ground fault current transformer has an opening having an inner length and an inner width; and wherein the inner length is about 36.5 mm and the inner width is about 5 mm.
6. The circuit interrupter of claim 1 , wherein the first and second line conductors are busbars.
7. The circuit interrupter of claim 1 , wherein the processor is structured to detect the ground fault based on the output of the first winding; and wherein the processor is structured to use the second winding to perform a ground fault test.
8. The circuit interrupter of claim 1 , wherein the first winding has a first number of turns; wherein the second winding has a second number of turns; and wherein the first number of turns is at least 80 times the second number of turns.
9. The circuit interrupter of claim 1 , wherein second portion of the perimeter of the core is proximate one of the first and second line conductors.
10. The circuit interrupter of claim 1 , further comprising:
a sensing circuit electrically coupled between the first winding and the processor,
wherein the sensing circuit is structured to convert an output of the first winding for use by the processor to detect the ground fault.
11. The circuit interrupter of claim 1 , further comprising:
a test circuit electrically coupled between the second winding and the processor,
wherein the test circuit is structured to receive a self-test signal from the processor and to apply a signal to the second winding in response to receiving the self-test signal.
12. The circuit interrupter of claim 1 , further comprising:
a first line terminal electrically connected to the first line conductor; and
a second line terminal electrically connected to the second line conductor,
wherein the separable contacts include first separable contacts and second separable contacts, and
wherein the ground fault current transformer is disposed around the first and second line at portions of the first and second line conductors electrically connected between the first and second line terminals and the first and second separable contacts, respectively.
13. A circuit interrupter comprising:
a first line conductor;
a second line conductor;
separable contacts;
an operating mechanism structured to trip open the separable contacts;
a trip circuit structured to cause the operating mechanism to trip open the separable contacts;
a ground fault current transformer having a first winding and a second winding and being disposed around the first and second line conductors, wherein the ground fault current transformer is structured to sense a ground fault current from current flowing through the first and second line conductors using the first winding; and
a processor structured to detect a ground fault based on an output of the first winding and to output a signal to cause the trip circuit to cause the operating mechanism to trip open the separable contacts in response to detecting the ground fault, and wherein the processor is structured to use the second winding to perform a ground fault test,
wherein the first winding includes a first number of turns spread along a first portion of a perimeter of a core of the ground fault current transformer,
wherein the second winding includes a second number of turns spread along a second portion of the perimeter of the core,
wherein the first portion of the perimeter of the core that the turns of the first winding are spread along is a majority of the perimeter of the core, and
wherein second portion of the perimeter of the core that the turns of the second winding are spread along is less than a majority of the core.
14. The circuit interrupter of claim 13 , wherein the first winding has a first number of turns; wherein the second winding has a second number of turns; and wherein the first number of turns is at least 80 times the second number of turns.
15. The circuit interrupter of claim 13 , wherein second portion of the perimeter of the core is proximate one of the first and second line conductors.
16. The circuit interrupter of claim 13 , further comprising:
a sensing circuit electrically coupled between the first winding and the processor,
wherein the sensing circuit is structured to convert an output of the first winding for use by the processor to detect the ground fault.
17. The circuit interrupter of claim 13 , further comprising:
a test circuit electrically coupled between the second winding and the processor,
wherein the test circuit is structured to receive a self-test signal from the processor and to apply a signal to the second winding in response to receiving the self-test signal.