Abstract:
An overhead conductor sensor for measuring various parameters that affect an overhead conductor is disclosed. The overhead conductor sensor includes an electronics housing having first and second opposing ends, a jaw assembly having a first jaw connected to the first end of the electronics housing and a second jaw pivotally attached to the first jaw to allow the jaw assembly to move between an open position for receiving an overhead conductor therein and a closed position for securing the sensor to the overhead conductor, and a thermocouple assembly electrically connected to electronics housed in the electronics housing and extending through the jaw assembly for engagement with the overhead conductor. The thermocouple assembly is adapted to measure a temperature of the overhead conductor.

Description:
[0001]    This application claims the benefit of Provisional Application No. 61/510,154 filed on Jul. 21, 2011. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    This application relates to an overhead conductor sensor for measuring various parameters that affect an overhead conductor and indicate or troubleshoot potential failures in the conductor of its components. 
         [0003]    With an ever-increasing need for electric utilities to transfer more power through existing power lines, utilities must take into account various factors. One such factor is sag in the conductor. As power loads increase, conductors sag due to increased temperatures in the conductor which causes thermal expansion. Since a sagging conductor may cause clearance and safety issues, making sure the conductor does not go beyond reasonable sag is of the up most importance. Other factors include failing connectors and vibrating or galloping conductors. In addition, other parameters become of importance when dealing with the above factors, such as ambient air temperature and wind speed and direction. 
         [0004]    It is challenging to measure conductor and connector parameters on an overhead transmission line as the conductor is energized up to 765 kV and above. Accordingly, there is a need for an overhead conductor sensor that can measure parameters of an overhead conductor to indicate failing connectors, troubleshoot vibrating or galloping conductors, dynamically rate conductors, aid in conductor location surveys, and know what the current is flowing in the conductor. 
       BRIEF SUMMARY OF THE INVENTION 
       [0005]    These and other shortcomings of the prior art are addressed by the present invention, which provides an overhead conductor sensor that is of lower cost, has a low power consumption design, includes power harvesting capabilities, has an increased temperature measurement accuracy, and is easy to install. Further, the overhead conductor sensor is easy to install on an energized conductor, does not impact conductor temperatures via thermal heat sinking or wind sheltering, adjusts to different conductor sizes, and uses plug and play communications options to allow for upgrading and the use of different communications equipment. 
         [0006]    According to one aspect of the present invention, an overhead conductor sensor includes an electronics housing having first and second opposing ends, a jaw assembly having a first jaw connected to the first end of the electronics housing and a second jaw pivotally attached to the first jaw to allow the jaw assembly to move between an open position for receiving an overhead conductor therein and a closed position for securing the sensor to the overhead conductor, and a thermocouple assembly electrically connected to electronics housed in the electronics housing and extending through the jaw assembly for engagement with the overhead conductor. The thermocouple assembly is adapted to measure a temperature of the overhead conductor. 
         [0007]    According to another aspect of the invention, an overhead conductor sensor includes an electronics housing having first and second opposing ends, a jaw assembly, and a thermocouple assembly. The electronics housing houses first and second electronic boards. The jaw assembly includes a first jaw connected to the first end of the electronics housing and a second jaw pivotally attached to the first jaw to allow the jaw assembly to move between an open position for receiving an overhead conductor therein and a closed position for securing the sensor to the overhead conductor, and a clamping assembly having first and second clamping mechanisms. The first clamping mechanism is connected to the first jaw and the second clamping mechanism is adjustably mounted to the second jaw to allow the clamping assembly to receive and provide a clamping force around overhead conductors of varying diameters, thereby securing the sensor to the overhead conductor. The thermocouple assembly is electrically connected to the first electronics board and extends through an aperture of the first clamping mechanism for engagement with the overhead conductor. The thermocouple assembly is adapted to measure a temperature of the overhead conductor. 
         [0008]    According to another aspect of the invention, an overhead conductor sensor includes an electronics housing having first and second opposing ends, a jaw assembly, and a thermocouple assembly. The electronics housing houses first and second electronic boards. The jaw assembly includes a first jaw connected to the first end of the electronics housing and a second jaw pivotally attached to the first jaw to allow the jaw assembly to move between an open position for receiving an overhead conductor therein and a closed position for securing the sensor to the overhead conductor, and a clamping assembly having first and second clamping mechanisms. The first clamping mechanism is connected to the first jaw and the second clamping mechanism is adjustably mounted to the second jaw to allow the clamping assembly to receive and provide a clamping force around overhead conductors of varying diameters, thereby securing the sensor to the overhead conductor. The thermocouple assembly is electrically connected to the first electronics board and extends through an aperture of the first clamping mechanism for engagement with the overhead conductor. The thermocouple assembly is adapted to measure a temperature of the overhead conductor and includes a thermocouple having first and second ends, a thermocouple tip, an insulator bushing, and a spring. The first end of the thermocouple is electrically connected to the first electronics board and the second end extends through the aperture. The thermocouple tip is attached to the second end of the thermocouple and includes an expandable central bore for receiving and clamping around the second end of the thermocouple. The insulator bushing is positioned between the thermocouple tip and the first clamping mechanism to prevent the tip from being pushed through the aperture by an overhead conductor. The spring is positioned between the bushing and a stop positioned in the first jaw to provide a mechanical force to the bushing, thereby pressing the tip into the overhead conductor being measured. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0009]    The subject matter that is regarded as the invention may be best understood by reference to the following description taken in conjunction with the accompanying drawing figures in which: 
           [0010]      FIG. 1  is a perspective view of an overhead conductor sensor according to an embodiment of the invention; 
           [0011]      FIG. 2  is another perspective view of the sensor of  FIG. 1 ; 
           [0012]      FIG. 3  shows a bonding electrode for use with the sensor of  FIG. 1 ; 
           [0013]      FIG. 4  is another perspective view of the sensor of  FIG. 1 ; 
           [0014]      FIG. 5  is a bottom view of the sensor of  FIG. 1 ; 
           [0015]      FIG. 6  is another perspective view of the sensor of  FIG. 1  showing a jaw assembly of the sensor; 
           [0016]      FIG. 7  shows an upper clamping mechanism of the jaw assembly of  FIG. 6 ; 
           [0017]      FIG. 8  shows the upper and lower clamping mechanisms of the jaw assembly of  FIG. 6 ; 
           [0018]      FIGS. 9 and 10  show electronics contained in an electronics housing of the sensor of  FIG. 1 ; 
           [0019]      FIG. 11  shows a thermocouple assembly connected to the electronics of  FIGS. 9 and 10 ; 
           [0020]      FIGS. 12 and 13  show the thermocouple assembly of  FIG. 11  connected with the jaw assembly of  FIG. 6 ; 
           [0021]      FIG. 14  is a perspective of the thermocouple assembly of  FIG. 11 ; and 
           [0022]      FIG. 15  shows a tip of the thermocouple assembly engaging a conductor. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0023]    Referring to the drawings, an exemplary overhead conductor sensor according to an embodiment of the invention is illustrated in  FIG. 1  and shown generally at reference numeral  10 . The sensor  10  includes an electronics housing  11  having a first end  12  connected to a jaw assembly  13  and a second opposing end  14  connected to a stabilizer  16 . All edges of conductive components are rounded to ensure that the electrical field magnitudes are low, thereby preventing corona activity. Further, the sensor is filled with an epoxy compound to provide environmental protection. 
         [0024]    As shown in  FIG. 2 , the jaw assembly  13  includes a socket  23  for allowing a hot stick (not shown) and a bonding electrode  24 ,  FIG. 3 , to be attached to the sensor  10  by a mating fastener. The hotstick allows the sensor  10  to be placed onto an energized conductor and the bonding electrode  24  ensures that an arc does not go through the sensor. The hotstick and bonding electrode are removed after installation. 
         [0025]    Referring to  FIG. 4 , the stabilizer  16  is removably attached to the housing  11  and is adapted for use in vibration installations. The stabilizer  16  includes a plurality of slots  25  for receiving a conductor. The slots  25  are conductor size specific, i.e., each slot is sized for a specific size of conductor. As shown, the stabilizer  16  includes two different sized slots  25  to accommodate two different sized conductors. However, it should be appreciated, that the stabilizer  16  may include additional slots to accommodate a greater number of conductors. For example, the stabilizer could be cross-shaped to accept four different sized conductors. To accommodate a different sized conductor, the stabilizer  16  is simply rotated to the slot  25  that matches the conductor size. 
         [0026]    Referring to  FIGS. 5-8 , the jaw assembly  13  includes a first jaw  17  pivotally attached to a second jaw  18  via pivot joint  19  to allow the jaw assembly  13  to move between an open position, to receive a conductor therein, and closed position, to secure the sensor  10  to a conductor  20 ,  FIG. 1 . The jaw assembly  13  is secured in the closed position by a fastener  21  which extends through the first and second jaws  17 ,  18 . The fastener  21  may be tightened by a standard wrench or socket type tool. 
         [0027]    The jaw assembly  13  further includes an adjustable clamping assembly  22  having first and second clamping mechanisms  26 ,  27 . Both clamping mechanisms  26  and  27  include a concave inner surface  28  and  29  to complement the rounded outside surface of the conductor  20 . The inner surfaces  28  and  29  also include a plurality of steps  30  and  31  that act like teeth to secure the sensor  10  to the conductor  20 . Together, the concave inner surfaces  28 ,  29  and steps  30 ,  31  of the clamping mechanisms  26 ,  27  allow the clamping assembly  22  to mate with and secure the sensor  10  to various sized conductors, i.e., conductors of different diameters. As shown, the clamping assembly  22  is made of a thermoplastic; however, other suitable materials may be used. 
         [0028]    Referring specifically to  FIGS. 7 and 8 , clamping mechanism  27  includes elongated slots  32  and  33  adapted to receive fasteners  34  and  36  therethrough. The slots  32 ,  33  allow the clamping mechanism  27  to be slidably mounted to jaw  18  to allow the clamping assembly  22  to be moved from a non-clamping position, to receive conductors of varying diameters, to a clamping position to secure the sensor  10  to the conductor,  FIG. 1 . 
         [0029]    Referring to  FIGS. 9 and 10 , the electronics housing  11  includes a coil  40 , a battery  41 , a first electronic board  42 , a second electronic board  43 , an antenna  44  and matching strip-line PCB board  46 . The coil  40  includes a ferrite core with windings wrapped around the core and is adapted to couple with a magnetic field from the conductor  20  to harvest power therefrom and to measure the amount of current flowing through the conductor  20 . As shown, the battery  41  is a non-reachargeable battery and provides power to the sensor  10  when there is no or low current flowing through the conductor. The battery will last 2 years with no power. It should be appreciated that the battery may also be a rechargeable battery adapted to be recharged by the coil  40  when needed. 
         [0030]    The first electronic board  42  performs power harvesting, measurement and processing, storage of signals, and controls the whole measurement communications process. The board  42  has as inputs for voltage from the coil  40  and a thermocouple assembly  50 , shown in  FIG. 11 . The board  42  measures the voltage from the coil  40  to get a measurement of current flowing through the conductor  20 . The voltage from the coil  40  is also harvested to power the sensor  10  (if high enough—if too low switches to battery  41 ). The board  42  also includes a 3D accelerometer chip which takes samples from DC to 2000 samples per second. 
         [0031]    The second electronic board  43  is an RF transmitter. The board  43  is adapted for plug and play so that different RF boards can be utilized to enable different communications protocols, frequencies, and/or methods. The board  43  provides for two way RF communications to allow firmware of the sensor  10  to be updated or reset and to allow data to be downloaded from the sensor  10  to a remote location having computers or processors with software adapted to perform specified calculations. All of the electronics and RF communications are designed to be very low power to enable power harvesting and long battery life. 
         [0032]    The antenna  44  includes a stalk  47  that extends through the housing  11  and an antenna ball  48  and is electrically connected to the board  43 . The diameter of the ball and the height of the stalk are optimized for both RF transmission and omni-directional beam pattern. Further, the shape of the antenna ball is optimized to prevent corona. The matching strip-line PCB board  46  is electrically connected to the antenna  44  and sits behind the antenna  44  to ensure that power is fully transmitted to the antenna  44 . 
         [0033]    Referring to  FIGS. 11-14 , a thermocouple  50  assembly is electrically connected to the first electronic board  42  and is adapted to measure conductor temperature. The thermocouple assembly  50  includes a thermocouple  51 , a thermocouple tip  52  which houses a portion of the thermocouple  51 , an insulator bushing  53  positioned adjacent to or behind the tip  52 , a spring  54  positioned adjacent to or behind the bushing  53 , and a plug and play connector  56  to electrically connect the thermocouple  51  to the board  42 . The thermocouple assembly  50  is the only thermal and electrically conductive component in contact with the conductor  20  to prevent heat sinking and to enable a single point ground so that currents do not flow through the sensor  10 . 
         [0034]    As shown in  FIG. 12 , the thermocouple assembly  50  is engaged with clamping mechanism  26  such that the thermocouple tip  52  extends through an aperture  58  in the clamping mechanism  26  for contact with the conductor  20 . Because the clamping mechanism  26  is made from thermoplastic, it provides insulation between the jaw assembly  13  and the conductor  20 , thereby preventing heat sinking. In addition, the thermocouple tip  52  is insulated from the jaw assembly  13  by the insulator bushing  53 . 
         [0035]    As illustrated in  FIG. 14 , the thermocouple tip  52  has a slot  60  machined in one side of the tip  52 . In assembling the tip  52  onto the thermocouple  51 , a feeler gauge or other suitable device is inserted into the slot  60  to open up a central bore  61  of the tip  52 . The thermocouple  51  is then inserted into the bore  61  and the feeler gauge is removed from the slot  60 , resulting in a mechanical clamping force by the tip  52  around the thermocouple  51 . The bore  61  is then filled with an epoxy or other suitable compound to provide a second mechanical attachment. 
         [0036]    As shown, the bushing  53  includes a first cylindrical portion  62  for mating with the tip  52 , a second larger cylindrical portion  63  to engage the clamping mechanism  26 ,  FIG. 12 , and provide a stop so that the bushing  53  cannot be pushed through the aperture  58  and to provide a surface for the spring  54  to push against, and a third cylindrical portion  64  sized to mate with an inner diameter of the spring  54  and adapted to hold the spring  54  in position by extending into an inner bore of the spring  54 . The spring  54  is positioned between the bushing  53  and a stop  66  to provide a mechanical force to the bushing  53 , thereby shoving the tip  52  into the conductor  20  or connector (not shown) being measured. 
         [0037]    As illustrated in  FIG. 15 , the shape of the tip  52  is pointed so that it will locate itself between conductor strands. In addition, aperture  58  is sized to be slightly larger than the diameter of the tip  52  and first cylindrical portion  62  of the bushing  53  to allow play so that the tip  52  can move side-to-side and ensure that the tip  52  falls between the strands. 
         [0038]    In operation, the sensor  10  can perform on board measurements and algorithms/calculations for present conductor and ambient temperature—rolling average, present current, maximum temperature, current at the time of maximum temperature, histogram of temperatures (# of minutes/hour in a specific temperature range), inclination in three axes, raw vibration waveforms in three axes—10 second clips, Fast Fourier Transform of the waveform to provide frequency content of vibration waveform, and Calculate displacement from the acceleration measured. 
         [0039]    The foregoing has described an overhead conductor sensor. While specific embodiments of the present invention have been described, it will be apparent to those skilled in the art that various modifications thereto can be made without departing from the spirit and scope of the invention. Accordingly, the foregoing description of the preferred embodiment of the invention and the best mode for practicing the invention are provided for the purpose of illustration only and not for the purpose of limitation.