Fault current interrupter
AssigneeGeneral Electric Company
InventorEdward K. Howell
Life of this patent
Estimating the term…
Abstract
A fault current interrupter is provided by the parallel combination of a positive temperature coefficient resistor and a voltage dependent resistor connected across a pair of separable contacts to permit the interruption of current without the occurrence of arcing between the contacts when the contacts first become separated. The positive temperature coefficient resistor is selected to have a relatively low resistance at room temperature and a substantially higher resistance at higher temperatures. This allows the current to transfer away from the contacts through the positive temperature coefficient resistor until the voltage across the voltage dependent resistor causes the voltage dependent resistor to become conductive and thereby transfer the current away from the positive temperature coefficient resistor.
Claims5
A fault current interrupter comprising:
- a pair of separable electric contacts arranged for interrupting current flow through an electric circuit;
- and
- a positive temperature coefficient resistor electrically connected in parallel across said electric contacts for transferring said current through said positive temperature coefficient resistor when said electric contacts first become separated, said positive temperature coefficient resistor including a layer of material having voltage dependent properties to increase the rate at which said positive temperature coefficient material reached a predetermined temperature.
A fault current interrupter comprising:
- a pair of separable electric contacts arranged for interrupting current flow through an electric circuit;
- and
- a positive temperature coefficient resistor electrically connected in parallel across said electric contacts for transferring said current through said positive temperature coefficient resistor when said electric contacts first become separated,
- said positive temperature coefficient resistor comprising a material having grain boundaries and wherein said grain boundaries include a material having voltage dependent properties to increase the rate at which said positive temperature coefficient material reaches a predetermined temperature.
A fault current interrupter comprising:
- a pair of contacts and a resistor connected across said contacts;
- said resistor comprising a composite material having a positive temperature coefficient of resistance whereby said resistor exhibits a first resistance at a first temperature and a second higher resistance at a second higher temperature, said material also having voltage dependent properties whereby said resistor exhibits a third resistance at a first voltage drop across said resistor and a fourth lower resistance at a second higher voltage drop across said resistor.
Dependencies are inferred from the claim text.