Abstract:
A component is for an electric power system. The component includes: a user access panel; a first element for directing visible light; a second element for directing visible light, the second end of the first element facing the second end of the second element; a movable conductor structured to move between a first position and a second position; and a stationary conductor structured to engage the movable conductor. In the first position the movable conductor is disposed between the second end of the first element and the second end of the second element, thereby blocking visible light from passing from the first element to the second element. In the second position the movable conductor is not disposed between the second end of the first element and the second end of the second element, thereby permitting visible light to pass from the first element to the second element.

Description:
BACKGROUND 
     1. Field 
     The disclosed concept pertains generally to components for electric power systems. The disclosed concept also pertains to methods of determining whether a power circuit in an electric power system is open or closed. 
     2. Background Information 
     Electric power systems incorporate switches for control and protection purposes. Distribution systems, which form part of an overall electric power system, include main and branch power buses and circuit breakers mounted in metal cabinets to form switchgear. Interruption of current flow in the buses of the distribution system by a circuit breaker creates an arc as the contacts of the circuit breaker open. These arcs caused by interruption are contained and extinguished in the normal course of operation of the circuit breaker. 
     At times, however, unintended arcing faults can occur within switchgear cabinets, such as between power buses, or between a power bus and a grounded metal component. Such arcing faults can produce high energy gases, which pose a threat to the structure and nearby personnel. This is especially true when maintenance is performed on or about live power circuits. Frequently, a worker inadvertently shorts out the power bus, thereby creating an arcing fault inside the enclosure. The resulting arc blast creates an extreme hazard and could cause injury or even death. This problem is exacerbated by the fact that the enclosure doors are typically open for maintenance. 
     There are disconnect switches intended to isolate portions of an electric power system for maintenance that do not allow for indication of open or closed power circuit status by a user in locations readily visible to a user. Because of this, accessing energized electrical equipment is more dangerous. 
     There is room for improvement in components for electric power systems. 
     There is also room for improvement in methods of determining whether a power circuit in an electric power system is open or closed in cases where the switch contacts are not directly visible by a user. 
     SUMMARY 
     These needs and others are met by embodiments of the disclosed concept in which visible light is directed through elements to determine the position of a movable conductor. 
     In accordance with one aspect of the disclosed concept, a component for an electric power system is provided. The component comprises: a user access panel; a first element for directing visible light, the first element having a first end and a second end, the first end of the first element terminating at or proximate the user access panel; a second element for directing visible light, the second element having a first end and a second end, the first end of the second element terminating at or proximate the user access panel, the second end of the first element facing the second end of the second element; a movable conductor structured to move between a first position and a second position; and a stationary conductor structured to engage the movable conductor. In the first position the movable conductor is disposed between the second end of the first element and the second end of the second element, thereby blocking visible light from passing from the first element to the second element. In the second position the movable conductor is not disposed between the second end of the first element and the second end of the second element, thereby permitting visible light to pass from the first element to the second element. 
     As another aspect of the disclosed concept, a component for an electric power system is provided. The component comprises: a user access panel comprising a user input member; a first element for directing visible light, the first element having a first end and a second end, the first end of the first element terminating at or proximate the user access panel; a second element for directing visible light, the second element having a first end and a second end, the first end of the second element terminating at or proximate the user access panel, the second end of the first element facing the second end of the second element; a light source disposed at or proximate the user access panel, the light source being structured to be energized in response to activation of the user input member and pass visible light to the first end of the first element; a movable conductor structured to move between a first position and a second position; and a stationary conductor structured to engage the movable conductor. In the first position the movable conductor is disposed between the second end of the first element and the second end of the second element, thereby blocking visible light from passing from the first element to the second element. In the second position the movable conductor is not disposed between the second end of the first element and the second end of the second element, thereby permitting visible light to pass from the first element to the second element. 
     As another aspect of the disclosed concept, a method of determining whether a power circuit in an electric power system is open or closed is provided. The electric power system comprises a component; the component comprises a user access panel, a stationary conductor, and a movable conductor structured to engage the stationary conductor; the power circuit is closed when the movable conductor engages the stationary conductor; the power circuit is open when the movable conductor does not engage the stationary conductor; and the movable conductor is structured to move between a first position and a second position. The method comprises: providing a first element for directing visible light, the first element having a first end and a second end; terminating the first end of the first element at or proximate the user access panel; providing a second element for directing visible light, the second element having a first end and a second end; terminating the first end of the second element at or proximate the user access panel; providing the second end of the first element facing the second end of the second element; disposing the movable conductor between the second end of the first element and the second end of the second element in the first position but not the second position; passing visible light into the first end of the first element; and either exiting the visible light from the first end of the second element when the movable conductor is in the second position, or blocking the visible light from entering the second end of the second element when the movable conductor is in the first position. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       A full understanding of the disclosed concept can be gained from the following description of the preferred embodiments when read in conjunction with the accompanying drawings in which: 
         FIG. 1  is a front isometric view of a load break switch. 
         FIG. 2  is a side view, partially cut away, of the load break switch of  FIG. 1 . 
         FIG. 3  is a front isometric view, partially cut away, of a load break switch in accordance with an embodiment of the disclosed concept. 
         FIG. 4A  is an isometric view of a portion of the load break switch of  FIG. 3 . 
         FIG. 4B  is an isometric view of a portion of  FIG. 4A . 
         FIG. 5A  is a schematic view of a light source in accordance with an embodiment of the disclosed concept. 
         FIG. 5B  is a schematic view of another light source in accordance with another embodiment of the disclosed concept. 
         FIG. 6  is an isometric view of a portion of the load break switch of  FIG. 3  in a closed position. 
         FIG. 7  is an isometric view of a portion of the load break switch of  FIG. 3  in an open position. 
         FIG. 8  is a front isometric view of a load break switch. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     As employed herein, the term “number” shall mean one or an integer greater than one (i.e., a plurality). 
     As employed herein, the statement that two or more parts are “connected” or “coupled” together shall mean that the parts are joined together either directly or joined through one or more intermediate parts. 
     As employed herein, the statement that two or more parts or components “engage” one another shall mean that the parts touch and/or exert a force against one another either directly or through one or more intermediate parts or components. 
       FIGS. 1 and 2  show a load break switch  100 . As seen in  FIG. 2 , the load break switch  100  includes a movable conductor  110  that engages a stationary conductor  120  in a first position and does not engage the stationary conductor  120  in a second position (shown in phantom line drawing). The load break switch  100  also includes a lever  115  that is structured to move in a direction  116  upon activation by a user. 
     The load break switch  100  is part of an electric power system (not shown) that has a power circuit. When the movable conductor  110  engages the stationary conductor  120 , the power circuit is closed and current can flow. When the movable conductor  110  does not engage the stationary conductor  120 , the power circuit is open and current cannot flow. The load break switch  100  further includes a housing (see, for example, housing  105 , partially shown in  FIG. 1 ) which prevents a user from determining whether the movable conductor  110  is engaging the stationary conductor  120  or not (i.e., whether the power circuit is open or closed). 
     As will be discussed in connection with  FIGS. 3, 4A, 4B, 5A, 5B, 6 and 7 , a load break switch  200  allows for visible indication of power circuit status within an electric power system (not shown). Except as will be described, the load break switch  200  can be similar to the load break switch  100  of  FIGS. 1 and 2 . The load break switch  200  includes a number of movable conductors  210  that are structured to engage a number of stationary conductors  220  in a first position, as shown. In an electric power system including the load break switch  200 , when the movable conductors  210  are in the first position, a corresponding number of power circuits are closed. 
     The load break switch  200  further includes a lever  215  and upon activation of the lever  215  by a user, the movable conductors  210  move from the first position to a second position (see, for example,  FIG. 7 ). In the second position, the movable conductor  210  does not engage the stationary conductor  220  and the corresponding power circuit is open. Partially shown in  FIG. 3 , the load break switch  200  includes a housing  205  which interferes with the ability to visibly determine power circuit status within the load break switch  200 . However, unlike the load break switch  100  of  FIGS. 1 and 2 , visible indication of power circuit status within the load break switch  200  can be determined by employing one of a number of light sources  260  ( FIG. 5A ), 270  ( FIG. 5B ) with a user access panel  250  ( FIG. 3 ), a number of elements  230 , 235  ( FIG. 3 ), and a member  240  ( FIG. 3 ) internal to the housing  205 . 
       FIG. 4A  shows the user access panel  250 , the elements  230 , 235  and the member  240 . As seen, the first element  230  includes a first end  232  and a second end  234 . Similarly, the second element  235  includes a first end  237  and a second end  239 . The first ends  232 , 237  terminate at or proximate the user access panel  250 . The member  240  includes a first surface  242  and a second surface  244  opposite the first surface  242 . As seen, the second end  234  of the first element  230  terminates at or proximate the first surface  242  of the member  240 . The second end  239  of the second element  235  terminates at or proximate the second surface  244  of the member  240  and faces the second end  234  of the first element  230 . Optionally, in one embodiment, as seen in  FIGS. 4A and 4B , the user access panel  250  includes a user input member  252 . 
     In the example embodiment, the elements  230 , 235  are fiber optic cables that direct visible light. Schematically shown in  FIG. 5A , a light source  260  is structured to be located at or proximate the first end  232  of the first element  230  at the user access panel  250 . The light source  260  includes a voltage source  262 , a resistor  264 , a diode  266 , and a switch  268  electrically connected in series to a ground  269 . Upon activation of the user input member  252 , the light source  260  is structured to be energized by the switch  268  and pass visible light into the first end  232  of the first element  230 . 
     Schematically shown in  FIG. 5B  is another example light source  270  that is a flashlight. In accordance with an alternative embodiment of the disclosed concept, a user shines the light source  270  into the first end  232  of the first element  230 . Referring to  FIGS. 4A, 4B, 5A, and 5B , when either of the light sources  260 , 270  pass visible light into the first element  230  and nothing is disposed between the first surface  242  and the second surface  244  of the member  240 , the visible light exits the first end  237  of the second element  235 . Hence, by viewing the visible light exiting from the first end  237 , the user knows in this example, that the corresponding power circuit is open (and is not energized). 
     As seen in  FIG. 6 , the movable conductor  210  engages the stationary conductor  220  in the first position. In this manner, the power circuit within the electric power system (not shown) is closed. In accordance with the disclosed concept, when a user activates the user input member  252  or shines the light source  270  into the first end  232  of the first element  230 , visible light is passed into the first element  230 . Continuing to refer to  FIG. 6 , the movable conductor  210  is located between the second end (see, for example, second end  234  in  FIG. 4A ) of the first element  230  and the second end (see, for example, second end  239  in  FIG. 4A ) of the second element  235  in the first position. 
     Thus, in the first position (e.g., as shown in  FIG. 6 ), the movable conductor  210  blocks visible light from passing from the first element  230  to the second element  235 . In operation, when a user activates the user input member  252  or shines the light source  270  into the first end  232  of the first element  230  and does not see visible light exit the first end  237  of the second element  235 , the user will be able to determine that the movable conductor  210  is in the first position. In other words, the user will know by not seeing the visible light at the first end  237  of the second element  235  that the movable conductor  210  is engaging the stationary conductor  220 , that the corresponding power circuit is closed (and energized), and that it is not safe to access the power circuit controlled by the load break switch  200 . 
       FIG. 7  shows the movable conductor  210  in the second position, not located between the ends  234 , 239  of  FIG. 4A . In this manner, when a user activates the user input member  252  or shines the light source  270  into the first end  232  of the first element  230 , visible light is permitted to pass from the first element  230  to the second element  235 . Thus, in the second position, the visible light is permitted to exit the first end  237  of the second element  235  and indicate to a user that the movable conductor  210  is in the second position. In other words, the user will know by seeing the visible light at the first end  237  of the second element  235  that the movable conductor  210  is not engaging the stationary conductor  220 , that the power circuit is open (and not energized), and that it is safe to access the power circuit controlled by the load break switch  200 . 
     The disclosed concept has been described in association with the example load break switch  200 . However, other load break switches (see, for example, load break switch  300 , shown in  FIG. 8 ) can be suitably modified within the scope of the disclosed concept. As seen in  FIG. 8 , the load break switch  300  differs from the load break switch  100  in size and shape, but is similar in that it includes a number of movable conductors  310  that engage a number of stationary conductors  320  in a first position. Upon activation of a lever  315  by a user, the movable conductors  310  are structured to move to a second position (not shown) and not engage the stationary conductors  320 . The load break switch  300  also includes a housing (see, for example, housing  305 , partially shown in  FIG. 8 ), that prevents visible indication of power circuit status within the load break switch  300 . 
     Although not shown in  FIG. 8 , it is within the scope of the disclosed concept for the load break switch  300  to be modified to employ one of a number of light sources with a user access panel, elements, and a member for indication of power circuit status within an electric power system (not shown) substantially similar to the light sources  260 , 270 , user access panel  250 , elements  230 , 235 , and member  240  of the load break switch  200 . Accordingly, it will be appreciated that visible indication of power circuit status within the load break switch  300  can be determined in the same manner as discussed above in association with the load break switch  200 . 
     For example and without limitation, light sources, user access panels, elements, and members substantially similar to those set forth above may be employed with other components, including other circuit interrupters and electrical switching apparatus. Additionally, although the disclosed concept has been described in association with the member  240  being mounted within the load break switch  200  in the location shown in  FIGS. 3, 6, and 7 , it is within the scope of the disclosed concept for the member  240  to be mounted in other locations. 
     For example and without limitation, it is within the scope of the disclosed concept for the movable conductor  210  to be in the second position ( FIG. 7 ) and be located between opposite surfaces of a member (not shown) such that in the second position, the movable conductor  210  blocks visible light from passing from a first element (not shown) to a second element (not shown) and in the first position the movable conductor  210  does not block visible light from passing from the first element to the second element. Additionally, it is within the scope of the disclosed concept to have the second ends  234 , 239  face each other and not have the example member  240  mounted within the load break switch  200 . 
     While specific embodiments of the disclosed concept have been described in detail, it will be appreciated by those skilled in the art that various modifications and alternatives to those details could be developed in light of the overall teachings of the disclosure. Accordingly, the particular arrangements disclosed are meant to be illustrative only and not limiting as to the scope of the disclosed concept which is to be given the full breadth of the claims appended and any and all equivalents thereof.