Abstract:
An inspection apparatus for inspecting high voltage insulators is disclosed. The inspection apparatus includes a first platform having first and second linkages, at least one outer gripping mechanism having first and second arms extending outwardly from the first platform, a second slidable platform adapted to slide along the first and second linkages, and at least one inner gripping mechanism having third and fourth arms extending outwardly from the second slidable platform. The outer and inner gripping mechanisms are adapted to move between an open position where the insulator is received by the outer and inner gripping mechanisms and a closed position where the outer and inner gripping mechanisms engage the insulator.

Description:
BACKGROUND OF THE INVENTION 
     This application claims the benefit of Provisional Application No. 61/525,782 filed on Aug. 21, 2011. 
    
    
     This application relates to an apparatus and method for inspecting high voltage insulators and, more particularly, to a self contained inspection robot for inspecting high voltage insulators. 
     Inspecting, evaluating, and maintaining transmission and distribution insulators is challenging due to the associated high voltages and large inspection distances. This is particularly challenging for non-ceramic insulators (NCI) which requires a user to confirm the short-term electrical and mechanical integrity of both the installed and the replacement units. 
     One of the primary inspection methods used today is visual/camera inspection. This is often challenging due to poor lighting, challenging angles of inspection, and long inspection distances. Other inspection methods require contact to be made with the insulator. This is often done by securing an inspection tool to the end of a hotstick which is manipulated by a human operator from a bucket truck. Utilizing an inspection tool from a hotstick creates a situation (1) that is challenging due to the high cantilever loads the operator has to manage, (2) that introduces uncertainty due to operator error in positioning the unit, and (3) that requires the operator to be close to the energized conductors which creates a potentially hazardous environment (live work). 
     BRIEF SUMMARY OF THE INVENTION 
     These and other shortcomings of the prior art are addressed by the present invention, which provides an apparatus and method for inspecting high voltage insulators that provide proper inspection of an insulator without creating a hazardous environment. 
     According to an aspect of the invention, an inspection apparatus for inspecting high voltage insulators includes a first platform having first and second linkages, at least one outer gripping mechanism having first and second arms extending outwardly from the first platform, a second slidable platform adapted to slide along the first and second linkages, and at least one inner gripping mechanism having third and fourth arms extending outwardly from the second slidable platform. The outer and inner gripping mechanisms are adapted to move between an open position where the insulator is received by the outer and inner gripping mechanisms and a closed position where the outer and inner gripping mechanisms engage the insulator. 
     According to another aspect of the invention, an inspection apparatus for inspecting high voltage insulators spaced-apart first and second outer gripping mechanisms extending outwardly from a first platform and interconnected by at least one linkage such that the first and second outer gripping mechanisms move from an open position for receiving an insulator to a closed position for engaging the insulator simultaneously, and spaced-apart first and second inner gripping mechanisms positioned between the first and second outer gripping mechanisms. The first and second inner gripping mechanisms extend outwardly from a moveable second platform and are interconnected by a gear drive such that the first and second inner gripping mechanisms move from an open position for receiving the insulator to a closed position for engaging the insulator simultaneously. The second platform is slidably connected to the at least one linkage to allow the first and second inner gripping mechanisms to move along the linkage between the first and second outer gripping mechanisms and allow the inspection apparatus to traverse an insulator. 
     According to another aspect of the invention, a method for inspecting high voltage insulators includes the steps of providing an inspection apparatus having at least one outer gripping mechanism extending outwardly from a first platform, at least one inner gripping mechanism extending outwardly from a second platform, and at least one sensor contained in the outer gripping mechanism. The second platform is slidable along a linkage of the first platform. The method further includes the steps of placing the inspection apparatus on the insulator to be inspected, moving the at least one outer gripping mechanism and at least one inner gripping mechanism to a closed position to secure the inspection apparatus to the insulator, and using the at least one sensor to determine conductive and high permittivity defects in the insulator. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       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: 
         FIG. 1  is a perspective view of an apparatus according to an embodiment of the invention; 
         FIG. 2  shows drive assembly of inner gripping mechanisms of the apparatus of  FIG. 1 ; 
         FIG. 3  shows drive assembly of outer gripping mechanism of the apparatus of  FIG. 1 ; 
         FIG. 4  shows drive assembly of screw gear of the apparatus of  FIG. 1 ; 
         FIG. 5  shows a rear perspective of the apparatus of  FIG. 1 ; 
         FIG. 6  shows the apparatus of  FIG. 1  with inner mechanisms open and in a lower position; 
         FIG. 7  shows the apparatus of  FIG. 1  with the inner mechanisms open and in an upper position; 
         FIG. 8  shows all of the gripping mechanisms of the apparatus of  FIG. 1  in a closed position; 
         FIG. 9  shows the apparatus of  FIG. 1  with outer mechanisms open and the inner mechanisms in an upper position; 
         FIG. 10  shows the apparatus of  FIG. 1  with the outer mechanisms open and the inner mechanisms in a lower position; 
         FIG. 11  shows an arm of the apparatus of  FIG. 1  with a sensor embedded in a grip of the arm; 
         FIG. 12  shows the apparatus of  FIG. 1  with electronics carried thereupon; and 
         FIG. 13  shows an alternate embodiment of the apparatus of  FIG. 1  using tracks to move the apparatus along an insulator. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring to the drawings, an exemplary inspection apparatus in the form of a robot according to an embodiment of the invention is illustrated in  FIGS. 1-5  and shown generally at reference numeral  10 . 
     In general, the robot  10  is self contained and is clipped on an insulator. An operator is then able to move away from a hazardous environment and control the robot  10  using a wireless link. The robot  10  may include inspection technologies such as a close up camera, permittivity/conductivity sensors, and any other desired inspection technology (infra-red, NCI tools, ultrasonic, etc). This enables (1) the operator to have reduced exposure to hazardous environments; (2) the inspection distance, especially for optical devices to be small; and (3) inspection tools that require contact to be applied in a more consistent manner. 
     The robot  10  includes outer  11 ,  12  and inner  13 ,  14  gripping mechanisms for gripping onto an insulator. For simplicity, only gripping mechanism  11  will be discussed; however, it should be appreciated that gripping mechanisms  12 ,  13 , and  14  have the same basic structure and that the discussion relating to mechanism  11  also applies to mechanisms  12 ,  13 , and  14 . Further, it should be appreciated that like numbers or prime numbers are intended to identify similar structures. 
     The gripping mechanism  11  includes a pair of arms  16  and  17  extending outwardly from a main platform  18  of the robot  10 . When in a closed position, the arms  16  and  17  are substantially parallel to each other. Each arm  16  and  17  includes a gripping device  20 ,  21  attached thereto for securing the robot to an insulator. The gripping devices  20 ,  21  have a concave section  22  that may be U-shaped, V-shaped or any other complementary shape to allow the devices  20 ,  21  to “mate” with a cylindrical sheath section of an insulator. The arms  16  and  17  may be made out of fiberglass and the gripping devices  20  and  21  may be made of a non-conductive plastic. However, it should be appreciated that other suitable materials may be used to reduce corona issues, reduce the impact of the local electric field, and reduce the portion of the insulator that is electrically compromised by the presence of the robot  10 . It should also be appreciated that various sensing technologies such as visual and infra-red inspection devices, voltage and current sensors, ultrasonic inspection devices, etc. may be embedded into the concave section  22  of the gripping devices  20  and  21 . 
     Each of the arms  16  and  17  are individually hinged to the platform  18  by pivots  15  to allow the arms  16  and  17  to pivot from a closed position,  FIG. 1 , where the robot  10  is secured to an insulator, to an open position,  FIGS. 6-10 , to allow the robot  10  to be positioned onto an insulator. 
     Referring, particularly, now to outer gripping mechanisms  11  and  12 , the outer gripping mechanisms  11  and  12  are mechanically joined together using linkages  26  and  27 . The linkages  26  and  27  ensure that the gripping mechanisms  11  and  12  open and close simultaneously. As shown, linkage  26  interconnects arms  16  and  16 ′ and linkage  27  interconnects arms  17  and  17 ′. The linkages  26  and  27  are driven by gears  28  and  29  which are driven by an electric motor  30 . The gears  28  and  29  interact with gears  31  and  32 , respectively, to rotate the linkages  26  and  27 . As the linkages  26  and  27  are rotated, gears  33  and  34  interact with gears  36  and  37  to move arms  16  and  17 . At the same time, arms  16 ′ and  17 ′ are moved by gears  38  and  39 , which are directly connected to gears  28  and  29  to enact simultaneous movement. 
     Referring, particularly, now to inner gripping mechanisms  13  and  14 , the inner gripping mechanisms  13  and  14  are connected to a slidable platform  40  that is adapted to slide along linkages  26  and  27 . Like gripping mechanisms  11  and  12 , gripping mechanisms  13  and  14  are adapted to move simultaneously with each other. The arms  16 ″,  16 ″′ and  17 ″,  17 ″′ move from an closed position,  FIG. 1 , to an open position,  FIGS. 6-10 , by a worm drive  41  which interacts with gears  42  and  43 . The worm drive  41  is driven by electric motor  44 . Gear  42  drives both arms  17 ″ and  17 ″′ using linkage  46  and gear  43  drives both arms  16 ″ and  16 ″′ using linkage  47  to ensure simultaneous movement of the arms. 
     As discussed, the platform  40  is adapted to slide along linkages  26  and  27 . The platform  40  is driven by a screw gear  48  connected to the platform  40 . The screw gear  48  is driven by electric motor  50  which interacts with gear  51  to drive the screw gear  48 . As the screw gear  48  is rotated by the motor  50 , the platform moves either up or down along the linkages  26  and  27  depending the direction of the motor. 
     Referring to  FIGS. 6-10 , outer  11 ,  12  and inner  13 ,  14  gripping mechanisms are adapted to move relative to each other. For example, the inner  13 ,  14  mechanisms may be in an open position while the outer  11 ,  12  mechanisms are in a closed position,  FIG. 6 . Also, the inner  13 ,  14  mechanisms may move from a lower position,  FIG. 6 , to a higher position,  FIG. 7 . As shown in  FIGS. 9 and 10 , the outer  11 ,  12  mechanisms may be in an open position while the inner  13 ,  14  mechanisms are in a closed position. When the two of the individual arms are in the closed position they clamp around the sheath of the insulator mechanically attaching the robot to insulator. 
     The robot moves up and down the insulator in the following manner:
         (1) The robot is placed on the insulator and the outer mechanisms  11 ,  12  simultaneously are closed so that they grip on to the sheath of the insulator. The weight is held by these two mechanisms.   (2) The inner gripping mechanisms  13 ,  14  are open and are close to the lower side of the robot  10 . The inner gripping mechanisms  13 ,  14  are then moved along the linkages  26  and  27  by the screw gear  48  and motor  50  until they get to the upper side of the robot  10  (or some distance between the lower and upper side.   (3) The inner gripping mechanisms  13 ,  14  then simultaneously close. The weight of the robot  10  is then held by both the inner  13 ,  14  and outer  11 ,  12  gripping mechanisms.   (4) The outer gripping mechanisms  11 ,  12  then simultaneously open. The weight of the robot  10  is now held by the inner gripping mechanisms  13 ,  14 .   (5) The inner gripping mechanisms  13 ,  14  are then moved along the linkages  26  and  27  by screw gear  48  and motor  50  until they reach the lower side of the robot, thereby, moving the entire robot  10  along the insulator.   (6) The outer gripping mechanisms  11 ,  12  then close and the process repeats as the robot  10  moves up and down the insulator.       

     The robot  10  enables inspection of vertical and horizontal insulators and of insulators positioned at any angle therebetween. 
     Micro-switches (not shown) tell the robot  10  when the gripping mechanisms  11 - 14  are fully open and closed. The robot  10  also knows that the arms are fully closed by measuring the torque (current and voltage) that the electric motor is consuming. The movement up and down the insulator can be automated and controlled by electronics by: (1) knowing the exact shed and sheath spacing and (2) optical (LED and photodiodes) and imaging sensors (cameras with image processing) that identify the presence of sheds and sheath sections. And know when to open and close. 
     The robot  10  has an onboard rechargeable battery. Control of the robot  10  and the collection of inspection data is performed or communicated by an RF link. The control can be completely manual—when an operator controls the robot arms, etc.; completely automatic; or a combination thereof—e.g. the operator tells the robot to move 15 inches and make measurements and it executes. Optical cameras may be mounted on the arms or the main platform  18 . 
     Referring to  FIGS. 11-12 , the robot  10  may also be outfitted with sensors  60 . The sensors  60  are contained in the gripping devices  20 ,  21  of each gripping mechanism  11 - 14 . The sensors  60  are used to determine conductive or high permittivity defects in an insulator, such as composite/polymer insulators. The sensor and camera electronics  61  are added to the robot  10  as a payload. This approach can adapt to any insulator shed/sheath spacing and diameter and can work on various types of insulators, including composite type insulators. 
     Referring to  FIG. 13 , in another embodiment, a robot  100  may include tracks  101  for driving the robot  100  along an insulator. 
     The foregoing has described an apparatus and method for inspecting high voltage insulators. 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.