Electricity: magnetically operated switches – magnets – and electr – Electromagnetically actuated switches – Tripping means
Reexamination Certificate
2001-08-17
2003-01-14
Donovan, Lincoln (Department: 2832)
Electricity: magnetically operated switches, magnets, and electr
Electromagnetically actuated switches
Tripping means
C335S016000, C335S035000, C218S022000
Reexamination Certificate
active
06507256
ABSTRACT:
BACKGROUND OF THE INVENTION
Circuit breakers are used to protect equipment from overcurrent situations caused, for example, by short circuits or ground faults in or near such equipment. In the event an overcurrent condition occurs, electrical contacts within the circuit breaker will open, stopping the flow of electrical current through the circuit breaker to the equipment. Circuit breakers may be designed for high quiescent currents and high withstand currents. To maintain a high withstand current rating, the contacts must be clamped closed at the current withstand rating. On the other hand, at the short circuit current level, the contacts must be capable of opening quickly. The drawback of having the contacts clamped close is that the contacts may not be able to open quickly at the short circuit current level.
SUMMARY OF THE INVENTION
The above discussed and other drawbacks and deficiencies of the prior art are overcome or alleviated by an auxiliary magnetic trip system and a method of tripping a circuit breaker. In an exemplary embodiment of the invention, the auxiliary magnetic trip system includes a strap configured to conduct a first level of electrical current and a second level of electrical current; a first u-shape collar with a first pole face, the first u-shape collar disposed around the strap; a trip lever rotatably mounted on an axis; and a holdback system releasably coupled to the trip lever, wherein the holdback system prevents movement of the trip lever at the first level of electrical current and releases the trip lever at the second level of electrical current. A method of tripping a circuit breaker includes flowing a first level of electrical current through a strap; inducing a magnetic force proportional to said first level of electrical current between a first pole face and a trip lever; preventing movement of said trip lever at said first level of electrical current; and releasing said trip lever at a second level of electrical current. The auxiliary magnetic trip system may be employed in a circuit breaker, such as for example a molded case circuit breaker, a rotary two-contact circuit breaker, an air circuit breaker, a residential circuit breaker, an industrial circuit breaker, a commercial circuit breaker, a miniature circuit breaker, a power circuit breaker, an insulated case circuit breaker, or any other circuit breaking device that has a withstand current rating and a short circuit current rating.
REFERENCES:
patent: 4764650 (1988-08-01), Bur et al.
patent: 4951015 (1990-08-01), Shea et al.
patent: 5731560 (1998-03-01), Nebon et al.
patent: 6018284 (2000-01-01), Rival et al.
patent: 6054912 (2000-04-01), Kanacko et al.
Arnold David
Castonguay Roger N.
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