Patent Document

BACKGROUND OF THE INVENTION 
       [0001]    This invention relates generally to tools for repair and maintenance of electrical distribution and transmission components, and more particularly to devices for testing insulating poles such as utility line poles and/or “hotsticks”. 
         [0002]    Utility line poles are known for use in repair or maintenance of high-voltage electrical conductors (e.g. overhead transmission lines). The poles are made of an insulating material and are commonly referred to as “hot sticks”. 
         [0003]    The accessibility of electrical power distribution lines varies substantially because the lines are installed both above ground at various elevations and below ground in underground electric power distribution systems. As a result of such a highly diverse and non-uniform manner in which the electrical power distribution lines are positioned and mounted, the access distances between the electrical power distribution lines and the user vary substantially. For example, an above ground electrical power distribution line may be 10 feet or more from the user thus requiring a pole of at least 10 feet in length in order to reach the line. On the other hand, a below ground electrical power distribution line may be only 5 feet or less from the user, thus requiring a much shorter pole than would be required for the above ground scenario. In order to be properly prepared under such highly diverse and non-uniform conditions, user have been typically provided telescoping poles (sticks) or a selection of poles of varying lengths in order to properly accomplish various tasks without being required to go back to home-base to obtain a properly sized portable electrical power distribution line pole. 
         [0004]    Utility line poles used by a user are required to be tested at regular intervals to ensure that the poles are free of defects and continue to provide an insulating barrier between the user and the electrical power distribution lines. OSHA/ASTM standards require utility line poles to be certified every two years using a test cage on full length (35 feet) at full voltage, or requires the pole to be tested in segments. ASTM standards further require a wet test with an optional dry test also being used to determine when a pole visibly dry on the surface has moisture and/or other contaminants not visible. These tests are done using a large testing device located at a testing facility. Unfortunately, users located in the field do not have a way to test the utility line poles that they have on the job during the two years between certification. As a result, a utility line pole may be damaged during use without the knowledge of the user and may no longer be suitable for use. 
         [0005]    Accordingly, there is a need for a portable testing apparatus for utility line poles that allows a user to test a utility line pole in the field between certifications. 
       BRIEF SUMMARY OF THE INVENTION 
       [0006]    This need is addressed by the present invention, which provides a portable, battery-powered apparatus configured to quickly allow a user in the field (or the field office) to test a utility line pole prior to use. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0007]    The invention may be best understood by reference to the following description taken in conjunction with the accompanying drawing figures in which: 
           [0008]      FIG. 1  is a front view of a portable testing apparatus; 
           [0009]      FIG. 2  is a top perspective view of the portable testing apparatus of  FIG. 1 ; 
           [0010]      FIG. 3  is another top perspective view of the portable testing apparatus of  FIG. 1 ; 
           [0011]      FIG. 4  shows electronics of the portable testing apparatus of  FIG. 1 ; 
           [0012]      FIG. 5  is a bottom view of the portable testing apparatus of  FIG. 1 ; 
           [0013]      FIG. 6  shows a utility line pole being tested by the portable testing apparatus of  FIG. 1 ; 
           [0014]      FIG. 7  shows a utility line pole being tested by the portable testing apparatus of  FIG. 1 ; 
           [0015]      FIG. 8  is a bottom view of an alternative configuration of the portable testing apparatus of  FIG. 1 ; 
           [0016]      FIG. 9  shows a utility line pole being tested by the portable testing apparatus of  FIG. 8 . 
           [0017]      FIG. 10  is an overall wiring schematic of the portable testing apparatus of  FIG. 1 ; and 
           [0018]      FIG. 11  is a wiring schematic of a control module of the portable testing apparatus of  FIG. 1  interfaced with switches, batteries, a high voltage generator, electrodes, and a visual display. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0019]    Referring to the drawings wherein identical reference numerals denote the same elements throughout the various views,  FIGS. 1-4  illustrate an exemplary portable testing apparatus  10 . The apparatus  10  includes a housing  12 , a chassis  14  configured to support electronics  16  and a battery pack  18  (may be rechargeable), and one or more electrodes  20 . 
         [0020]    The housing  12  includes a handle  22  to allow an individual to carry the apparatus  10  into the field and/or on to a jobsite, a toggle switch  24  is configured to turn the apparatus  10  on/off and to toggle the apparatus  10  between a dry testing mode and a wet testing mode, and a visual display  26  (as shown, the display is a digital display of known types) configured to display data and operational modes to a user. As illustrated in  FIG. 1 , the display  26  shows an example “wet” mode display. By toggling the switch  24  from a right position to a left position, the display  26  can be changed to a “dry” mode display. It should be appreciated that the left and right positions may be reversed. It should also be appreciated that the microamperes scale changes when toggled between wet mode and dry mode and is calibrated accordingly to provide a user with an accurate reading when testing a device under test (DUT). By toggling the switch  24  to a center position, the apparatus  10  may be turned off. Switch  24  automatically causes the apparatus  10  to “zero” when switching between wet and dry modes. 
         [0021]    As shown, the housing includes a front wall  28  (the handle  22 , switch  24 , and display  26  are located on the front wall  28 ), sidewalls  30 , a first end wall  32 , and a second end wall  34  that collectively define an interior volume and/or cavity  42  configured to receive the electronics  16 , battery pack  18 , and a portion of the chassis  14  therein. 
         [0022]    As illustrated in  FIGS. 5-7 , the chassis  14  includes a tunnel and/or channel  36  extending a length of a bottom  38  of the chassis  14 . The tunnel  36  is configured to receive a DUT such as a utility line pole  40  therein for testing (See  FIGS. 6 and 7 ). One or more electrodes  20  are positioned in the tunnel  36  to test the utility line pole  40  by imparting a voltage of 1.2 kV AC into the utility line pole  40 . As shown, the electrodes  20  are formed of V-shaped conductive plates. 
         [0023]    Alternatively,  FIGS. 8-9 , one or more electrodes  20 ′ may be used instead of or in combination with electrodes  20 . As illustrated, electrodes  20 ′ are in the form of a flexible conductive device such as a spring. It should be appreciated that other suitable flexible conductive devices may be used. Electrodes  20 ′ permit the utility line pole  40  to be contacted by the electrodes  20 ′ in more than two locations—as shown, the electrodes  20 ′ provide a continuous contact to approximately half of the circumference of the utility line pole  40 . 
         [0024]    Additionally, by using flexible electrode  20 ′, a safety switch  44  may be employed. Safety switch  44  prevents the apparatus  10  from running a test without a DUT securely placed within the tunnel  36 . More specifically, placing the apparatus  10  into a test mode using switch  24  will not automatically impart a voltage onto the electrodes  20 ′. Instead, after the apparatus has been placed into a test mode using switch  24 , the user places the utility line pole  40  into the tunnel  36  and in contact with the electrodes  20 ′. The user then presses the apparatus  10  against the utility line pole  40  causing the electrodes  20 ′ to flex until they reach a test position. As illustrated, the test position occurs when the electrodes  20 ′ rest against a top wall  46  of the tunnel  36 ; however, it should be appreciated that the test position may occur prior to the electrodes  20 ′ making contact with the top wall  46 . Once the electrodes  20 ′ reach the testing position, the safety switch  44  turns on the electronics  16  to activate testing of the utility line pole  40 . This operation not only provides safety against inadvertent contact with “hot” electrodes, but it also preserves the battery pack  18  since the battery pack  18  will not be providing any power until the safety switch  44  turns on the apparatus  10 . 
         [0025]    Referring now to  FIGS. 10-11 , the electronics  16  include a control module  50  and a high voltage generator  52 . The generator  52  is powered by the battery pack  18  and generates 1.2 kV at 1.2 kHz alternating current (AC) from 12V direct current (DC) supplied by the battery pack  18 . The 1.2 kV generated by the generator  52  is supplied directly to the electrodes  20  and/or  20 ′ to impart the 1.2 kV directly onto the DUT. AC must be used to detect subsurface defects in the utility line pole  40 . 
         [0026]    The control module  50  interfaces with the display  26  (HD1.1, HD1.2, etc.), switches such as switches  24  and  44 , battery pack  18 , and the high voltage generator  52  to control the operation of the apparatus  10 . As illustrated, the module  50  includes a pair of voltage regulators (U 1  and U 2 ), a plurality of resistors (Rx), a plurality of diodes (Dx), and a pair of Zener diodes (D 3  and D 4 ). The Zener diodes D 3 , D 4  are of particular significance because they are used to dump current to ground when excessive leakage current is created by a dead short and/or defects in the utility line pole  40  or when there is too much voltage. Further, the apparatus  10  automatically stops oscillating if it experiences a dead short to protect the generator  52 . 
         [0027]    The control module  50  is programmed to provide scaling for the apparatus  10 . The control module  50  may be programmed using digital and/or analog inputs. ASTM standards require a dry test using 100 kV per foot with no heat or flashover permitted and a wet test using 75 kV per foot with not heat or flashover permitted and a conduction limit around 75 microamps. Such high testing voltages require a stationary power source capable of testing a 35 foot long DUT and a cage for safety. In order for the apparatus  10  to be portable, the apparatus  10  must be able to mimic a full scale test device. 
         [0028]    Since the apparatus  10  is using 1.2 kV to test the utility line pole  40 , the control module  50  must be capable of converting measured test values into corresponding values associated with full scale testing to provide accurate results consistent with a full scale test device. As a result, the control module  50  displays a microampere scale on the display  26  that mimics a full scale testing device. The microampere scale changes when switched between dry testing and wet testing which is done by toggling switch  24 . When a test is being performed by the apparatus  10 , the control module  50  converts the values measured during testing to full scale values and displays them on the display  26 . Scaling may be done through algorithms and/or look-up tables programmed into the control module  50 . 
         [0029]    In use, a user toggles switch  24  to a first test mode, either a dry test mode or a wet test mode, and allows the apparatus  10  to automatically “zero” itself. The zero function of the apparatus is performed five times per second. Because the housing  12  and chassis  14  are grounded, the apparatus  10  is not frequency sensitive and any variation in zero is eliminated. With the mode selected and the apparatus  10  zeroed, the apparatus  10  is positioned over a section of a DUT such that the DUT is positioned in the tunnel  36  and in contact with the electrodes  20  and/or  20 ′. The apparatus  10  may be moved along the DUT after each test to test the entire length of the DUT. 
         [0030]    Once the apparatus  10  is positioned over the DUT, the apparatus  10  is pressed down onto the DUT until a test position is reached. With the test position reached, the apparatus  10  begins conducting a test by imparting 1.2 kV at 1.2 kHz onto the DUT. Measurements are then conducted, i.e., voltage is measured across a known value resistor and current is computed using E=IR relationship. The voltage is measured every 200 microseconds and software of the apparatus  10  reports a digital “counts” or “steps” value (0-4096 counts over the full range). The control module  50  uses algorithms and/or a look-up table using an amps v. volts relationship for the known resistance to scale the output value to a full scale testing output value and displays that output value on the display  26 . 
         [0031]    When a “flashover” occurs the meter displayed on the display  26  will “peg out” to a maximum value. Additionally, when a dead short occurs, the apparatus  10  will stop oscillating. Once the user conducts testing in the first test mode, the user then toggles switch  24  into a second test mode (mode not selected in first test mode) and conducts testing in the same manner as described above. It should be appreciated that dry testing and wet testing are performed using different testing parameters, for example, wet testing requires the DUT to be sprayed with water to look for beads. 
         [0032]    The foregoing has described a utility line pole testing apparatus and method. All of the features disclosed in this specification (including any accompanying claims, abstract and drawings), and/or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations where at least some of such features and/or steps are mutually exclusive. 
         [0033]    Each feature disclosed in this specification (including any accompanying claims, abstract and drawings) may be replaced by alternative features serving the same, equivalent or similar purpose, unless expressly stated otherwise. Thus, unless expressly stated otherwise, each feature disclosed is one example only of a generic series of equivalent or similar features. 
         [0034]    The invention is not restricted to the details of the foregoing embodiment(s). The invention extends any novel one, or any novel combination, of the features disclosed in this specification (including any accompanying claims, abstract and drawings), or to any novel one, or any novel combination, of the steps of any method or process so disclosed.

Technology Category: 5