Abstract:
The invention relates to an apparatus for continuously electrolytically coating a wire for a high tension cable for use in overhead transmission lines, wherein the apparatus comprises a bath for an aqueous electrolytic solution containing a precursor for an electro-ceramic coating on a wire, a first air knife cleaning device, an electrification device for electrifying the wire, a plurality of guide members positioned to route the wire from into, through and out of the bath, a cathodic connection positioned in the bath for contacting the aqueous electrolytic solution, and a power source electrically connected to the electrification device and the cathodic connection, said power source capable of providing high voltage and high current to the wire through the electrification device, and through the wire in the bath to the cathode connection via the aqueous electrolytic solution.

Description:
BRIEF DESCRIPTION OF THE DRAWINGS 
       [0001]    The FIGURE illustrates a schematic of an apparatus for coating a wire in a cable according to an embodiment. 
     
    
     DETAILED DESCRIPTION 
       [0002]    As required, detailed embodiments of the present invention are disclosed herein; however, it is to be understood that the disclosed embodiments are merely exemplary of the invention that may be embodied in various and alternative forms. The figures are not necessarily to scale; some features may be exaggerated or minimized to show details of particular components. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a representative basis for teaching one skilled in the art to variously employ the present invention. 
         [0003]    The FIGURE illustrates a schematic of an embodiment of an apparatus  100  for continuously coating a cable or a single wire or strand for a cable, such as a high tension electrical cable. The cable may have wires comprising aluminum or aluminum alloys. The wire  102  runs from a first spool  104  to a second spool  106 . Each spool  104 ,  106  has a central barrel, or center cylindrical section, and may have flanges extending therefrom on either end of the central barrel. The first spool  104  provides a supply of uncoated, bare wire, such as aluminum, useful for example in a high voltage transmission cable, with the bare wire wound on the barrel of the spool  104 . The second spool  106  receives the coated wire with the coated wire would on the barrel of the spool  106 . 
         [0004]    The wire  102  is fed through a bath  108  comprising a container at least partially filled with an aqueous solution comprising a precursor for a ceramic coating on the wire. The container for the bath  108  may be made from a material that is chemically unreactive with the solution. The container for the bath may be electrically conductive to provide a cathode, or may be made from electrically insulating and non-conductive material. 
         [0005]    A first frame  110 , or main frame, is supported above the bath  108 . In one example, the first frame  110  has a lower sub-frame  112 , first and second end supports  114 ,  116 , and an upper frame member  118  or crossbar. The frame  110  may be made from metal tubing, or other materials, and in one example, the frame  110  is electrically conductive. Legs  120  may support the frame  110  on an underlying surface and above the bath  108 . The lower sub-frame  112  may include first and second bars  122 ,  124  that are spaced apart from one another and may be generally parallel to one another. A central bar  126  is positioned between the first and second bars  122 ,  124 . The first and second end supports  114 ,  116  may include a truss or the like. 
         [0006]    The first spool  104  is supported by the upper frame member  118  or the first end support  114  by a stationary shaft  128 . The spool  104  may be removed from the shaft  128  as needed for operation of the apparatus. A fastener may connect with the end of the shaft  128  to retain the spool  104  on the shaft  128  and allow for removal. The shaft  128  is positioned to be generally perpendicular with a section of the wire  102  as it leaves the spool  104 , with the wire leaving the spool generally tangentially according to one example. A bearing assembly  130  is provided within the cylindrical section of the spool  104  and is sized to fit over the shaft  128  while reducing friction of the spool  104  as it rotates about the shaft  128 . 
         [0007]    An electric motor  132  is provided on the upper frame member  118 . The electric motor may be a DC motor. The electric motor has a drive shaft  136 . 
         [0008]    The second spool  106  is supported by the drive shaft  136  of the electric motor  132 . The spool  106  may be removed from the shaft  136  as needed for operation of the apparatus. A fastener may connect with the end of the shaft  136  to retain the spool  106  on the shaft  136  and allow for removal. The motor  132  shaft and the inner diameter of the spool  106  may be keyed or splined such that they rotate together. 
         [0009]    In alternative embodiments, the electric motor  132  may be connected to the first spool  104 , or each spool  104 ,  106  may be provided with an electric motor. 
         [0010]    A second frame  140 , or drop frame, is supported by the main frame  110  and extends away from the main frame  110  such that it may be received within the bath  108 . In one example, as shown, the second frame  140  is connected to the central bar  126 . The second frame  140  is positioned such that it is partially submerged within solution in the bath  108 . The second frame  140  has at least one guide member  142  to guide the wire through the bath  108 . In the example shown, the second frame  140  has first and second members  144  that drop from the first frame  110  with each frame member  144  having a guide member  142  connected to an end region. Each guide member  142  may be a wheel connected to the frame member  144  by a bearing connection, or may be a nonrotating guide member as is known in the art. 
         [0011]    An electrical contact device  146  is supported by the main frame  110 . The electrical contact device is positioned to contact the wire  102  away from or above the bath  108 . The device  146  provides a dry anode connection to electrify the wire, and electrifies the entire length of the wire with a high voltage and a high current. The electrified wire  102  electrochemically reacts with the solution in the bath  108  to form a coating on the wire. 
         [0012]    In one embodiment, the electrical contact device  146  is a dry anode connection providing at least 50 kW per wire. The electrical contact device may provide 50-60 kW to a single strand of wire in an example of the apparatus  100 . In a further embodiment, the device  146  is a mercury switch having a wheel that rotates with the wire  102  as the wire is fed from spool  104  to spool  106 . A mercury switch has a rotating connector with an electrical connection made through a pool of liquid metal molecularly bonded to the contact, which provides a low resistance, stable connection. As the mercury switch rotates, the fluid maintains the electrical connection between the contacts without wear and with low resistance. The mercury switch is able to provide the high voltage and high current needed to electrify the wire  102 . According to one example, the high voltage is a peak voltage at or above 125 Volts, and the high current is a peak current at or above 450 Amperes and may be alternating current, asymmetric alternating current, direct current, or pulsed direct current. In alternative embodiments, a brushed slip ring, an electrified guide that the wire runs over, or other devices  146  may be used. 
         [0013]    A cathode connection  148  is provided within the bath  108 . The cathode connection  148  may be the container for the bath  108  itself if it is electrically conductive, a metal component, i.e. a plate or tube, positioned within the bath and in contact with the anodizing solution, or a salt bridge. The electrical contact device provides a dry electrical connection with the wire, as the solution in the bath is not sufficiently conductive to provide a wet anode connection and a voltage drop would occur. The device  146  and the cathode connection  148  are connected to a power supply  150 . The power supply  150  may be controlled to provide alternating current to the anode and cathode, and may be high frequency such as 200-10,000 kHz; or may provide asymmetric alternating current, for example, with 400-500 Volts at the anode, 40-50 Volts at the cathode, and a square wave form pattern with a frequency of 0.1-40 milliseconds. In other examples, the power supply may provide direct current or pulsed direct current to the anode and cathode. 
         [0014]    In one example, at least one cleaning device  154  may be positioned to interact with and clean the wire  102  before it enters the bath  108 . The cleaning device  154  may be supported by the frame  110 . The cleaning device  154  may be an air knife that forces pressurized air across the wire as the wire is fed past the air knife to remove any debris. The cleaning device  154  may also be a spray system that sprays pressurized fluid, such as deionized water, distilled water, a solvent such as an alcohol solution, or the like across the wire as the wire is fed past the cleaning system to remove any debris or other undesirable material from the surface of the bare wire, such as cutting fluid, etc. In other examples, the bare wire is sufficiently clean such that no cleaning device is needed for use with the apparatus  100 . 
         [0015]    In another example, an air knife  156  or another similar device is positioned to interact with the wire  102  after it exits the bath  108 . The air knife  156  may be supported by the frame  110 . The air knife  156  provides pressurized air across the wire as the wire is fed past the air knife to remove any excess solution on the surface of the coated wire after it exits the bath. A collection system may be adjacent to the air knife  156  to collect the excess solution and return it to the bath  108  in a recycling process. In other examples, an air knife is not used with the apparatus  100  based on a low or negligible amount of solution on the surface of the coated wire. 
         [0016]    One or more sets of guides  158  may be provided on the first frame  110  or the second frame  140  to guide the wire  102  to travel along a predetermined path between the first spool  104  and the second spool  106 . The guides  158  may be roller guides, including one or two plane guides, or the like. The guides  158  may assist in directing the wire to pass by the cleaning device  154  and/or the air knife  156 . The guides  158  may assist in a smooth feed of the wire from the first spool  104 . The guides  158  may also present the wire at the appropriate angle to the second spool  106  for a smooth winding. 
         [0017]    A controller  160  is in communication with the electric motor  132 . The controller  160  may be a single controller or multiple controllers in communication with one another. The controller  160  may be connected to random access memory or another data storage system. In some embodiments, the controller  160  has a user interface. The controller  160  is configured to control the electric motor  132 , the power supply  150 , and the cooling system  152  for startup procedures, shut down procedures, and emergency stop procedures. 
         [0018]    In one embodiment, the controller  160  is in communication with a first sensor  162  and a second sensor  164 . The first and second sensors  162 ,  164  are used with the first and second spools  104 ,  106 , respectively. The first and second sensors  162 ,  164  may be position sensors for wire tracking. 
         [0019]    The controller  160  controls the speed of the electric motor  132  to control the speed of the second spool  106  and the feed speed of the wire through the apparatus. By controlling the feed speed of the wire  102 , the residence time of the wire within the bath  108  is controlled. In one embodiment, the controller  160  controls the motor  132  speed to maintain a residence time within a predetermined range or at a predetermined speed. In one example, the residence time is approximately five to ten seconds and/or the feed speed is 100 feet per minute. As the amount of wire on the first spool  104  (and the diameter of the wrap of wire) decreases, the spool must spin faster to provide the same feed rate of wire through the bath. Likewise, as the amount of wire on the second spool  106  (and the diameter of the wrap of wire) increases, the spool  106  must spin slower to provide the same feed rate of wire through the bath. 
         [0020]    As the apparatus  100  is operated, bare wire leaves the spool  104  and travels over the electrical contact device  146  and is electrified with a high current and a high voltage via a dry anode connection. The wire may be an aluminum or aluminum alloy wire in an embodiment. The bare wire then enters the bath  108 . In one example, the bath contains an aqueous electrolytic solution containing at least one of a complex fluoride and an oxyfluoride. In other examples, other solutions as disclosed herein may be used. The wire electrochemically reacts with the precursor in the bath by passing a current between the wire in the bath and a cathode in the bath to form the coating. This reaction forms a visible light-emitting discharge adjacent to the wire (or an oxygen plasma) and a hydrogen gas from the water in the aqueous solution. The electrified wire may form a plasma with the liquid precursor, with the bath acting as a cathode and the wire acting as an anode. A coating is formed on the bare wire, and the coating may be a metal/metalloid oxide electro-ceramic. The coating has an emissivity greater than that of the bare wire. The thickness of the coating is controlled via the residence time of the wire within the bath. 
         [0021]    The continuous length of the wire  102  may be electrified, as the wire is made of a highly conductive material and designated for use in electrical cable. As such, the first spool  104 , the frame  110 , and various guides or devices on the frame  110  may also be electrified. The wire acts as an anode in the bath  108 . 
         [0022]    The second spool of coated wire  102  may be removed from the apparatus  100  and used to form a high voltage transmission or distribution cable. Multiple spools of coated wire may be combined or bundled to form a cable. Additionally, bare wire and/or support wires may be added to the cable assembly. In one example, bare wires and support wires are internal wires in the cable, and the coated wires form the outer perimeter wires of the cable. The various wires of the cable may be tensioned to provide a predetermined degree of twist. The cable may be installed on a tower or in the electrical grid for use transmitted high voltage electrical power, and as such the outer coated surface of the cable formed by the coated wires interacts with the environment to cool the cable by emitting radiation, including radiation in the infrared wavelength. 
         [0023]    While exemplary embodiments are described above, it is not intended that these embodiments describe all possible forms of the invention. Rather, the words used in the specification are words of description rather than limitation, and it is understood that various changes may be made without departing from the spirit and scope of the invention. Additionally, the features of various implementing embodiments may be combined to form further embodiments of the invention.