Abstract:
Disclosed is an apparatus for cable inspection, which inspects an aerial cable used in electric power transmission, the apparatus including: first and second plates spaced apart from each other; a lower clamp disposed on the first plate; an upper clamp disposed on the second plate to face the lower clamp and having a through hole in a vertical direction; a distance adjustment unit configured to adjust a separation distance between the first and second plates; an indenter indented in a coating of the cable through the through hole; a first load cell configured to measure an indentation force of the indenter and to output a signal corresponding to the measured indentation force; a second load cell disposed under the lower clamp and configured to measure pressure applied to the cable and to output a signal corresponding to the measured pressure; and an indenter moving unit configured to control movement of the indenter. According to the present invention, deterioration of a cable is measured using a plurality of sensors so that measurement accuracy can be improved and measurement of deterioration of the cable can be performed in a state in which the cable is disposed.

Description:
CROSS-REFERENCE TO RELATED PATENT APPLICATION 
       [0001]    This application claims the benefit of Korean Patent Application No. 10-2015-0129615, filed on Sep. 14, 2015, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein in its entirety by reference. 
       BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The present invention relates to an apparatus for cable inspection, and more particularly, to an apparatus for cable inspection, which is capable of inspecting an aerial cable in a state in which the aerial cable is disposed. 
         [0004]    2. Description of the Related Art 
         [0005]    As industries have been developed today, the use of power increases gradually. In addition, facilities are established on a large scale and require high reliability. Thus, stabilization of electric facilities are needed. In particular, high reliability of the supply of electricity may be an essential element for an industrial society. 
         [0006]    A cable for supplying power may be classified into an aerial cable and an underground cable. The aerial cable is an electric wire fixed to an insulator installed at a steel tower or telegraph pole. Because the aerial cable is installed at a high position, when an accident occurs, it takes long time to do restoration and thus, accident prevention is preferable. 
         [0007]    Thus, it is required that a state of a cable is measured and management of the cable is performed according to the measured state so as to prevent an accident. 
         [0008]    A cable exposed to the outside, like the aerial cable, may be deteriorated due to the effect of sun light, etc. In order to check the deterioration state of the cable, part of the installed cable is collected as a sample and is moved to a laboratory and then, deterioration inspection should be carried out. However, sample collecting of the cable inevitably results in damage of the cable. 
         [0009]    In addition, a conventional cable indentation testing machine has a structure in which an indentation testing motor operates to apply indentation to a coating of a cable, to measure indentation using one load cell and when an indentation force is equal to or greater than a predetermined indentation force, the indentation testing motor moves backward. Because a single load cell is used in the conventional cable indentation testing machine, the degree of precision is low. 
         [0010]    In addition, the conventional cable indentation testing machine has the problem that a cable to be measured is not accurately fixed using a mechanical torque switch, etc. whenever measurement is performed. 
         [0011]    In addition, the conventional testing machine has the problem that an error in force measurement occurs due to a change in friction of a driving unit caused by alignment defects during a cable tightening/releasing operation, bending of an indenter caused by repetitive use, etc. 
         [0012]    Korean Patent Laid-open Publication No. 2005-100241 may be exemplified as the prior art relating to the present invention. 
       SUMMARY OF THE INVENTION 
       [0013]    The present invention provides an apparatus for cable inspection, which measures deterioration of a cable using a plurality of load cells so that measurement accuracy can be improved. 
         [0014]    The present invention also provides an apparatus for cable inspection, which is capable of measurement of deterioration of a cable in a state in which the cable is disposed. 
         [0015]    The present invention also provides an apparatus for cable inspection, which induces an accurate close contact by causing fine vibration so that, when a cable is mounted on a clamp, the cable is accurately in close contact with the clamp. 
         [0016]    According to an aspect of the present invention, there is provided an apparatus for cable inspection, which inspects an aerial cable used in electric power transmission, the apparatus including: first and second plates spaced apart from each other; a lower clamp disposed on the first plate; an upper clamp disposed on the second plate to face the lower clamp and having a through hole in a vertical direction; a distance adjustment unit configured to adjust a separation distance between the first and second plates; an indenter indented in a coating of the cable through the through hole; a first load cell configured to measure an indentation force of the indenter and to output a signal corresponding to the measured indentation force; a second load cell disposed under the lower clamp and configured to measure pressure applied to the cable and to output a signal corresponding to the measured pressure; and an indenter moving unit configured to control movement of the indenter. 
         [0017]    The apparatus may further include a vibrator connected to the lower clamp and configured to apply vibration to the lower clamp. 
         [0018]    The apparatus may further include an LM guide disposed between the lower clamp and the second load cell. 
         [0019]    Facing surfaces of the upper clamp and the lower clamp may be concavely formed. 
         [0020]    The distance adjustment unit may include: a pair of screw bolts configured to connect both ends of the first plate and both ends of the second plate, respectively; a first support load having one end connected to one end of the first plate, the first support load being connected in parallel with the screw bolts; a first motor disposed on one end of the first support load and having a rotational shaft connected to one of the pair of screw bolts; pulleys disposed on one end of each of the pair of screw bolts; and a belt configured to connect the pulleys so as to deliver a rotational force of the first motor to the screw bolt that is not connected to the first motor; 
         [0021]    Nuts may be disposed on both ends of each of the first and second plates and are connected to the screw bolts. 
         [0022]    The indenter moving unit may include: a second support load disposed on one side of the upper clamp; a second motor fixed to one end of the second support load; a stem nut disposed on a rotational shaft of the second motor; and a bolt having one end connected to an upper portion of the first load cell and the other end coupled to the stem nut and moving in a vertical direction. 
         [0023]    The first motor and the second motor may be stepping motors. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0024]    The above and other features and advantages of the present invention will become more apparent by describing in detail exemplary embodiments thereof with reference to the attached drawings in which: 
           [0025]      FIG. 1  is a view of an example of a configuration of an apparatus for cable inspection according to an embodiment of the present invention; and 
           [0026]      FIGS. 2 and 3  are views illustrating an operating state of the apparatus for cable inspection according to an embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0027]    The present invention will now be described more fully with reference to the accompanying drawings, in which exemplary embodiments of the invention are shown. 
         [0028]      FIG. 1  is a view of an example of a configuration of an apparatus for cable inspection according to an embodiment of the present invention. 
         [0029]    Referring to  FIG. 1 , an apparatus  100  for cable inspection according to an embodiment of the present invention includes first and second plates  110 A and  110 B, a lower clamp  120 A, an upper clamp  120 B, a distance adjustment unit  130 , an indenter  150 , a first load cell  160 A, a second load cell  160 B, and an indenter moving unit  170 . 
         [0030]    The first and second plates  110 A and  110 B each have a rectangular shape having a predetermined size and are spaced apart from each other. A separation distance between the first and second plates  110 A and  110 B may be adjusted by the distance adjustment unit  130  that will be described below. 
         [0031]    Elements to be described below are connected to the first and second plates  110 A and  110 B. 
         [0032]    Nut structures are formed on both ends of each of the first and second plates  110 A and  110 B so that connection of screw bolts  134  that will be described below can be easily performed. 
         [0033]    The lower clamp  120 A is disposed on the first plate  110 A. The lower clamp  120 A may fix a cable  1  to be inspected, together with the upper clamp  120 B that will be described below. 
         [0034]    The upper clamp  120 B is disposed on the second plate  110 B and faces the lower clamp  120 A. 
         [0035]    When the cable  1  to be inspected is disposed between the upper clamp  120 B and the lower clamp  120 A, the upper clamp  120 B may fix the cable  1  by reducing a separation distance between the upper clamp  120 B and the lower clamp  120 A and may maintain a fixed state. 
         [0036]    Here, preferably, the lower clamp  120 A and the upper clamp  120 B are formed in such a way that their facing surfaces are concavely formed and thus fixing of the cable  1  and maintaining of the fixed state can be easily performed. 
         [0037]    Preferably, a through hole  126  is formed in the center of the upper clamp  120 B in a vertical direction so that the indenter  150  that will be described below may pass through the through hole  126 . 
         [0038]    Meanwhile, the second load cell  160 B that will be described below is disposed under the lower clamp  120 A, and a vibrator  122  is connected to one side of the lower clamp  120 A. 
         [0039]    The vibrator  122  applies predetermined vibration to the lower clamp  120 A when the cable  1  to be inspected is disposed between the upper clamp  120 B and the lower clamp  120 A. That is, when the cable  1  is disposed between the upper clamp  120 B and the lower clamp  120 A, the cable  1  may deviate from the center of the clamp. In this case, the vibrator  122  applies vibration to the lower clamp  120 A, and the lower clamp  120 A vibrates in a horizontal direction, and the cable  1  that deviates from the center of the clamp may be disposed in the center of the clamp. 
         [0040]    Here, an LM guide  124  may be disposed between the lower clamp  120 A and the second load cell  160 B that will be described below so that horizontal vibration of the lower clamp  120 A can be easily performed. 
         [0041]    The LM guide  124  is disposed in parallel with a vibration-applying direction of the vibrator  122  so that, when vibration is applied to the lower clamp  120 A, vibration of the lower clamp  120 A can be easily performed. 
         [0042]    The distance adjustment unit  130  adjusts the separation distance between the first and second plates  110 A and  110 B. By adjusting the separation distance between the first and second plates  110 A and  110 B, fixing of the cable  1  may be performed between the lower clamp  120 A and the upper clamp  120 B. 
         [0043]    The distance adjustment unit  130  includes a pair of screw bolts  134 , a first support load  132 , a first motor M 1 , pulleys  136 , and a belt  138 . 
         [0044]    The pair of screw bolts  134  are rotated in line with each other so that the separation distance between the first and second plates  110 A and  110 B may be changed. 
         [0045]    One end of each of the pair of screw bolts  134  is connected to both ends of the first plate  110 A, and the other end of each of the pair of screw bolts  134  is connected to both ends of the second plate  110 B. Here, the pair of screw bolts  134  are disposed in parallel. 
         [0046]    Preferably, nuts are disposed on both ends of each of the first plate  110 A and the second plate  110 B so that connection of the screw bolts  134  can be easily performed. 
         [0047]    The first support load  132  is disposed on one end of the first plate  110 A perpendicularly to the first plate  110 A. In this case, the first support load  132  is disposed in parallel with the screw bolts  134 , and a first motor M 1  that will be described below is disposed on the first support load  132 . 
         [0048]    The first motor M 1  is disposed on one end of the first support load  132 , and a rotational shaft of the first motor M 1  is connected to one end of one of the pair of screw bolts  134 . 
         [0049]    Pulleys  136  are connected to the other end of each of the pair of screw bolts  134 . The pulleys  136  are connected to each other via a belt  138 . Thus, when the first motor M 1  operates, the screw bolt  134  to which the first motor M 1  is connected, is rotated, and a rotational force thereof is delivered to the opposite screw bolt  134  via the belt  138  so that the pair of screw bolts  134  may be rotated in line with each other. 
         [0050]    Thus, when the pair of screw bolts  134  are rotated in line with each other due to the operation of the first motor M 1 , the second plate  110 B connected to the screw bolt  134  is moved in the vertical direction so that the separation distance between the first and second plates  110 A and  110 B may be adjusted. 
         [0051]    The indenter  150  is moved by the first motor M 1  that will be described below in the vertical direction and is indented in the cable  1 . The indenter  150  has a shape of a load having a predetermined diameter and a predetermined length. 
         [0052]    The indenter  150  is indented in the cable  1  through the through hole  126  on the upper clamp  120 B. Moving of the indenter  150  will be described below. 
         [0053]    The indenter  150  is a well-known technology in the art and thus, detailed descriptions thereof will be omitted. 
         [0054]    The first load cell  160 A measures pressure applied when the indenter  150  is indented in the cable  1 , measures pressure when the indenter  150  is indented in the cable  1 , and outputs a signal corresponding to the measured pressure. 
         [0055]    The indenter  150  that will be described below is disposed under the first load cell  160 A. Preferably, the first load cell  160 A is not rotated around a central axis but is moved only in the vertical direction. 
         [0056]    The second load cell  160 B is disposed on the first plate  110 A, and the lower clamp  120 A is disposed above the second load cell  160 B. The second load cell  160 B measures pressure applied to the lower clamp  120 A and outputs a signal corresponding to the measured pressure. Here, because the cable  1  is disposed on the lower clamp  120 A, pressure applied to the lower clamp  120 A is the same as pressure applied to the cable  1 . 
         [0057]    A configuration for moving the indenter  150  will now be described. 
         [0058]    The indenter moving unit  170  is disposed to move the indenter  150 . 
         [0059]    The indenter moving unit  170  moves the indenter  150  in the vertical direction so that the indenter  150  may be indented in the cable  1 . 
         [0060]    The indenter moving unit  170  includes the second support load  174 , a second motor M 2 , a stem nut  171 , and a bolt  172 . 
         [0061]    The second support load  174  is a load having a predetermined length and is disposed on one side of the upper clamp  120 B. 
         [0062]    The second motor M 2  is fixedly disposed on a top end of the second support load  174 . 
         [0063]    The first motor M 1  and the second motor M 2  are stepping motors. 
         [0064]    The stem nut  171  is connected to a rotational shaft of the second motor M 2 . 
         [0065]    The bolt  172  has a predetermined length. The bolt  172  is disposed on upper portion of the first load cell  160 A. The bolt  172  is disposed in parallel with a movement direction of the indenter  150 . The bolt  172  is connected to the stem nut  171  and is moved in the vertical direction according to rotation of the stem nut  171 . 
         [0066]    The bolt  172  having a predetermined length is connected to the stem nut  171 . The second load cell  160 B that will be described below is connected to a bottom end of the bolt  172 , and the indenter  150  is connected to a lower portion of the second load cell  160 B. 
         [0067]    Thus, when the second motor M 2  is rotated in a predetermined direction, a rotational force thereof is delivered to the second load cell  160 B that will be described below via the stem nut  171  and the bolt  172  so that the second load cell  160 B may be moved in the vertical direction. Because the indenter  150  is connected to a lower portion of the first load cell  160 A, the indenter  150  may be indented in the cable  1  in the vertical direction. 
         [0068]    The use of the present invention will now be described. 
         [0069]      FIGS. 2 and 3  are views illustrating an operating state of the apparatus  100  for cable inspection according to an embodiment of the present invention. 
         [0070]    A user carries the apparatus  100  for cable inspection according to the present invention into a position where a cable to be inspected, i.e., an aerial cable is disposed. 
         [0071]    Referring to  FIG. 2 , the user allows the lower clamp  120 A and the upper clamp  120 B to be spaced apart from each other by a predetermined separation distance so that the cable  1  may be disposed between the lower clamp  120 A and the upper clamp  120 B. The separation distance in this case is larger than a diameter of the cable  1 . The user disposes the cable  1  between the lower clamp  120 A and the upper clamp  120 B. 
         [0072]    Referring to  FIG. 3 , the user operates the first motor M 1  so that the second plate  110 B may be moved in a downward direction. Due to the movement of the second plate  110 B, the lower clamp  120 A and the upper clamp  120 B are in close contact with lower and upper portions of the cable  1  so that the cable  1  may be fixed between the lower clamp  120 A and the upper clamp  120 B. 
         [0073]    When the lower clamp  120 A and the upper clamp  120 B are in contact with the lower and upper portions of the cable  1 , the vibrator  122  operates so that the clamp and the cable  1  may be in close contact with each other. 
         [0074]    Subsequently, the user operates the second motor M 2  so that the indenter  150  may be indented in the cable  1 , as illustrated in  FIG. 1 . 
         [0075]    The user stores signals output from the first load cell  160 A and the second load cell  160 B in a predetermined storage unit and measures the degree of deterioration of the cable  1  using data output simultaneously with the signals. 
         [0076]    According to the present invention, deterioration of a cable is measured using a plurality of sensors so that measurement accuracy can be improved and measurement of deterioration of the cable can be performed in a state in which the cable is disposed. 
         [0077]    As described above, according to the present invention, deterioration of a cable is measured using a plurality of sensors so that measurement accuracy can be improved. 
         [0078]    In addition, according to the present invention, measurement of deterioration of the cable can be performed in a state in which the cable is disposed. 
         [0079]    Furthermore, according to the present invention, fine vibration occurs to induce an accurate close contact so that, when the cable is mounted on a clamp, the cable can be accurately in close contact with the clamp. 
         [0080]    While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it will be understood by those of ordinary skill in the art that various changes in form and details may be made therein without departing from the spirit and scope of the present invention as defined by the following claims.