Abstract:
Embodiments of an angled electrical contactor are provided. An aspect includes a moving contact bar including at least 4 contact discs, wherein a first contact disc and a second contact disc of the moving contact bar are located in a first plane, and a third contact disc and a fourth contact disc of the moving contact bar are located in a second plane, wherein the first plane and the second plane are distinct and are at an angle to each other. Another aspect includes a first stationary contact bar including at least 2 contact discs, wherein a first contact disc of first stationary contact bar is in a third plane, the third plane being substantially parallel to the first plane, and a second contact disc of the first stationary contact bar is in a fourth plane, the fourth plane being substantially parallel to the second plane.

Description:
BACKGROUND 
       [0001]    This disclosure relates generally to electrical contactors, and more specifically to an angled electrical contactor. 
         [0002]    Low current electrical contactors may be found in various electrical systems, for example, motor starters. In a prior art low-current electrical contactor  100 , an example of which is shown in  FIG. 1 , a moving contact bar  101  is positioned above a left stationary contact bar  102  and a right stationary contact bar  103 . The three contact bars  101 ,  102 , and  103  comprise respective contact discs  105 A-B,  104 A, and  104 B. The contact discs are attached to the contact bars, and positioned so that the contact discs on the stationary contact bars  102  and  103  are directly opposed to corresponding contact discs on the moving contact bar  101 . When the moving contact bar  101  is moved down toward the stationary contact bars  102  and  103 , contact disc  105 A approaches and touches contact disc  104 A, and contact disc  105 B approaches and touches contact disc  104 B, closing a circuit between stationary contact bars  102  and  103  so that a current enters stationary contact bar  102  from current input  108  and flows through moving contact bar  101  to stationary contact bar  103 , and exits stationary contact bar  103  via current output  109 . The moving contact bar  101  is mechanically driven upwards and downwards by an actuating device  107 , which transmits motion to the moving contact bar  101  through a spring  106 . 
         [0003]    As the moving contact bar  101  is mechanically driven toward the stationary contact bars  102  and  103 , one pair of contact discs (e.g.,  104 A and  105 A) may touch before the other pair (e.g.,  104 B and  105 B), due to manufacturing tolerances. Therefore the linkage between the actuating device  107  and the moving contact bar  101  must have some flexibility, so that the contact bar  101  can pivot to cause the second pair of contact discs (e.g.,  104 B and  105 B) to touch. The spring  106  may provide part of this flexibility. 
         [0004]    The current is constricted as it flows through the points where the contact disc pairs  104 A/ 105 A and  104 B/ 105 B touch each other. This constriction generates a magnetic force proportional to the square of the current, which acts to drive the contact discs pairs  104 A/ 105 A and  104 B/ 105 B apart. This force may be referred to as the blow-apart force. During a fault event in electrical contactor  100 , which may be caused by, for example, an external short circuit in the electrical system that contains electrical contactor  100 , the currents in electrical contactor  100  may exceed a rated current level of the electrical contactor  100 . The current is highly concentrated at each point of contact between the contact disc pairs, which may generate a correspondingly large blow-apart force at the point of contact. The spring  106  and the actuating device  107  must provide a closing force substantially greater than the total blow-apart force during a worst-case fault event. Otherwise, high currents may cause the metal that comprises the contact discs to melt at the point of contact, welding the contacts discs together. 
       SUMMARY 
       [0005]    Embodiments of an angled electrical contactor are provided. An aspect includes a moving contact bar, the moving contact bar comprising at least 4 contact discs, wherein a first contact disc and a second contact disc of the moving contact bar are located in a first plane, and a third contact disc and a fourth contact disc of the moving contact bar are located in a second plane, wherein the first plane and the second plane are distinct and are at an angle to each other. Another aspect includes a first stationary contact bar, the first stationary contact bar comprising at least 2 contact discs, wherein a first contact disc of first stationary contact bar is in a third plane, the third plane being substantially parallel to the first plane, and a second contact disc of the first stationary contact bar is in a fourth plane, the fourth plane being substantially parallel to the second plane. 
         [0006]    Embodiments of a method of operating angled electrical contactor are provided. An aspect includes moving a moving contact bar towards a first stationary contact bar, the moving contact bar comprising at least 4 contact discs, wherein a first contact disc and a second contact disc of the moving contact bar are located in a first plane, and a third contact disc and a fourth contact disc of the moving contact bar are located in a second plane, wherein the first plane and the second plane are distinct and are at an angle to each other. Another aspect includes the first stationary contact bar comprising at least 2 contact discs, wherein a first contact disc of first stationary contact bar is in a third plane, the third plane being substantially parallel to the first plane, and a second contact disc of the first stationary contact bar is in a fourth plane, the fourth plane being substantially parallel to the second plane. Another aspect includes based on the moving of the moving contact bar towards the first stationary contact bar, contacting the first contact disc of the moving contact bar to the first contact disc of the first stationary contact bar, and contacting the third contact disc of the moving contact bar to the second contact disc of the first stationary contact bar. 
         [0007]    Additional features are realized through the techniques of the present exemplary embodiment. Other embodiments are described in detail herein and are considered a part of what is claimed. For a better understanding of the features of the exemplary embodiment, refer to the description and to the drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
         [0008]    Referring now to the drawings wherein like elements are numbered alike in the several FIGURES: 
           [0009]      FIG. 1  illustrates an embodiment of a prior art electrical contactor. 
           [0010]      FIG. 2A  illustrates an embodiment of an angled electrical contactor. 
           [0011]      FIG. 2B  illustrates a side view of the angled electrical contactor of  FIG. 2A . 
           [0012]      FIG. 3  illustrates an embodiment of a single-pole double-throw contactor comprising an angled electrical contactor. 
           [0013]      FIG. 4  illustrates another embodiment of an angled electrical contactor. 
           [0014]      FIG. 5  illustrates an embodiment of a single-pole double-throw contactor comprising an angled electrical contactor. 
       
    
    
     DETAILED DESCRIPTION 
       [0015]    Embodiments of an angled electrical contactor are provided, with exemplary embodiments being discussed below in detail. Electrical contactors that are rated for use in high current applications (for example, above about 500 amperes) may provide more than one parallel path for the current. Dividing the current among two or more parallel paths reduces the blow-apart force, and also reduces the likelihood of a welding event during a fault. Because each path carries only half of the current during a fault event, the blow-apart force per path where the contact discs touch is reduced by a factor of four, and the closing force required from the actuating device and the spring is reduced by a factor of two. For an electrical contactor that includes two parallel paths, the moving contact bar may be made wider to accommodate two contact discs at each end; the stationary contact bar(s) are also made wider to include contact discs corresponding to the contact discs on the moving contact bar. However, achieving good, substantially simultaneous contact between four separate pairs of contact discs in an electrical contactor that comprise flat moving and stationary contact bars may be difficult due to manufacturing tolerances; for example, when three of the contact disc pairs are in contact, it may not be possible to maneuver the moving contact bar so that the fourth contact disc pair comes into contact. Therefore, the moving contact bar may be configured such that the contact discs at each end are at an angle to one another, with the contact discs on the stationary contact bars configured at a corresponding angle. In such an angled configuration, when three of the contact disc pairs are in contact with one another, it is still possible to maneuver the moving contact bar so that the fourth contact disc pair comes into contact. 
         [0016]      FIG. 2A  shows an embodiment of an angled electrical contactor  200 . The angled electrical contactor  200  comprises a moving contact bar  201  that is moved towards and away from stationary contact bars  102  and  103  by an actuating device  207  and a spring  206 . The angled electrical contactor  200  provides two parallel current paths; the first through contact disc pairs  205 A/ 204 A and  205 C/ 204 C, and the second through contact discs pairs  205 B/ 204 B and  205 D/ 204 D. The four contact discs  205 A-D on the moving contact bar  201  are not all in the same plane; rather, contact discs  205 A and  205 C are in a first plane, and contact discs  205 B and  205 D are in a second plane that is at an angle to the first plane. The two stationary contact bars  202  and  203  also have their respective contact discs  204 A-D arranged in two planes that are at an angle to each other corresponding to the angle between the first and second planes on the moving contact bar  201 ; e.g., contact disc  204 A and contact disc  204 C are in a third plane that is substantially parallel to the first plane, and contact disc  204 B and contact disc  204 D are in a fourth plane that is substantially parallel to the second plane. The actuating device  207  moves the moving contact bar  201  via spring  206  upwards to put the angled electrical contactor  200  in the off position, and downwards to put the angled electrical contactor  200  in the on position. When the angled electrical contactor  200  is in the on position, current is input to the angled electrical contactor  200  via stationary contact bar  202  via current input  208 , flows through from stationary contact bar  202  to moving contact bar  201  via contact discs  204 A-B and  205 A-B, from moving contact bar  201  to stationary contact bar  203  via contact discs  204 C-D and  205 C-D, and out of stationary contact bar  203  via current output  209 . Angled electrical contactor  200  allows the moving contact bar  201  to move in four degrees of freedom (vertical, roll, pitch, and yaw), to achieve good contact between the contact discs  205 A-D on moving contact bar  201  and contact discs  204 A-D on stationary contact bars  202  and  203 . Even if manufacturing tolerances prevent all four disc pairs from touching on the initial descent, there are three degrees of freedom remaining for moving contact bar  201  to move to allow all remaining disc pairs to touch. The moving contact bar  201  may have some flexibility, so that the contact bar  201  can pivot to utilize roll, pitch, and yaw movement. In some embodiments, a plurality of springs may be included in an angled electrical contactor instead of the single spring  206  shown in  FIG. 2 . 
         [0017]    The actuating device  207  provides the holding force between the moving contact bar  201  and stationary contact bars  202  and  203  when the angled electrical contactor is in the on position (i.e., is conducting current), and may be any appropriate actuating mechanism, for example, an electric solenoid, a manually operated lever, a cam and roller, or a pneumatic cylinder, in various embodiments. The actuating device  207  may travel a fixed distance, somewhat greater than the separation between the moving contact bar  201  and the stationary contact bars  202  and  203 . The excess travel acts to compress the spring  206 , which is dimensioned to provide a holding force on the moving contact bar  201 . Each of the four contact discs  205 A-D is therefore pressed against the opposing contact discs  204 A-D with more than one-fourth of the holding force from the spring  206 . As will be described below, the total force between the opposing contact discs is greater than the holding force. The contact bars  201 - 203  may be made from a metal with a relatively low electrical resistance, such as copper, in some embodiments. The contact discs  204 A-D and  205 A-D may be made from a metal that resists tarnishing, such as silver or cadmium, in some embodiments. In other embodiments, the contact discs  204 A-D and  205 A-D may be made from a metal with a relatively high melting point, such as tungsten. 
         [0018]      FIG. 2B  shows a side view of the angled electrical contactor  200  that shows the points where the contact discs  204 A and  205 A on moving contact bar  201 , and contact discs  204 B and  205 B on stationary contact bar  202 , contact each other when the angled electrical contactor  200  is conducting current. The contact discs  204 A-B and  205 A-B as shown in  FIG. 2  have a slightly domed or convex surface, which causes the contact point to be near the center of the discs. Angle  210  is the angle between the plane surface containing contact disc  205 A and the place surface containing contact disc  205 B on the moving contact bar  201 . Angle  210  is shown as 90° degrees in  FIG. 4B , but in various embodiments, angle  210  may be any angle that is greater than 0° but less than 180°. In some embodiments, angle  210  is between about 60° and 120°. On stationary contact bar  202 , contact disc  204 A is in a plane that is at an angle  211  with respect to the plane containing contact disc  204 B. Angle  211  corresponds to angle  210  and is approximately equal to 360° minus angle  210 . In an embodiment in which angle  210  is about 90°, the moving contact bar  201  must travel about 41% farther, as compared to an embodiment comprising flat moving and stationary contact bars, to achieve the same contact gap when the angled electrical contactor  200  is in the off position. However, the total closing force between the contact discs  204 A-D and  205 A-D is 41% greater than the force from spring  206  in such an embodiment, due to the wedging effect. This increased closing force improves the ability of the angled electrical contactor  200  to avoid welding. In embodiments in which the angle  210  is more acute, the extra travel that is required and the extra force that is generated both increase. Further embodiments of angled electrical contactors that incorporate a moving contact bar that is angled similarly to moving contact bar  201  of  FIGS. 2A-B , and one or more stationary contact bars that are angled similarly to stationary contact bars  202 - 203 , are discussed below with respect to  FIGS. 3-5 . 
         [0019]      FIG. 3  illustrates an embodiment of a single-pole double-throw contactor  300  comprising an angled electrical contactor as shown in  FIGS. 2A-B . In single-pole double-throw contactor  300  there are four stationary contact bars,  302  and  303  below, and  312  and  313  above. The moving contact bar  301  has four separate plane surfaces, each plane surface comprising two respective contact discs of contact discs  305 A-H. A first plane containing contact discs  305 A-B is at an angle with respect to a second plane containing contact discs  305 G-H; a third plane containing contact discs  305 C-D is at approximately the same angle with respect to a fourth plane containing contact discs  305 E-F. The first and third planes are substantially parallel, as are the second and fourth planes. The four stationary contact bars  302 ,  303 ,  312 , and  313  each have two respective contact discs  304 A-B,  304 C-D, and  314 A-B, and  314 C-D; on each stationary contact bar  302 ,  303 ,  312 , and  313 , the contact discs are mounted on two different planes that are substantially parallel to the plane surfaces of the moving contact bar  301  that contact the particular stationary contact bar. When the actuating device  307  drives the moving contact bar  301  downwards via spring  306  towards stationary contact bars  302  and  303 , the moving contact bar  301  closes the circuit between stationary contact bars  302  and  303 , and current flows from current input  308  through stationary contact bars  302  and  303  via moving contact bar  301 , through contacts discs  304 A-D and contact discs  305 C-F, to current output  309 . When the actuating device  307  drives the moving contact bar  301  upwards via spring  306  towards stationary contact bars  312  and  313 , the moving contact bar  301  closes the circuit between stationary contact bars  312  and  313 , and current flows from current input  310  through stationary contact bars  312  and  313  via moving contact bar  301 , through contacts discs  314 A-D and contact discs  305 A-B and  305 G-H, to current output  311 . In embodiments of a single-pole double-throw contactor  300 , the actuating device  307  is configured to be capable of generating the same amount force in both the downwards and upwards directions. 
         [0020]      FIG. 4  shows another embodiment of an angled electrical contactor  400 . The angled electrical contactor  400  comprises a moving contact bar  401  moved upwards and downwards by actuating device  407  and spring  406 . The angled electrical contactor  400  provides four parallel current paths; the first through contact disc pair  404 A/ 405 A, the second through contact disc pair  404 B/ 405 B, the third through contact disc pair  404 C/ 405 C, and the fourth through contact disc pair  404 D/ 405 D. The four contact discs  405 A-D on the moving contact bar  401  are not all in the same plane; rather, contact discs  405 A and  405 C are in a first plane, and contact discs  405 B and  405 D are in a second plane that is at an angle to the first plane. The stationary contact bar  402  also has contact discs  404 A-D arranged in two planes that are at an angle to each other that corresponds to the angle of the contacts discs  405 A-D on the moving contact bar  401 . The actuating device  407  moves the moving contact bar  401  upwards via the spring  406  to put the angled electrical contactor  400  in the off position, and downwards to put the angled electrical contactor  400  in the on position. Flexible conductor  410  inputs current to the angled electrical contactor  400 . When the angled electrical contactor  400  is in the on position, current is input to the angled electrical contactor  400  via moving contact bar  401  via current input  409  and flexible conductor  410 , flows through moving contact bar  401  to the stationary contact bar  402  via contact discs  404 A-D and  405 A-D, and out current output  408 .  FIG. 4  is shown for illustrative purposes only; in some embodiments, current may be input to the stationary contact bar, and output by the moving contact bar. 
         [0021]      FIG. 5  illustrates an embodiment of a single-pole double-throw contactor  500  comprising an angled electrical contactor as shown in  FIG. 4 . In single-pole double-throw contactor  500  there are two stationary contact bars,  502  below, and  503  above. The moving contact bar  501  has four separate plane surfaces, each plane surface comprising two respective contact discs of contact discs  505 A-H. A first plane containing contact discs  505 A-B is at an angle with respect to a second plane containing contact discs  505 G-H; a third plane containing contact discs  505 C-D is at approximately the same angle with respect to a fourth plane containing contact discs  505 E-F. The two stationary contact bars  502  and  503  each have four respective contact discs  504 A-D and  514 A-D on each stationary contact bar, the contact discs are mounted on two planes are at an angle that corresponds to the above-listed planes on moving contact bar  501 . Moving contact bar  501  is moved upwards and downwards via spring  506  and an actuating device such as actuating device  307  that was shown in  FIG. 3 . Flexible conductor  511  supplies current to the single-pole double-throw contactor  500 . When the actuating device drives the moving contact bar  501  downwards via spring  506 , the moving contact bar  501  comes into contact with stationary contact bar  502 , and current flows from current input  508  and flexible conductor  511  through moving contact bar  501 , through contacts discs  505 C-F and contact discs  504 A-D to stationary contact bar  502 , and out at current output  509 . When the actuating device moves the moving contact bar  501  upwards via spring  506 , the moving contact bar  501  comes into contact with stationary contact bar  503 , and current flows from current input  508  and flexible conductor  511  through moving contact bar  501 , through contact discs  505 A-B and  505 G-H to contacts discs  514 A-D to stationary contact bar  503 , and out at current output  510 .  FIG. 5  is shown for illustrative purposes only; in some embodiments, current may be input to the stationary contact bars, and output from the moving contact bar via the flexible conductor. 
         [0022]    The technical effects and benefits of exemplary embodiments include provision of parallel current paths and good, substantially simultaneous electrical contact in an electrical contactor. In some embodiments, the total closing force on all pairs of contact discs exceeds the force applied by the actuating device and the spring. 
         [0023]    The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the singular forms “a”, “an”, and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises” and/or “comprising,” when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. 
         [0024]    The corresponding structures, materials, acts, and equivalents of all means or step plus function elements in the claims below are intended to include any structure, material, or act for performing the function in combination with other claimed elements as specifically claimed. The description of the present invention has been presented for purposes of illustration and description, but is not intended to be exhaustive or limited to the invention in the form disclosed. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the invention. The embodiment was chosen and described in order to best explain the principles of the invention and the practical application, and to enable others of ordinary skill in the art to understand the invention for various embodiments with various modifications as are suited to the particular use contemplated.