Abstract:
An underground utility vault inspection system and method includes a pre-defined railway installed in an underground utility vault, and an inspection vehicle adapted to traverse the railway to provide inspection results to inspection personnel. The inspection vehicle includes inspection tools for inspecting underground power lines and equipment, recording inspection results, and transmitting the inspection results to the inspection personnel.

Description:
This application claims the benefit of Provisional Application No. 61/476,923 filed on Apr. 19, 2011. 
    
    
     BACKGROUND OF THE INVENTION 
     The present invention relates generally to an inspection system and method for underground power line inspection. 
     Underground power lines require inspection and maintenance to ensure long-term performance and reliable operations. Inspection and maintenance access is typically obtained through vaults (manholes) or tunnels,  FIGS. 1-5 , through which the lines run. Conventional inspection practices often involve human entry to the vault or tunnel and require utility personnel to have direct access to the line components for visual inspection and/or necessary measurements using portable instruments,  FIGS. 6 and 7 . However, certain sections of the underground lines may be difficult to access or there may be restrictions to get access which may require taking the entire circuit out of service and/or entail significant personnel safety hazards. Examples include components in underground splice vaults where the space is confined with potential hazards. 
     Entering a confined space with potential hazards is restricted by many electric utilities. As a result, inspection personnel cannot easily or safely access certain sections of underground power lines. In many occasions, getting access to those sections or areas is costly. For example, line outages are required by many utilities for personnel to enter an underground vault for inspection. In some instances, inspection for these areas may be performed with the assistance of extension sticks or moving carts. However, such inspection methods can be limited and difficult to standardize. 
     Under a limited scope, inspection may also be performed using remote sensing. In this sensing technology, sensors are fixed at specific locations adjacent to or near the components to be inspected. The measurements are then made, and data retrieved and processed on site or transferred to a remote location. However, because remote sensing devices, if used, are fixed at specific locations within the vaults, they may not have full view of all components, thereby limiting the effectiveness of the inspection. 
     Accordingly, there is a need for an underground power line vault inspection system and method that allows complete inspection of an underground power line without compromising personnel safety or performing a costly line outage. 
     BRIEF SUMMARY OF THE INVENTION 
     These and other shortcomings of the prior art are addressed by the present invention, which provides a system and method for the inspection of underground power lines running through a vault or tunnel. 
     According to one aspect of the invention, an underground utility vault inspection system includes a pre-defined railway installed in an underground utility vault; and an inspection vehicle adapted to traverse the railway to provide inspection results to inspection personnel. The inspection vehicle includes inspection tools for inspecting underground power lines and equipment, recording inspection results, and transmitting the inspection results to the inspection personnel. 
     According to another aspect of the invention, a method for inspecting underground utility vaults includes the steps of providing an inspection vehicle adapted to traverse a railway disposed in an underground utility vault; moving the inspection vehicle to a pre-determined location in the utility vault; and using the inspection vehicle to inspect utilities located in the utility vault. 
    
    
     
       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: 
         FIGS. 1 and 2  show an entrance to an underground power line vault; 
         FIGS. 3-5  show an inside of an underground power line vault; 
         FIGS. 6 and 7  show individuals performing visual inspection of underground power lines; 
         FIG. 8  shows an inspection system according to an embodiment of the invention; 
         FIG. 9  shows the inspection system of  FIG. 8  with a manipulator arm to perform inspection of an underground power line; and 
         FIGS. 10-14  show rail system layouts for the system of  FIG. 8 . 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring to the drawings, an exemplary underground utility vault inspection system and method according to an embodiment of the invention is illustrated in  FIGS. 8 and 9  and shown generally at reference numeral  10 . The system  10  includes a robotic inspection vehicle  11  mounted on a railway  12  for movement through an underground vault  13  to provide inspection of utilities such as underground power lines running therethrough and any other equipment contained therein. 
     The vehicle  11  uses various sensors, cameras, and instruments to conduct the inspection. For example, the vehicle  11  may be equipped with optical image sensors, infrared temperature sensors, radio frequency interference sensors, acoustic sensors, hazard gas detectors, and corrosion sensors to perform visual inspection, thermal inspection, gas monitoring, and arcing detection. For optical image sensing or visual inspection, lighting may be provided on the device to assist the inspection. The area coverage of the inspection can be preprogrammed, controlled by image/object recognition, or manually controlled by the operator aboveground through real-time image monitoring. The inspection device may also be used to collect data from locally fixed sensors or data loggers (i.e., inside the vault or tunnel) as it passes by these devices. The inspection information can be processed in real-time by the inspection device itself or in a post analysis by other processing equipment. 
     The vehicle  11  may also be fitted with a manipulator arm  14 ,  FIG. 9 , to conduct more detailed inspections by maximizing coverage or to clean a surface of the underground power line. The manipulator arm  14  may also be used to conduct repairs such as coating repair, ground wire tightening, and link box cleaning. As shown, the manipulator arm  14  may be formed in sections  16 - 18  to allow the arm  14  to extend to a desired length or to allow the arm  14  to be articulated into tight areas by manipulating each of the sections  16 - 18  individually. 
     The vehicle  11 , sensors, cameras, and instruments may be remotely controlled by wireless or wired technologies, wherein the wireless or wired technology operates in conjunction with or independent of the railway  12 . The vehicle  11  may be powered through a battery system or a wired power supply, wherein the wired supply may or may not utilize the railway  12 , or by indirect power transfer as an inductive pickup. The vehicle may be retrieved by the operator by backing off from the same railway or through a return railway. 
     The vehicle  11  may be permanently installed on the railway  12  to perform routine and scheduled inspections or used as a portable device to inspect components where a permanent, temporary, or retrofit railway is installed. Thus, one vehicle  11  may be used for multiple locations. The vehicle  11  may be universal for inspection of various types of vaults, tunnels, or inspections or it may be specifically designed for a specific type of inspection. 
     The vehicle  11  is custom fitted to travel on the railway  12 . The vehicle  11  may move along the line of the railway  12  in a linear mode (i.e., parallel to the track) or in a circular motion around the axis of the railway  12  (i.e., executing a circle whose radius is perpendicular to the track). The railway  12  itself may incorporate inventive features to permit rotational as well as linear movement of the vehicle. For example, the railway  12  may have sections that are adapted to rotate (i.e., around its own axis) when the vehicle  11  enters the section. Alternatively, the railway  12  may contain embedded circumferential grooves or axial spines that guide and/or enable the vehicle  12  to accomplish a circular motion. The vehicle  11  may itself have the capability to swivel, turn, extend, telescope, or move in any suitable direction. 
     The railway  12  may be portable or permanently installed in underground or confined spaces so that the vehicle  11  can travel through a preprogrammed path for the inspection. The railway  12  may be a solid and fixed rail system, a flexible wire system, or a controllable flexible path that has the capability to reach a specific location. The railway  12  may consist of any number of tracks or rails, and may have switches to direct vehicle  11  travel along different routes. The railway  12  may be made of any suitable material capable of supporting the vehicle  11  to allow the vehicle  11  to carry out its intended function. The railway  12  may be specially designed and installed in new/existing vaults or tunnels, an existing system, or a retrofit to an existing structure. 
     As shown in  FIGS. 10-14 , the railway  12  may also be configured in any shape or profile and traverse multiple directions to allow proper inspection. For example, the railway  12  may be configured in a vertical plane configuration,  FIG. 10 , a horizontal plane configuration,  FIG. 11 , a specialized path configuration,  FIGS. 12 and 13 , a moveable rail configuration,  FIG. 14 , or any combination of the above to allow the vehicle to properly inspect underground power lines. 
     The railway  12  may also incorporate a means to power the vehicle  11 . For example, the railway could include a low voltage conductor embedded in the railway  12  that provides power to an inductively coupled power pickup device on the vehicle  11 . The railway  12  could also receive power from state of the art power harvesting devices inside the vault or tunnel, or from local power sources (e.g., a battery pack) and distribute that power to the vehicle  11 . The railway  12  may also incorporate components of a power harvesting scheme, such as integrally providing an inductive loop or pickup for harvesting power from cable sheath currents. The railway  12  may similarly incorporate a means of routing control signals to the vehicle  11  and/or means to transmit information back to the operator. For example, the railway  12  may be used to obtain the distance, speed, and stops that the vehicle  11  travels using suitable fixed sensors or RFI devices along the track. The terminus of the railway  12  that is near the aboveground access port could also be fitted with a low power transmitter/receiver, for example, to permit easy “drive-by” communications by suitably equipped utility vehicles, or for low-power wireless mesh transmissions to nearby transmitter/receivers. 
     Once the railway  12  is installed in the underground vault or tunnel, the vehicle  11  is attached to the railway  12  and positioned for operation. The vehicle  11  may be pre-programmed to traverse a specific path along the railway  12  or may be controlled by wire or wirelessly to traverse the railway  12  as desired. As the vehicle  11  traverses the railway  12 , the vehicle uses its many sensors and arm  14  to inspect the underground power lines. The vehicle  11  may be used to perform an inspection for a specific problem or problems or may be used to perform an overall inspection of the health of the underground power line. 
     The foregoing has described an underground utility vault inspection system and method. 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.