Current limiter assembly for a circuit breaker
First Claim
1. A current limiting assembly for a circuit breaker having a pair of serially connected main circuit breaker contacts operable to an open position in response to the movement of a trip bar in response to either an overheat or overcurrent condition, the improvement comprising:
- a pair of current limiting contacts,an electromagnet assembly including a low resistance winding connected to said main contacts and operable in response to a high fault current for opening said current limiting contacts, anda bimetal serially connected between said winding and one of said current limiting contacts for responding to an overheat condition to move said trip bar for opening said main contacts.
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Accused Products
Abstract
The following specification describes a bimetal in the limiter assembly of a circuit breaker to operate the trip crossbar for opening the main circuit breaker contacts. An arm is also provided on one blade of the current limiter contacts to also operate the trip crossbar for ensuring rapid opening of the main contacts of the circuit breaker in response to high fault currents. The bimetal is connected between the electromagnet winding and one of the current limiter contact blades in shunt with a path of selected resistance. The resistance is selected as desired by connecting pigtail conductors of desired size either in shunt with or to selected portions of the bimetal to control the current passing through the bimetal for controlling the heat of the bimetal in accordance with the rating of the breaker. A calibration assembly for the bimetal is carried by the electromagnetic assembly.
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Citations
19 Claims
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1. A current limiting assembly for a circuit breaker having a pair of serially connected main circuit breaker contacts operable to an open position in response to the movement of a trip bar in response to either an overheat or overcurrent condition, the improvement comprising:
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a pair of current limiting contacts, an electromagnet assembly including a low resistance winding connected to said main contacts and operable in response to a high fault current for opening said current limiting contacts, and a bimetal serially connected between said winding and one of said current limiting contacts for responding to an overheat condition to move said trip bar for opening said main contacts. - View Dependent Claims (19)
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2. A current limiting assembly for a circuit breaker having a pair of serially connected main circuit breaker contacts operable to an open position in response to the movement of a trip bar in response to either an overheat or overcurrent condition, the improvement comprising:
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a pair of current limiting contacts, an electromagnet assembly including a low resistance winding connected to said main contacts and operable in response to a high fault current for opening said current limiting contacts, a bimetal serially connected between said low resistance winding and one of said current limiting contacts for responding to an overheat condition to move said trip bar for opening said main contacts, and means serially connected between said low resistance winding and said one current limiting contact and in shunt with said bimetal with said means having a resistance selected to enable opening of said main circuit breaker contacts in response to an overheat condition. - View Dependent Claims (3)
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4. A current limiting assembly for a circuit breaker having a pair of serially connected main circuit breaker contacts operable to an open position in response to the movement of a trip bar in response to either an overheat or overcurrent condition, the improvement comprising:
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a pair of current limiting contacts, an electromagnet assembly including a low-resistance winding connected to said main contacts operable in response to a high-fault current for opening said current limiting contacts, a bimetal serially connected between said winding and one of said current limiting contacts for responding to an overheat condition to move said trip bar for opening said main contacts, and a resistor having a positive temperature coefficient of resistance connected in shunt with said current limiting contacts for passing said high fault current in response to the opening of said current limiting contacts. - View Dependent Claims (5)
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6. A current limiting assembly for a circuit breaker having a pair of serially connected main circuit breaker contacts operable to an open position in response to the movement of a trip bar in response to either an overheat or overcurrent condition, the improvement comprising:
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a pair of current limiting contacts, an electromagnet assembly including a low resistance winding connected to said main contacts and operable in response to a high fault current for opening said current limiting contacts, a bimetal serially connected between said winding and one of said current limiting contacts for responding to an overheat condition to move said trip bar for opening said main contacts, a blade supporting said one current limiting contact and moved in response to energization of said winding by said high fault current for opening said current limiting contact, and means moved with said blade for moving said trip bar to open said trip bar to open said main contacts. - View Dependent Claims (7, 8, 9)
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10. For use in a circuit breaker having a pair of serially connected main circuit breaker contacts operable to an open position in response to the movement of a trip bar and having a pair of current limiting contacts adapted to be opened in response to a high fault current passing through an electromagnetic winding connected to said main contacts the improvement comprising:
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means serially connecting said winding to said current limiting contacts to enable operation of said electromagnetic winding for opening said current limiting contacts in resonse to a high fault current, and a bimetal connected in shunt with said means and passing a selected proportion of the current passing through said current limiting contacts for responding to an overheat condition to move said trip bar for opening said main contacts. - View Dependent Claims (11, 12, 13, 14, 15)
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16. For use in a circuit breaker having a pair of serially connected main circuit breaker contacts operable to an open position in response to the movement of a trip bar movable in response to either an overheat or an overcurrent condition and including a pair of current limiting contacts adapted to be opened in response to a high fault current passing through an electromagnetic winding connected to said main contacts the improvement comprising:
means serially connecting said winding to said current limiting contacts and having a resistance selected to enable operation of said electromagnetic winding for opening said current limiting contacts in response to a selected high fault current, and means operable in response to the opening of said current limiting contacts for moving said trip bar to open said main contacts. - View Dependent Claims (17, 18)
Specification