Abstract:
A trip unit having a current carrying element, an anchor having an up and a down position, and an oscillator having a first position and a second position. The oscillator in the first position permits the anchor to move into the down position, and the oscillator in the second position blocks the anchor from moving into the down position. Additionally, a magnetic yoke surrounds the current carrying element and the anchor. A magnetic flux flowing through the magnetic yoke moves the anchor into the down position. A magnetic yoke surrounding the current carrying element and the oscillator provides a magnetic flux flowing through the magnetic yoke moves the oscillator into the first position, or into the second position.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of application Ser. No. 11/642,172 U.S. Pat. No. 7,515,025, which was filed Dec. 20, 2006 and issued Apr. 7, 2009, the entire contents of all of which are incorporated herein by reference. 
    
    
     BACKGROUND 
     1. Field of the Invention 
     The present disclosure relates generally to circuit breakers and, more particularly, the present disclosure relates to a current trip unit for a circuit breaker. 
     2. Description of the Related Art 
     Direct current fast switches serve to supervise the electrical current influx by a leader and to actuate a switch if a current threshold value is exceeded, for example, in a short circuit current. Typically, a warning is issued or the circuit is interrupted. 
     Conventional over-current breakers or tripping units have a magnetic yoke that surrounds a current-carrying leader. The magnetic yoke has anchors that are movable along an axis and the anchors are prevented from moving downward by a spring on the axis in a resting position. A magnetic flow through the magnetic yoke affects the anchor and forces the anchor against the resistance of the spring. If the current flowing through the leader exceeds a certain value, the magnetic force acting on the anchor is greater than the spring power of the spring. Thus, the anchor is pulled downward toward the magnetic yoke and correspondingly a trigger can be actuated to interrupt the circuit. 
     Conventional tripping units are bi-directional, which means that conventional units are not current direction sensitive. This conventional style of tripping is suitable in line feeder breakers. But in direct current systems there is also need to have a rectifier breaker, to protect a rectifier. A bi-directional tripping unit can not be used in a rectifier breaker to protect a rectifier. A rectifier is a current component of a circuit that allows current to pass in one direction yet blocks the flow of current in the other direction. It can be considered as a source of direct current. In fault conditions of a rectifier, a reverse current can appear in direction opposite to normal output of a rectifier. A rectifier breaker is a current component of a circuit that protects the rectifier in case of said fault of rectifier. For this reason, a conventional bi-directional unit cannot be used in a rectifier breaker, and a separate reverse current tripping device must be used with the bi-directional trip unit. 
     Accordingly, there is a need for a trip unit for a circuit breaker, which has the capacity to still provide circuit protection and function as a rectifier. 
     SUMMARY 
     The present disclosure provides a trip unit having a current leading element, an anchor having an up and a down position, and an oscillator having a first position and a second position. The oscillator in the first position permits the anchor to move into the down position, and the oscillator in the second position blocks the anchor from moving into the down position. Additionally, a magnetic yoke surrounds the current leading element and the anchor. A magnetic flux flowing through the magnetic yoke moves the anchor into the down position. A magnetic yoke surrounding the current leading element and the oscillator provides a magnetic flux flowing through the magnetic yoke moves the oscillator into the first position, or into the second position. 
     The present disclosure further provides trip unit having a movable anchor having a tripped position and an untripped position. An oscillator having a first and second position prevents movement of the anchor into the tripped position when the oscillator is in the second position, and allows the anchor to move into the tripped position when the oscillator is in the first position. A magnetic yoke surrounds the movable anchor and the oscillator and the magnetic yoke provides a magnetic current to move the movable anchor into the tripped position, and the magnetic yoke provides a magnetic current to move the oscillator into the first and second positions. 
     The above-described and other features and advantages of the present disclosure will be appreciated and understood by those skilled in the art from the following detailed description, drawings, and appended claims. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       These and other objects of the present disclosure will be more apparent from the following detailed description of the present disclosure, in conjunction with the accompanying drawings wherein: 
         FIG. 1  is a perspective view of an exemplary embodiment of the trip unit of the present disclosure; 
         FIG. 2  is a perspective view of a partial cross section of the trip unit of  FIG. 1 ; 
         FIG. 3  is a cross-sectional view, taken along line  2 - 2 , of the trip unit of  FIG. 1  with no current; 
         FIG. 4  is a cross-sectional view, taken generally along line  2 - 2 , of the trip unit of  FIG. 1  with forward flowing current; and 
         FIG. 5  is a sectional view, taken generally along line  2 - 2 , of the trip unit of  FIG. 1  with reverse flowing current. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring now to the figures and in particular to  FIGS. 1-5 , an exemplary embodiment of a current trip unit for a circuit breaker according to the present disclosure is shown and is generally referred to by reference numeral  10 . Current flowing through trip unit  10  is typically direct current. Trip unit  10 , advantageously, includes a blockade latch  20  that can rotate to prevent trip unit  10  from tripping when current is flowing through current leading elements  12  and  14  in a predefined forward direction. Blockade latch  20  in trip unit  10  can rotate to permit tripping when current is flowing through current leading elements  12  and  14  in a predefined reverse direction, or when no current is flowing through current leading elements  12  and  14 . 
     Current leading elements  12 ,  14  are surrounded by two magnetic yokes  16 ,  18 . A single current leading element can be used, as well, or more than two current leading elements could be used. The flow of electrical current through current leading elements  12 ,  14  generates a magnetic flux or current that is directed through magnetic yokes  16 ,  18 . The stronger the current flowing through current leading elements  12 ,  14 , the stronger the magnetic flux flowing through magnetic yokes  16 ,  18 . 
     The magnetic flux flowing through magnetic yoke  16  alters the position of a blockade latch  20  as magnetic flux is directed through an oscillator housing  22  and oscillator  23  housed inside. In an exemplary embodiment, oscillator  23 , which emits a magnetic field, is rotated as magnetic flux flows through magnetic yoke  16  and oscillator  23 . 
     Rotation of oscillator  23  causes rotation of blockade latch  20 , as the two components are linked. Rotation of blockade latch  20  by oscillator  23  causes blockade latch  20  to pivot under a plate  24  into either a blocked or an unblocked position. Blockade latch  20  is in an unblocking position when blockade latch is under a recess  26 . Blockade latch  20  remains in the unblocking position by resistance from spring  27 , until sufficient magnetic flux acting on armature  23  causes it to shift positions. Blockade latch  20  is considered to be in a blocking position when blockade latch  20  is under a bumper  30 . 
     Referring now to  FIG. 2 , lead rod  32  is mounted within trip unit  10 . Lead rod  32  is a linear rod that is positioned perpendicular to plate  24  and attached to plate  24  with securing elements  34  and  36 , but any known attachment means can be used. Leading rod  32  is also attached to the base of trip unit  10  with any known attachment means. Therefore, lead rod  32  is mounted in the interior of trip unit  10 , attached proximate the top of trip unit  10  (proximate plate  24 ) and attached proximate the base of trip unit  10 . 
     Slidingly attached to lead rod  32  is a movable anchor  40 . Lead rod  32  is inserted through a bore proximate the center of anchor  40 , and anchor  40  slides up and down on the axis provided by lead rod  32  when it is acted upon by magnetic yoke  18 . Thus, anchor  40  is slidable upon the center axis created by lead rod  32 . 
     At the base of anchor  40  is a spring  42  that resists downward movement of anchor  40 . A certain force exerted by spring  42  must be overcome to enable anchor  40  to move downward. As electric current flows through current lead elements  12 ,  14  a magnetic flux is created that attracts anchor  40  downward against spring  42 . Attraction of anchor  40  downward by magnetic flux flowing through magnetic yoke  18  causes tripping of trip unit  10 . The strength of electric current flowing through current leading elements  12 ,  14  determines the strength of magnetic flux flowing through magnetic yoke  18  and the potential for tripping of trip unit  10 . Also, the ability of trip unit  10  to trip is dependent on the positioning of oscillator  23  and blocking latch  20 . 
     Bumper  30  is disposed on anchor  40 , and as previously described, bumper  30  is the element that contacts blockade latch  20  when blockade latch  20  is in the blocking position. Attempts by anchor  40  to move downward will be prevented by bumper  30  on anchor  40  interacting with blockade  20  in the blocking position, i.e., under bumper  30 . 
     Trip unit  10  can include a second symmetrically placed blockade latch  20 - 1  positioned on the other side of trip unit  10 , opposite blockade latch  20 . Including a second blockade latch  20 - 1  on the opposite side of blockade latch  20  enables the better blocking of anchor  40 . A second bumper (not shown), similar to bumper  30 , placed on the opposite side of bumper  30 , would enable blockade  20 - 1  to assist in blocking anchor  40  from moving downward. Blockade latch  20 - 1  would also be joined to oscillator  23  and would respond simultaneously with blockade  20  and oscillator  23  as they both rotate. 
     Magnetic yoke  16  can effect the positioning of blockade latch  20  and oscillator  23  within oscillator housing  22 . More specifically, magnetic flux generated from electrical current flowing through current leading elements  12 ,  14  affects the position of oscillator  23  and blockade latch  20 , i.e., electric current flowing through current leading elements  12 ,  14  generates a magnetic flux that changes the position of oscillator  23 . 
     Blockade latch  20  is joined to an oscillator  23 , which oscillates between a blocking and an unblocking position depending on the direction of magnetic flux flowing through magnetic yoke  16  and oscillator  23 . The direction and strength of electric current flowing through current leading elements  12 ,  14  determines the direction of magnetic flux flowing through magnetic yoke  16  and oscillator  23 . Oscillator  23  changes position from blocked to unblocked by rotating within oscillator housing  22  around an axis  23  as the magnet field generated by oscillator  23  is confronted by the magnetic flux flowing through magnetic yoke  16 . In response to the magnetic flux flowing through magnetic yoke  16 , which flows perpendicular a magnetic field emitted from oscillator  23 , oscillator  23  rotates slightly into either a blocking or an unblocking position depending on the direction of the magnetic flux flowing through magnetic yoke  16 . 
     Magnets  44  on the interior of oscillator  23  can be positioned on both ends of oscillator  23  in order to enable oscillator  23  to emit a magnetic field. In other embodiments a single magnetic can be positioned within oscillator  23 , or oscillator  23  can be magnetized. In some embodiments, magnets  44  are permanent or electromagnetic magnets. 
     Magnets  44  are acted upon by magnetic flux  48  flowing through magnetic yoke  16  and oscillator  23 . As magnetic flux  48  flows through oscillator  23 , magnetic flux  48  interacts with the magnetic current originating from magnets  44 , the direction of the magnetic flux flowing through magnetic yoke  16  will cause oscillator  23  to rotate into a blocking or unblocking position. The direction of the magnetic flux  48  flowing through oscillator  23  will determine the direction that oscillator  23  will rotate. If no current is flowing through current leading elements  12 ,  14 , then no magnetic flux is generated and oscillator  23  and blocking latch  20  will remain in the resting position shown in  FIG. 3 . 
     Oscillator  23  and blockade latch  20  are held in the resting position by spring  27 . One side of spring  27  is held within a notch on a side of blockade latch  20  and the other end of spring  27  is held in place on wall  28 . The potential energy of spring  27  prevents blockade latch  20  from moving into the blocking position without magnetic flux sufficient to overcome the potential energy of spring  27 . 
       FIGS. 3-5  are sectional views of trip unit  10  that show the different positions of oscillator  23  and blocking latch  20  as magnetic flux  48  flows through magnetic yoke  16 . As previously noted, blockade latch  20  is linked to oscillator  23  and rotation of oscillator  23  leads to the rotation of blockade latch  20 . Electric current flowing through current leading elements  12 ,  14  generates a magnetic flux  48  that flows through magnetic yoke  16  and causes rotation of oscillator  23 . 
     Oscillator  23  is shown having a generally oval shaped profile, but this exemplary embodiment is only one potential shape for oscillator  23 . Oscillator  23  can be other shapes that permit oscillator movement as a result of a magnetic force. For example, oscillator  23  could be round or have rounded ends to permit rotation. 
     In other embodiments, oscillator  23  can be a non-rounded shape, such as a rectangle. If oscillator  23  is a non-rounded shape the oscillator would be unable to rotate and oscillator  23  would need to function in an alternative method. Instead of rotating oscillator  23 , it could move linearly, sliding blockade latch  20  into and out of a blocking position. Oscillator  23  would slide blockade latch  20  into either a blocking position under bumper  30 , or an unblocking position under recess  26  as magnetic flux affected oscillator  23 . 
     In other embodiments, the axis and position of oscillator  23  and blockade latch  20  can be changed from the arrangement described in this disclosure and such changes would be considered within the spirit and scope of the disclosure. For example, oscillator  23  can rotate on an axis perpendicular to axis  23 . 
       FIG. 3  shows the position of bumper  30 , oscillator  23  and blockade latch  20  when trip unit  10  has no current flowing through current leading elements  12 ,  14 . In this state oscillator  23  and blockade latch  20  are in an unblocking position and anchor  40  and bumper  30  are free to move downward, i.e., trip unit  10  is ready to trip. Since current is not flowing through current leading members  12 ,  14 , no magnetic flux is generated and oscillator  23  does not rotate from its resting position. 
       FIG. 4  shows the position of bumper  30 , oscillator  23  and blockade latch  20  when trip unit  10  has forward current flowing through current leading elements  12 ,  14 . In this state oscillator  23  and blockade latch  20  are in a blocking position and anchor  40  and bumper  30  are blocked from moving downward, i.e., trip unit  10  is unable to trip. Thus, electric current flowing through trip unit  10  in a predefined forward direction will be unable to trip due to blockade latch  20  preventing anchor  40  from moving into the tripped position. This is due to magnetic flux  48  moving oscillator  23  and blockade  20  into a blocking position. Contact between bumper  30  and blockade  20  prevents anchor  40  from moving downward and tripping. 
       FIG. 5  shows the position of bumper  30 , oscillator  23  and blockade latch  20  when trip unit  10  has reverse current flowing through current leading elements  12 ,  14 . In this state oscillator  23  and blockade latch  20  are in an unblocking position and anchor  40  and bumper  30  have already moved downward, i.e., trip unit  10  is just tripped. Thus, electric current flowing through trip unit  10  in a predefined reverse direction does will be capable of tripping due to the position of blockade latch  20  under recess, which will enable anchor to move into the tripped position. This is due to magnetic flux  48  moving oscillator  23  and blockade  20  into an unblocking position. Blockade  20  is in a position under recess  26  and anchor  40  is free to move downward and trip. The capability of trip unit  10  to allow electric current to flow in one direction and to prevent electric current to flow in another direction enables trip unit  10  to function as trip unit of rectifier breaker, to protect a rectifier. 
     Trip unit  10  has been described as having magnetic yoke  16  to direct magnetic flux  48  to flow through oscillator  23  to change the position of blockade latch  20 , and magnetic yoke  18  to direct magnetic flux  49  (separate number required for flux in yoke  18 , e.g.  49 ) to flow through anchor  40  to cause tripping. In other embodiments, the task of magnetic yokes  16 ,  18  can be consolidated into a single magnetic yoke (not shown). A single magnetic yoke would function similarly to the dual yoke embodiment, changing the positioning of anchor  40 , and changing the positioning of oscillator  23  with magnetic flux. 
     The particular type, including materials, dimensions and shape, of the various components of trip unit  10  that are utilized can vary according to the particular needs of trip unit  10 . 
     It should also be noted that the terms “first”, “second”, “third”, “upper”, “lower”, and the like may be used herein to modify various elements. These modifiers do not imply a spatial, sequential, or hierarchical order to the modified elements unless specifically stated. 
     While the instant disclosure has been described with reference to one or more exemplary embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope thereof. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the disclosure without departing from the scope thereof. Therefore, it is intended that the disclosure not be limited to the particular embodiment(s) disclosed as the best mode contemplated for carrying out the elements of this disclosure, but that the disclosure will include all embodiments falling within the scope of the appended claims.