Abstract:
An advanced circuit breaker system and method includes first and second terminals to electrically couple the advanced circuit breaker to an electrical circuit. A cam applies a first torque to a rotatable contact arm, having an arm contact electrically coupled to the first terminal, from a first position to a second position of the contact arm and a second torque to the contact arm from the second position to a third position. A bimetal blade, having a blade contact electrically coupled to the second terminal, changes shape when electrical current flowing through it exceeds a threshold for at least a predetermined amount of time. The arm contact maintains contact with the blade contact when the first torque occurs and separates from the blade contact when the second torque occurs. The blade contact changes shape to increase separation from the arm contact if electrical current exceeds at least a certain amount above the threshold.

Description:
TECHNICAL FIELD  
         [0001]    The invention relates generally to protection equipment for electrical circuits, and more particularly to electrical circuit breakers.  
         BACKGROUND OF THE INVENTION  
         [0002]    A circuit protector device, such as a fuse or circuit breaker, protects an electrical circuit from damage due to over-current and short-circuit conditions. An over-current condition occurs when there is too high a level of electrical current flowing in an electrical circuit due to power demand of circuit loads being greater than the design capacity of the electrical circuit. A short-circuit condition occurs when an electrically conductive member makes contact with two points of an electrical circuit causing electrical current to bypass the circuit&#39;s electrical load resulting in extremely high electrical currents. Over-current and short-circuit conditions can damage conductor wires of electrical circuits due to overheating of the conductor wires and result in burning of the wire insulation. Other damage caused by over-current and short-circuit conditions may result with the electrical or electronic equipment found in a particular electrical circuit. In a protected electrical circuit, when an over-current or short-circuit condition occurs, the circuit protector device acts as an open electrical switch thereby preventing additional electrical current from flowing in the protected electrical circuit.  
           [0003]    Fuses protect electrical circuits by using a “fusible link” that melts to cause an open circuit condition when the amount of electrical current flowing through the protected electrical circuit exceeds a known level. Circuit breakers use thermal or magnetic based mechanisms that are sensitive to the amount of electrical current flowing through a protected electrical circuit. These thermal and magnetic based mechanisms also cause an open switch condition when electrical current exceeds a known level. Circuit breakers become progressively more expensive, relative to fuses, for applications where the operational level of electrical current is very high. Generally, fuses are less expensive, however, circuit breakers are much more convenient than fuses since they can be reused whereas fuses must be replaced.  
           [0004]    Some challenging applications of circuit breakers involve environments having at least one of the following conditions: high temperature, high humidity, and inherent vibrational forces. The marine environment has these characteristics. Circuit breakers generally have many components that increase the cost of their manufacture. Further, these many components must perform reliably both as individual components and as a collective unit. Given the convenience of circuit breakers compared to fuses, there is much motivation for improving circuit breakers to further extend their scope of application and reduce their cost of manufacture while maintaining and increasing their reliability and performance characteristics.  
         SUMMARY OF THE INVENTION  
         [0005]    The present invention resides in a method and system for an advanced circuit breaker including a housing, first and second electrical terminals, a contact arm, a cam up, a torque generating member, and a bimetal blade. The first and second electrical terminals are affixed to the housing and are configured to electrically couple the electrical circuit breaker to the electrical circuit. The contact arm includes first and second portions. The first portion of the contact arm is electrically coupled to the first terminal and some aspects included being rotatably mounted within the housing. The second portion of the contact arm has an arm contact affixed and electrically coupled thereto.  
           [0006]    Some aspects included the cam having first and second portions wherein the first portion is rotatably mounted within the housing. In some aspects, the second portion is movably coupled to the contact arm such that rotation of the cam in a first rotational direction through a first amount of rotation causes rotation of the contact arm in a second rotational direction and further rotation of the cam in the first rotational direction through a second amount of rotation beyond the first amount of rotation causes rotation of the contact arm in a direction counter to the second rotational direction. In some aspects, the torque generating member is configured to apply a torque to the cam tending to rotate the cam in the first rotational direction.  
           [0007]    In some aspects, the bimetal blade is electrical coupled to the second electrical terminal and is configured to change shape based upon an amount of electrical current above a threshold level passing through the bimetal blade for at least a predetermined amount of time. The bimetal blade has a blade contact affixed and electrically coupled thereto. The bimetal blade is shaped and positioned with respect to the contact arm such that the blade contact contacts the arm contact to prevent the contact arm from rotating in the second rotational direction when the amount of electrical current flowing through the bimetal blade is below the threshold level. Further aspects included the bimetal blade being shaped and positioned with respect to the contact arm to allow the contact arm to rotate in the second rotational direction with the cam rotating in the first rotational direction through the first amount of rotation and to allow the contact arm to remain in contact with the blade contact when the amount of electrical current flowing through the bimetal blade increasingly exceeds the threshold level by up to a first amount of electrical current for at least at predetermined amount of time.  
           [0008]    Other aspects include the electrical circuit breaker further comprising a conductive shaft electrically coupled to the first terminal and wherein the first portion of the contact arm is electrically coupled to the first terminal through the conductive shaft. Alternative aspects include the electrical circuit breaker having a camshaft rotatably mounted within the housing and wherein the cam is fixedly attached to the camshaft.  
           [0009]    Other aspects include the bimetal blade being further shaped and positioned with respect to the contact arm such that when the amount of electrical current flowing through the bimetal blade exceeds the first amount, the blade changes shape and position with respect to the contact arm to cause the blade contact to stop contacting the arm contact and thereby allow the contact arm to rotate counter to the second rotational direction with the cam rotating in the first rotational direction through the second amount of rotation beyond the first amount of rotation.  
           [0010]    Other aspects include the electrical circuit breaker further comprising a breaker throw lever fixedly attached to the cam such that a torque applied to the breaker throw lever opposite and exceeding the torque applied to the cam will prevent the contact arm from rotating when the bimetal blade changes shape and position with respect to the contact arm as the electrical current through the bimetal blade exceeds the threshold level for at least a predetermined amount of time. Further aspects include the contact arm having first and second contact arm rails extending longitudinally away from the first portion of the contact arm and substantially parallel to one another. Each of the first and second contact arm rails having a contact arm slot extending longitudinally within and having a cam slidably retained thereto to movably connect the cam to the contact arm.  
           [0011]    Other aspects include the cam having first and second cam arms extending longitudinally away from the first portion of the cam and substantially parallel to one another. The first and second cam arms have a pin coupled thereto and extending therebetween and a roller so mounted on the pin to rollably engage the contact arm.  
           [0012]    Other aspects include the bimetal blade configured and positioned to change shape and position with respect to the contact arm based upon the amount of electrical current passing through the bimetal blade above the threshold level and independent from rotational position of the cam. Further aspects include the bimetal blade being a snap disc or having the shape of a Valverde blade. Further aspects include the contact arm being sized and positioned with respect to the bimetal blade such that the arm contact maintains substantial contact with a blade contact without electrical arcing occurring between the arm contact and the blade contact as the bimetal blade changes shape and position with respect to the contact arm and as the cam rotates through the first amount of rotation.  
           [0013]    Other aspects include the electrical circuit breaker having a conductive shaft electrically coupled to the first terminal and wherein the first portion of the contact arm is electrically and rotatably coupled to the conductive shaft. Further aspects include the electrical circuit breaker having an electrically conductive bearing lubricated with electrically conductive lubricant and configured to electrically and rotatably couple the first portion of the contact arm to the conductive shaft. Other aspects include the torque generating member being a spring shaped and positioned to apply a torque to the cam in the first rotational direction. Other aspects include the electrical circuit breaker having a camshaft having the cam rotatably mounted thereto and wherein the spring is coupled to the cam. Other aspects include a camshaft being coupled to the housing and wherein the cam is rotatably mounted on the camshaft.  
           [0014]    Other aspects include the breaker throw lever being fixedly attached to the camshaft such that the position of the breaker throw lever indicates whether the arm contact and the blade contact are in contact with one another. Other aspects include the housing having a housing cover which includes an opening with the camshaft projecting therethrough and beyond an exterior surface of the housing cover and configured for attachment of the breaker throw lever thereto and also having a seal positioned with respect to the camshaft, the breaker throw lever, and the opening of the housing cover to prevent fluids from entering into an internal containment area of the housing from areas adjacent to the external surface of the housing cover.  
           [0015]    Other aspects include a current sensitive structure electrically coupled to the second electrical terminal configured to change shape based upon amount of electrical current above the threshold level passing through the current sensitive structure for at least a predetermined amount of time. Other aspects include a linkage coupled to the contact arm configured to apply rotational torque to the contact arm tending to rotate the contact arm in a rotational direction from the first position with contact arm to the second position the contact arm.  
           [0016]    Other features and advantages of the invention will become apparent from the following detailed description, taken in conjunction with the accompanying drawings. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0017]    [0017]FIG. 1 is an isometric view of an advanced electrical breaker comprising one embodiment of the invention.  
         [0018]    [0018]FIG. 2 is an isometric view of the advanced circuit breaker of FIG. 1 with its housing cover removed.  
         [0019]    [0019]FIG. 3 is an exploded isometric view of the advanced circuit breaker of FIG. 1.  
         [0020]    [0020]FIGS. 4A and 4B are schematic diagrams of the advanced circuit breaker as shown in FIG. 2 with and without housing cover, respectively, in fully closed position.  
         [0021]    [0021]FIGS. 5A and 5B are schematic diagrams of the advanced circuit breaker as shown in FIG. 2 with and without housing cover, respectively, in mid-position.  
         [0022]    [0022]FIGS. 6A and 6B are schematic diagrams of the advanced circuit breaker as shown in FIG. 2 with and without housing cover, respectively, in fully open position.  
         [0023]    [0023]FIGS. 7A and 7B are schematic diagrams of the advanced circuit breaker as shown in FIG. 2 with and without housing cover, respectively, in fully open position of the contact arm and the fully closed position of the bimetal blade.  
         [0024]    [0024]FIGS. 8A and 8B are schematic diagrams of the advanced circuit breaker as shown in FIGS. 1 and 2, respectively, illustrating an inherent safety feature to protect against accidental premature resetting of the circuit breaker. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0025]    Embodiments of an advanced thermal based electrical circuit breaker system and method are described. As shown in the drawings for purposes of illustration, the present invention is embodied in an advanced circuit breaker  10  to serve as a circuit protection device for an electrical circuit. The advanced circuit breaker  10  has a breaker housing  12  and a housing cover  13  affixed to the breaker housing with rivets  14 . A cover gasket  15  is positioned between the breaker housing  12  and the housing cover  13  to prevent moisture from entering into the breaker housing. In some embodiments, the breaker housing is made of a thermoset polyester material, but other embodiments use other non-conductive materials known in the art.  
         [0026]    The advanced circuit breaker  10  further includes a breaker throw lever  16  to indicate status of the advanced circuit breaker and to be used as a switch lever to move components internal to the breaker housing  12  as further described below. The embodiment of the advanced circuit breaker  10  depicted in FIG. 1 is configured for mounting on a wall or other surface. Other embodiments are configured for mounting within panel type fixtures or are configured for other mounting arrangements. A mounting bracket  18  with bracket mounting holes  20  allows for wall-type mounting of the advanced circuit breaker  10 . A first electrical terminal  21  and a second electrical terminal  22 , each having electrical terminal compression washers  23  and an electrical terminal nut  24 , are used to electrically coupled the advanced circuit breaker  10  to a protected circuit (not shown).  
         [0027]    Components internal to the breaker housing  12  are shown in FIG. 2. The advanced circuit breaker  10  has a contact arm  26  rotatably coupled to an electrically conductive shaft  28  by a conductive bearing  30 . The conductive bearing  30  is lubricated with a conducting material such as a mixture of grease and finely powdered silver or other powdered electrically conducting material. Furthermore, the conductive shaft  28  is electrically coupled to the first electrical terminal  21 . Complications found with conventional circuit breakers regarding electrical coupling of contact arms with electrical terminals, such as involving so-called pigtail connections, are thus avoided. The contact arm  26  and the conductive bearing  30  are secured in position with means such as a conductive shaft C-clip  31 , aptly shaped walls of the breaker housing  12 , or other configurations. In other embodiments, the contact arm  26  is affixed to the conductive shaft  28  and the conductive shaft is electrically and rotatably coupled to the first electrical terminal  21 .  
         [0028]    The advanced circuit breaker  10  has a cam  32  fixedly coupled to a camshaft  34  and positioned to receive a biasing torque, indicated by Arrow “a”, from a biasing spring  36  or other torque generating member. When the advanced circuit breaker  10  is fully assembled, the breaker throw lever  16  is attached to the camshaft  34  allowing the breaker throw lever to indicate the status of the rotational position of the camshaft and also permitting manual rotational movement of the camshaft by movement of the breaker throw lever. The breaker throw lever  16  serves many purposes, which will be further elucidated by the discussion below. In short, the breaker throw lever  16  serves by indicating operational status of the advanced circuit breaker  10 , by acting as an electrical switch throw lever for the advanced circuit breaker during periods of normal operation without over-current or short-circuit conditions, and by acting as a reset lever to reset the advanced circuit breaker after being tripped by an over-current or short-circuit condition. As discussed further below, the contact arm  26  is coupled to the cam  32  such that the cam serves as a linkage whereby movement of the camshaft  34  causes movement of the contact arm  26 .  
         [0029]    A bimetal blade  38 , being a current sensitive structure, is electrically coupled to the second electrical terminal  22 . The bimetal blade  38  has two metal layers with differing thermal expansion properties such that the bimetal blade has a first configuration, typically being flat, when at temperatures below a threshold temperature and a second configuration, which progressively bends in a continuous fashion away from the first configuration as temperature of the bimetal blade rises farther above the threshold temperature and stays above the threshold temperature for at least a predetermined amount of time until typically the bimetal blade reaches a snapping position and snaps to change shape in a discontinuously buckling, snapping fashion to quickly move away from and clear of the contact arm. For instance, for an exemplary embodiment, for a current at above 135% of the amperage rating, the exemplary embodiment would trip after at least one hour and for a current rating above 200% of the amperage rating, the exemplary embodiment would trip after at least 2 minutes. According to conventional knowledge regarding circuit breakers, the bimetal blade  38  is fashioned with respect to a particular threshold temperature so chosen for particular amperage ratings based on amount of current and duration of time in which the amount of current occurs. The bimetal blade  38  is positioned adjacent to the contact arm  26  such that as the temperature of the bimetal blade rises farther above the threshold temperature and stays above the threshold temperature for at least a predetermined amount of time, the bimetal blade progressively bends in a continuous fashion farther away from the contact arm  26 , until the bimetal blade reaches the snapping position to subsequently snap. The advanced circuit breaker  10  can employ many varieties of bimetal snap blades or bimetal snap discs of appropriate dimensions and material, which will respond with progressive continuous bending and culminate in a discontinuously buckling, snapping motion away from the contact arm  26  as a result of heating due to a predetermined level of electrical current occurring for a given duration of time. Magnitude of current above a predetermined level governs the duration of time required for the bimetal blade  38  to snap resulting in tripping of the advanced circuit breaker  10 . This conveniently provides a mechanical analog of the thermal condition of the protected device, such as a motor or other electrical device. In the illustrated embodiment, a valverde shape is used for the bimetal blade  38 .  
         [0030]    An exploded view of the advanced circuit breaker  10  showing the components internal to the breaker housing  12  is provided in FIG. 3. As shown, the cam  32  is secured to the camshaft  34  for rotation therewith by a camshaft pin  40 , which prevents rotational movement of the cam with respect to the camshaft. C-clip washers  41  prevent the cam  32  from sliding longitudinally along the camshaft and prevent the cam from coming off the camshaft.  
         [0031]    The contact arm  26  further includes two elongated contact arm rails  27  each having a longitudinally extending rail slot  44 . Each contact arm rail  27  has an internal surface facing the internal surface of the other contact arm rail. Each of the contact arm rails also has an external surface that is opposite its internal surface. Extending longitudinally between the contact arm rails  27  and affixed thereto is a contact arm wall  29  with an elongated internal smooth walled surface facing toward the cam  32 .  
         [0032]    The cam  32  includes two cam rails or arms  33 , each having a cam arm hole  35 . The cam arms  33  have internal surfaces facing one another and each of the cam arms has an external surface that is opposite its internal surface.  
         [0033]    The cam arms  33  extend toward and terminate with the cam arm holes  35  positioned between the contact arm rails  27 . The distal ends of the cam arms  33  are movably retained by the contact arm  26  by a cam rivet or axle  42 , which extend through the rail slots  44  and the cam arm holes  35 . Cam rivet washers  45  are positioned on the cam axle  42  adjacent each of the external surfaces of the contact arm rails  27 . The cam  32  is positioned and sized relative to the contact arm  26  such that the external surface of each of the cam arms  33  is adjacent one of the internal surfaces of the contact arm rails  27 . A roller  46  having a center hole  47  is positioned between the cam arms  33  and rotatably mounted on the cam axle  42 . The cam axle  42  is slidably retained in the rail slots  44  with the roller  46  rotatably engaging the internal surface of the contact arm wall  29  to be movably retained by the contact arm  26   
         [0034]    The bimetal blade  38  includes a blade bracket  48  used to secure the bimetal blade  38  to the breaker housing  12  with a blade screw  50 , and includes a blade spacer  52  used to adjust the bimetal blade. The bimetal blade  38  further includes a blade contact  53  shaped and positioned on the bimetal blade to contact an arm contact  54  on the contact arm wall  29  of the contact arm  26  when the advanced circuit breaker  10  is in its fully closed position, thereby allowing current to flow in its associated protected electrical circuit.  
         [0035]    The breaker throw lever  16  is attached to the camshaft  34  by a throw lever screw  55 . A throw lever gasket  56  serves to seal the breaker throw lever  16  to prevent moisture from entering the breaker housing  12 . A throw lever screw cover  57  protects the throw lever screw  55 .  
         [0036]    The advanced circuit breaker  10  uses the biasing torque, indicated by the Arrow “a”, of the biasing spring  36 , to keep the blade contact  53  and the arm contact  54  either together in electrical contact or separated apart depending upon the rotational position of the cam  32 . In the fully closed position of the advanced circuit breaker  10 , as shown in FIGS. 4A and 4B, the biasing torque of the biasing spring  36  causes a force, indicated by Arrow “b”, to be applied by the cam arms  33  through the roller  46  to the contact arm  26 , thereby causing a force, indicated by Arrow “c”, to be applied by the arm contact  54  on the blade contact  53 . The bimetal blade  38  is pre-tensioned such that in the fully closed position of the advanced circuit breaker  10  the bimetal blade causes a force to be applied by the blade contact  53  on the arm contact  54  in a direction opposite to that indicated by the Arrow “c.” As long as the blade contact  53  remains stationary, the contact arm  26  will remain stationary and in turn, the cam  32  will remain locked in a stationary fully closed position. This locking action has potential in reducing false triggering found with conventional circuit breakers.  
         [0037]    When an over-current or short-circuit condition occurs, the bimetal blade  38  will begin to trip from the fully closed position of the advanced circuit breaker  10  to its fully open position by bending toward the direction indicated by Arrow “d” thereby allowing the camshaft  34  to rotate clockwise in the direction of the biasing torque indicated by Arrow “a”. As the camshaft  34  begins from the fully closed position of the advanced circuit breaker  10  to rotate in the direction of the biasing torque indicated by Arrow “a”, the roller  46  will continue to apply a force against the contact arm  26  resulting in a force continuing to be applied by the arm contact  54  against the blade contact  53 , generally in the direction indicated by the Arrow “c”. This continual force being applied by the arm contact  54  against the blade contact  53 , through an enhanced “wiping motion”, reduces or eliminates unwanted contact arcing, contact chatter, and contact creep found with tripping motion or gradually increased load current of a conventional circuit breaker. The continual force being applied by the arm contact  54  against the blade contact  53  serves to maintain contact forces between the arm contact and the blade contact during the gradual continuous bending motion of the bimetal blade  38  toward the fully open position and also for a certain extent of motion by the contact blade after it has snapped to change shape as explained further below.  
         [0038]    As the bimetal blade  38  continues to bend even further toward the direction indicated by the Arrow “d”, and after the bimetal blade has snapped to change shape, the cam  32  and the contact arm  26  will reach a mid-position, as shown in FIGS. 5A and 5B. When moving from the fully closed position, just before reaching this mid-position, the arm contact  54  will no longer exert a force in the direction indicated by Arrow “c” in FIG. 4A. Due to snapping of the bimetal blade  38 , the cam  32  and the contact arm  26  will then rapidly reach the mid-position whereby a force indicated by Arrow “e” is applied by the cam axle  42  on to the contact arm  26  causing a force to be applied on to the arm contact  54  in a direction generally indicated by Arrow “f” away from the blade contact  53 . Once the cam  32  and the contact arm  26  move into this mid-position, the camshaft  34  will continue to rotate rapidly in the clockwise direction of the Arrow “a” until the cam  32  and the contact arm  26  reach its fully open position, as shown in FIGS. 6A and 6B. In the fully open position, the blade contact  53  and the arm contact  54  are fully separated from each other due to the bending of the snapped bimetal blade  38  in the direction generally indicated by the Arrow “d” and also due to the biasing torque causing a force indicated by the Arrow “g” to be applied by the cam axle  42  on to the contact arm  26  resulting in a force on the arm contact  54  in the direction generally indicated by Arrow “h”.  
         [0039]    This movement of the cam  32  and the contact arm  26  from the mid-position to the fully open position occurs regardless of whether the bimetal blade  38  continues to be bent in its snapped condition and in the direction generally indicated by the Arrow “d”. Generally during over-current or short-circuit conditions of the associated electrical circuit protected by the advanced circuit breaker, the bimetal blade  38  will continue to be bent in its snapped condition in the direction generally indicated by the Arrow “d”. After an over-current or short-circuit condition has occurred and the bimetal blade  38  has cooled to return to its fully closed position, the contact arm  26  will remain in its fully open position, as shown in FIGS. 7A and 7B, until the advanced circuit breaker  10  is reset.  
         [0040]    In summary, two independent mechanical actions are involved in separation of the blade contact  53  from the arm contact  54 , which enhances reliability and performance of the advanced circuit breaker  10 . Bending forces causing a gradual continuous first motion and a rapid discontinuously buckling, snapping second motion of the bimetallic blade  38  causes movement of the blade contact  53  in the direction generally indicated by the Arrow “d” and the biasing torque indicated by the Arrow “a” causes movement of the arm contact  54  in the direction generally indicated by the Arrows “f” and “h”. With the advanced circuit breaker  10 , separation distance between the blade contact and the arm contact can potentially be increased relative to conventional circuit breakers contacts because both the blade contact and the arm contact of the advanced circuit breaker move in opposite directions when the advanced circuit breaker is tripped to the fully open position due to an over-current or short-circuit condition. This bi-directional movement of the blade contact  53  and the arm contact  54  may also help to potentially reduce the number of false triggers compared with conventional circuit breakers.  
         [0041]    The advanced circuit breaker  10  can also be used as a manual switch in which a clockwise torque is applied to the breaker throw lever  16  to open the advanced circuit breaker from the fully closed position to the fully open position. The advanced circuit breaker  10  can be manually switched to the fully open position, even when the bimetal blade  38  is cool enough to be in the position shown in FIG. 4A, if enough clockwise torque is applied to the breaker throw lever  16  to bend the bimetal blade in the direction indicated by the Arrow “d” as the breaker throw lever rotates from the fully closed position to the mid-position. Once the breaker throw lever  16  is moved just past the mid-position, the biasing torque indicated by the Arrow “a” will continue to move the breaker throw lever to the fully open position and since the bimetal blade  38  is cool, it will move back to its fully closed position.  
         [0042]    To reset the advanced circuit breaker  10 , counterclockwise torque is typically applied by hand to the breaker throw lever  16  to move the breaker throw lever from the fully open position to the fully closed position by overcoming the biasing torque indicated by the Arrow “a”. If the bimetal blade  38  has cooled down from an elevated temperature caused by an over-current or short-circuit condition, additional torque is typically applied by hand to the breaker throw lever to flex the bimetal blade in the direction generally indicated by the Arrow “d” to move the breaker throw lever  16  from the fully open position to just past the mid-position in the direction of the fully closed position. In moving the breaker throw lever  38  past the mid-position to the fully closed position, the cooled bimetal blade  38  will return to its unflexed position in the general direction opposite of the Arrow “d” so less torque will typically be needed to be applied to the breaker throw lever  16  to move the breaker throw lever past the mid-position to the fully closed position.  
         [0043]    If an attempt is made to reset the advanced circuit breaker  10  before an over-current or short-circuit condition has ended by applying a force “j” to the breaker throw lever  16 , as shown in FIGS. 8A and 8B, the cam  32  and the contact arm  26  will manually be returned to their fully closed position while the bimetal blade  38  cycles between its fully open and its fully closed positions as indicated by movement arrow “k”. During the cycling of the bimetal blade  38  between its fully open and its fully closed positions, the bimetal blade first cools down from an elevated temperature caused by an over-current or short-circuit condition to flatten out and go from its fully open position to its fully closed position. Brief contact will then occur between the blade contact  53  and the arm contact  54  causing an elevation in temperature of the bimetal blade due to the over-current or short-circuit condition and subsequent bending of the bimetal blade away from its fully closed position and return to its fully open position. The duration of time that the bimetal blade will remain in its fully closed position with contact of the blade and arm contacts  53  and  54  during this cycling behavior is inversely proportional to the level of excess current caused by the over-current or short-circuit condition occurring in the circuit. Thus, the advanced circuit breaker  10  has an inherent redundant safety feature that will continue to protect an electrical circuit even though an operator mistakenly tries to prematurely reset or otherwise close the advanced circuit breaker before termination of an over-current or short-circuit condition.  
         [0044]    For example, exemplary embodiments of the advanced circuit breaker  10  include those with maximum operational amperage ratings of between 100% and 135% of 25 to 150 amperes and interrupt ratings DC of 5,000 amperes. Other embodiments have other operation amperage ranges and interrupt ratings to protect electrical circuits having either direct or alternating current.  
         [0045]    From the foregoing it will be appreciated that, although specific embodiments of the invention have been described herein for purposes of illustration, various modifications may be made without deviating from the spirit and scope of the invention. Accordingly, the invention is not limited except as by the appended claims.