Patent Application
20090256658
The disclosed embodiments relate to circuit breaker current paths for providing additional current capability.
Circuit breakers are generally implemented to protect equipment from overcurrent situations, for example, when a short circuit or ground fault occurs in an electrical supply conductor. Upon the occurrence of an overcurrent condition, electrical contacts within the circuit breaker will generally open, stopping the supply of electrical current to the equipment. Designs for circuit breakers generally include accommodations for both high quiescent currents and high withstand currents. To maintain a high withstand current rating, the contacts must be locked closed at the current withstand rating and be able to withstand the large electrodynamic repulsion forces generated by the current flow.
Multipole circuit breakers include a variety of construction implementations such as blow open and non-blow open contact arms, overcentering and non-overcentering contact arms, single contact pair arrangements with the contact pair at one end of a contact arm and a pivot at the other end thereof, double contact pair arrangements, sometimes referred to as rotary breakers, with a contact pair at each end of a contact arm and a contact arm pivot intermediate or centrally located between the two ends, and single housing constructions with the circuit breaker components housed within a single case and cover. Other implementations include cassette type constructions with the current carrying components of each phase housed within a phase cassette and each phase cassette housed within a case and cover that also houses an operating mechanism.
Multipole circuit breakers are generally available in two, three, and four pole arrangements, with the two and three pole arrangements generally used in two and three phase circuits, respectively. Four pole arrangements are typically employed on three phase circuits having switching neutrals, where the fourth pole operates to open and close the neutral circuit in a coordinated arrangement with the opening and closing of the primary circuit phases.
Generally, each pole in a multiphase circuit breaker system is provided with a current sensing element that generates a trip signal which is used to trip the circuit breaker. Each pole may carry a significant amount of current.
The one or more finger assemblies 145 may operate to provide a mounting point for the one or more first arcing contacts 120 and one or more first main contacts and to provide a conduction path between the arcing and main contacts and a movable assembly load terminal 150. The one or more finger assemblies 145 may be resilient to allow the finger assemblies to pivot about a pivot point 115. The one or more finger assemblies 145 may also provide a spring force to assist in opening the circuit breaker contacts with a desired velocity upon an overcurrent occurrence.
The fixed contact assembly 105 may include one or more second arcing contacts 130 and one or more second main contacts 135. The fixed contact assembly 105 may also include a fixed assembly load terminal 155 on which the one or more second arcing contacts 130 and one or more second main contacts 135 may be mounted. The fixed and movable contact assemblies 105, 110 are generally constructed to withstand closing on a fault and thus have a significant current carrying capability.
It would be advantageous to provide a circuit breaker system with an increased current carrying capability.
The following are non limiting exemplary embodiments.
In one embodiment, an apparatus includes an enclosure, a plurality of circuit breaker sub poles, each enclosed within a chamber of the enclosure, and a plurality of arc chutes, each installed on one of the chambers enclosing the circuit breaker sub poles.
In at least one other embodiment, a method includes providing a plurality of circuit breaker sub poles, each enclosed within a chamber of an enclosure, and installing an arc chute on each of the enclosures.
The foregoing aspects and other features of the presently disclosed embodiments are explained in the following description, taken in connection with the accompanying drawings, wherein:
The disclosed embodiments are generally directed to a circuit breaker system with an increased current carrying capability. Other embodiments may include a modular arrangement of sub poles for each pole and individual arc chambers for each sub pole.
Circuit breaker 200 may include a fixed contact assembly 205 and a movable contact assembly 210 that pivots about a rotation point 250. The movable contact assembly 210 may generally include one or more first arcing contacts 220 and one or more first main contacts 225 (
Circuit breaker 200 may be configured as a single pole circuit breaker with a plurality of sub poles. In this exemplary embodiment, circuit breaker 200 includes two sub poles 240, 245.
It should be understood that circuit breaker 200 is not limited to two sub poles and may include one or any suitable number of sub poles. It should also be understood that each sub pole may include any number of fixed contacts and any number of movable contacts mounted on any number of finger assemblies.
In this embodiment, the sub poles 310 may have a common modular construction and may be interchangeable with each other. Each modular sub pole 310 may include a movable contact assembly 325 with one or more first arcing contacts 330 and one or more first main contacts 335. Each modular sub pole 310 may also include a fixed contact assembly 340 with one or more second arcing contacts 345 and one or more second main contacts 350.
Turning now to
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In some embodiments, enclosure 605 chambers may be substantially identical. Each chamber may have substantially the same volume within functional limits and may enclose an identically constructed sub pole. In alternate embodiments, each chamber may not be identical and may vary in volume. Also, in some embodiments, the enclosures may house at least one sub pole with a different number of finger assemblies.
In this embodiment, when the enclosure is assembled the sub poles may be connected to and closed by a common closing shaft 610. Cluster plates (not shown) may bridge one or more sub pole circuit breakers 625.
It should be understood that the foregoing description is only illustrative of the present embodiments. Various alternatives and modifications can be devised by those skilled in the art without departing from the embodiments disclosed herein. Accordingly, the embodiments are intended to embrace all such alternatives, modifications and variances which fall within the scope of the appended claims.
