Abstract:
An elongate probe of at least 2 feet in length for alerting a user to the presence of electrical energy includes an antenna to sense radiated electrical energy and an indicator to alert a user when activated. Circuitry determines when the sensed electrical energy meets a user adjustable threshold and activates the indicator when the sensed electrical energy meets the user adjustable threshold. An adjustor allows for selecting the user adjustable threshold.

Description:
BACKGROUND  
       [0001]     The present invention generally relates to the field of test equipment, and more particularly to an elongate voltage detection pole to sense the presence of an alternating current (AC) signal voltage at a distance.  
         [0002]     Due to problems with maintenance, corrosion or the poaching of electricity supplied by a public utility company, exposed electrical wire may come in contact with conducting surfaces, such as metal utility poles, manhole covers or puddles of water, resulting in electrified “hot spots” in public areas. These hotspots can be harmful, and even fatal, if contacted by a passerby. Additionally, the area of these hotspots can be very irregular and difficult to detect.  
         [0003]     Thus, there is a need for a system and techniques for sensing an electrified metal utility pole or other structure to allow for proper repair before someone is injured. Additionally, there is a need for a system and techniques for allows an alternating current to be sensed at a distance before an individual moves near the electrified element. Moreover, there is a need for a system and techniques which allows a user to adjust the sensitivity of sensing system by having a high sensitivity when searching at a distance and then reducing the sensitivity when moving closer to the electrified structure.  
         [0004]     Additionally, there is a need for a voltage sensing system which is mounted to a utility pole or other structure and provides an indication when the utility pole is electrified.  
       SUMMARY  
       [0005]     In one aspect of the present invention, an elongate probe of at least two feet in length for alerting a user to the presence of electrical energy includes an antenna to sense radiated electrical energy and an indicator to alert a user when activated. Circuitry determines when the sensed electrical energy meets a user adjustable threshold and activates the indicator when the sensed electrical energy meets the user adjustable threshold. An adjustor allows for selecting the user adjustable threshold. 
     
    
       [0006]     A more complete understanding of the present invention, as well as further features and advantages of the invention, will be apparent from the following detailed description and the accompanying drawings.  
       BRIEF DESCRIPTION OF THE DRAWINGS  
       [0007]      FIG. 1  shows a perspective view of a voltage detection pole in accordance with the present invention;  
         [0008]      FIG. 2  shows a cross sectional view of a voltage detection pole in accordance with the present invention;  
         [0009]      FIGS. 3A and 3B  show a schematic diagram of circuitry suitable for use in a voltage detection pole in accordance with the present invention;  
         [0010]      FIG. 4  shows a schematic diagram of circuitry suitable for use in a voltage detection pole in conjunction with the present invention;  
         [0011]      FIG. 5  shows a utility pole mounted system for detecting alternating current in accordance with the present invention; and  
         [0012]      FIG. 6  shows of block diagram of the system of  FIG. 5  in accordance with the present invention. 
     
    
     DETAILED DESCRIPTION  
       [0013]     The following detailed description of preferred embodiments refers to the accompanying drawings which illustrate specific embodiments of the invention. In the discussion that follows, specific systems and techniques for sensing alternating current are disclosed. Other embodiments having different structures and operations for the manufacture of other systems do not depart from the scope of the present invention.  
         [0014]      FIGS. 1 and 2  show respectively a perspective view and a cross sectional view of a voltage detection pole  100  in accordance with the present invention. The voltage detection pole  100  comprises an elongate shaft  102  enclosing an antenna  104 . The antenna  104  operates as a sensing element for sensing changes in an electromagnetic field near the antenna  104 . In a preferred embodiment, the elongate shaft  102  is a non-conductive material, such as polyvinyl chloride (PVC), for example. The elongate shaft  102  may be telescoping or retractable to allow for easy storage and deployment of the antenna  104 . The elongate probe  100  has a length L, as shown in  FIG. 2 .  
         [0015]     A housing portion  106  affixed to the elongate shaft  102  houses processing electronics  108  connected to the antenna  104  for processing the signal received by the antenna  104  and determining if the antenna  104  is near a conductor conducting an AC signal having a sensed amplitude above a user selectable threshold, as described in greater detail below. The housing portion  106  may also comprise an audible buzzer  107  and a visual indicator  110  controlled by the processing electronics  108  for communicating the presence of a sensed alternating current to a user. Batteries  109  may suitably power the processing electronics. A handle  112 , for holding and manipulating the voltage detection pole  100 , is also attached to the housing portion  106 . The handle  112  holds an adjustment element  114  connected to the processing electronics  108  for controlling the user selectable threshold. Alternately, the housing portion  106  may hold the adjustment element  114 .  
         [0016]      FIGS. 3A and 3B  show a schematic diagram of circuitry  300  suitable for use as the processing electronics  108  in accordance with the present invention. Further general details of the operation of circuitry  300  are provided in U.S. Pat. No. 6,828,767, which is incorporated by reference herein in its entirety.  FIG. 4  shows a schematic diagram of an alternate embodiment of circuitry  400  suitable for use as the processing electronics  108  in accordance with the present invention. The circuitry  400  is similar to the circuitry  400  and corresponding elements have been labeled with common element numbers. In the circuitry  400 , a majority of the discrete elements of the circuit  300  are implemented in an application specific integrated circuit (ASIC)  402  of the circuitry  400 . A 10 microfarad decoupling capacitor  406  may be suitably connected between the positive battery terminal  308  and the negative battery terminal  310 . The resistor  312  (R 2 ) may be 120 Mohms.  
         [0017]     The sensitivity of the voltage detection pole  100  is the voltage threshold level at which the voltage detection pole  100  will provide an indication to the user of sensed AC voltage. As described in U.S. Pat. No. 6,828,767, this sensitivity is determined by the value of the resistor  306 . In order to allow the user of the voltage detection pole  100  to select the voltage threshold level, the resistor  306  may suitably comprise a variable resistor controlled by adjustment element  114 , allowing a user to dynamically control the sensitivity of the voltage detection pole  100  by turning a dial. Alternately, the adjustment element  114  may comprise a switch which switches additional resistive elements into or out of a parallel configuration with the resistor  306  to raise or lower the voltage threshold level. By allowing the value to the resistor  306  to be increased to 1.5 Gohms, the voltage threshold level may be lowered to 2 volts RMS or lower. By decreasing the value of the resistor  306  to 150 Mohms, the voltage threshold level may be raised to 16 volts RMS.  
         [0018]     In order to allow a user to safely determine if an AC voltage is present in an area, the voltage detection pole  100  is preferably at least 2 feet in length, more preferably at least 2.5 feet in length, and in particular at least 3 feet in length, to allow the user detect the AC voltage from a distance without approaching the voltage source too closely. A typical prior art device that has a short length may put the user in danger by forcing the user to approach the AC voltage and risk electric shock. The length of the voltage detection pole  100 , and thus the extension of the antenna  104  from the user, allows the user to quickly move the tip of the voltage detection pole  100  around an area with the voltage threshold level set to a low level and determine if there is any AC voltage present. Thus, in addition to keeping the user further away from dangerous voltages, the length of at least 2 feet allows for more efficient testing of an area by increasing the reach of the test and allowing the end of the voltage detection pole  100  to be quickly moved about. Additionally, the length of at least 2 feet allows the user to test areas or structures that are high off the ground. Moreover, the length of at least 2 feet allows a user to extend the voltage detection pole through an open window of a vehicle to test objects near the vehicle.  
         [0019]     If AC voltage is detected, the user may increase the voltage threshold level as needed while continuing the search to further narrow the area having the AC voltage. In other words, a user may adjust the sensitivity of voltage detection pole  100  by controlling the adjustment element  114  to select a high sensitivity when searching at a distance and then reducing the sensitivity when moving closer to the electrified structure to further narrow the search to the specific hot spot.  
         [0020]     In another aspect of the present invention, a voltage sensing system is adapted for attachment a utility pole or other structure and provides an indication when the utility pole is electrified.  FIG. 5  shows a utility pole mounted system  500  for detecting alternating current in accordance with the present invention.  FIG. 6  shows a block diagram of the system  500  in accordance with the present invention. As seen in  FIG. 5 , a utility pole mounted sensor  502  may be mounted to a metal utility or light pole by steel bands  501 . The sensor  502  may comprise an antenna  504  and processing electronics  507 , which operates in similar fashion to the processing electronics described above, with the voltage threshold set to a predetermined level. A battery  510  suitable for use in low temperature environments may be used to power the pole mounted sensor  502 . Alternatively, other power sources such as solar power, AC power and the like may be utilized. The sensor  502  includes an LED  506  and a buzzer  508  controlled by the processing electronics for alerting someone near the pole that the pole is carrying a potentially harmful alternating current.  
         [0021]     The pole mounted sensor  502  may also include an AC generator  512  for testing the sensor  502 . The AC generator  512  may suitably generate an AC signal of 2-30 volts RMS. When the AC generator  512  is operating and producing a signal, the processing electronics  507  will sense a corresponding signal received by the antenna  504  and cause the LED  506  and buzzer  508  to activate. The AC generator may be activated remotely, utilizing a radio frequency (RF) or infrared (IR) signal, by someone holding an testing unit  520  which communicates with the pole mounted sensor  502 . The testing unit  520  comprises a transmitter  522  controlled by a user activated switch  524  and powered by a battery  526 . When a user activates the switch  524 , the transmitter  522  sends a signal to the receiver  514  of the sensor  502 , which in turn, activates the AC generator  512 . Thus, someone responsible for verifying that no hot spots exist may first view the pole mounted sensor  502  to ensure that the sensor  502  is not reporting an electrified pole and the use the testing unit  520  to test the pole mounted sensor  502  to ensure proper operation. Optionally, the AC generator  512  may be packaged separately from the sensor  502 .  
         [0022]     Although specific embodiments have been illustrated and described herein, those of ordinary skill in the art appreciate that any arrangement which is calculated to achieve the same purpose may be substituted for the specific embodiments shown and that the invention has other applications in other environments. This application is intended to cover any adaptations or variations of the present invention. The following claims are in no way intended to limit the scope of the invention to the specific embodiments described herein.