Patent Publication Number: US-2023163579-A1

Title: Live Conductor Stringing, Maintenance and Repair Method

Description:
FIELD OF THE INVENTION 
     The present invention relates generally to high voltage power transfer systems. In particular, the present invention relates to replacing conductors in a high voltage power transfer system. 
     BACKGROUND OF THE INVENTION 
     Users of large amounts of electrical power such as cities, manufacturing facilities, and other high-power users are often located quite a distance away from sources of electrical power such as hydroelectric dams and power plants. In order to deliver large amounts of power from the source of generation to the power consumers, large, high-capacity, high-voltage power lines are used. 
     Typically, alternating current (“AC”) is generated in a three-phase configuration. For the purposes of this document, the three phases will be referred to as A, B and C phase. A phase, B phase and C phase are all transported over separate conductors. In some instances direct current (DC power) is used in which case two conductors are used and are referred to as A and C phase. Typically, the conductors are comprised of long wires supported on large support structures such as towers or power poles. The separate A, B and C phase conductors are typically attached to the same support structures on insulators. 
     From time to time, the power lines transporting the power may require maintenance. For example, a section of the conductor may need to be replaced, an insulator insulating the power line from the support structure may need to be replaced, or, the support structure itself may need repair or replacement. In some cases, conductors may be functioning properly, but need to be replaced by higher-capacity conductors in order to transport more power. 
     Typical maintenance on power lines requires that the power be shut off before the line can be worked on. High induction currents may be induced into a conductor located in the proximity of other high voltage conductors, thus creating a hazard in order to work on a particular conductor. 
     Shutting off the power creates a disruption of power delivery to customers. A power user may be forced to do without power during the time the power line is maintained, which is undesirable for a variety of reasons. To provide consumers power while a particular line is being worked on, the load may be shifted to other power lines to deliver the power to the end user. Unfortunately, shifting power to other transmission lines is not always possible because redundant systems may not exist, or transmission lines may already be operating at or near capacity level and not able to deliver the required power. 
     Previously, the applicant developed methods for conducting maintenance work on energized high voltage conductors in electrical transmission systems, such as the methods described in the U.S. Pat. No. 7,535,132 issued on May 19, 2009 to Quanta Associates, L. P. One of the methods taught in U.S. Pat. No. 7,535,132 involves moving each of the conductors needing replacement to a temporary position, stringing new conductors in or near the originating positions of the old conductors, transferring the power load from each of the old conductors to each of the new conductors using transfer buses, and removing the old conductors. 
     However, one problem that often occurs during the execution of the methods described in U.S. Pat. No. 7,535,132 is that the movement of each of the old conductors requiring replacement to temporary positions at the same time will often result in the transposition of the conductors carrying phases A, B and C, whereby, for example, if the phases were originally arranged in the relative horizontal positions of A— B— C prior to moving the phases to their temporary positions, the relative horizontal positions may often end up in the positions B— A— C after the movement has occurred. Furthermore, in order to achieve moving all three phases to temporary positions at the same time using the methods described in U.S. Pat. No. 7,535,132, it is often necessary to utilize long jumper cables to connect the temporarily relocated section of conductor to the remaining sections, which jumper cables for one phase must necessarily cross over the conductors of another phase while carrying a power load, as illustrated in  FIG.  35    of U.S. Pat. No. 7,535,132. These are examples of what the Applicant refers to as illegal transpositions of the phase conductors. The disclosure of U.S. Pat. No. 7,535,132 is incorporated herein in its entirety, and is hereinafter referred to as the &#39;132 patent. 
     Both scenarios described above results in the transposition of the phase conductors, leading to an imbalance in the impedances of the phase conductors and therefore, fluctuations in the voltage and current carried on the phase conductors. Such fluctuations, if large enough, will cause the protective relays to trip the breakers, causing a disruption in the delivery of power on the transmission lines being worked upon. To avoid this result, the owner of the power transmission line may choose to disable the safety relays while a live reconductoring project is underway. However, disabling the safety relays results in a risk that a sudden fluctuation in the voltage and current during the live reconductoring project may damage the transmission network. 
     Accordingly, it is desirable to provide an improved method to allow high voltage power transmission lines to be worked on, replaced or maintained without requiring power to stop being delivered or diverted over to other remote transmission lines, and without resulting in the illegal transposition of the phase conductors that could lead to faults in the transmission line. 
     SUMMARY 
     One example embodiment of the present invention provides a method for maintaining a section of an electrified, three-phase power conductor line, wherein the three phases are in a common plane, in an ordered sequence and strung between a set of support structures, wherein at least two equal potential zones are employed in communication with at least one of said three phases, the method comprising steps of:
     a) positioning at least one auxiliary support substantially adjacent the set of support structures so as to support an electrified section of a first phase-needing-maintenance,   b) moving said section of said first phase-needing-maintenance so as to be strung upon said at least one auxiliary support and said at least two auxiliary dead end supports, wherein said first and second dead end junctures are supported by said at least two auxiliary dead end supports,   c) stringing a first new phase conductor between the set of support structures where the section was moved from,   d) electrically connecting a first transfer bus and a second transfer bus to said first new phase conductor,   e) electrically connecting said second conductor of said first transfer bus and said second conductor of said second transfer bus to a second phase section of a second phase-needing-maintenance that is proximate to said first phase-needing-maintenance, wherein said second phase section comprises a third dead end juncture and a fourth dead end juncture,   f) electrically connecting said first transfer bus so as to bring said first new phase conductor to an electrical potential that is equal to said second phase-needing maintenance,   g) completing a first electrically parallel connection between said first new phase conductor and said second phase-needing-maintenance,   h) electrically connecting said new phase conductor to a first segment of said second phase-needing-maintenance on opposite sides of said third dead end juncture, and electrically connecting said first new phase conductor to a second segment of said second phase-needing-maintenance on opposite sides of said fourth dead end juncture, so as to complete a second electrically parallel connection between said first new phase conductor and said second phase-needing-maintenance,   i) electrically disconnecting said section of said second phase-needing-maintenance so as to isolate said second phase section of said second phase-needing-maintenance from said first and second segments of said second phase-needing-maintenance and said first new phase conductor, and   j) maintaining said second phase section of said second phase-needing-maintenance.   

     Another example embodiment of the present invention provides a method for maintaining sections of electrically conductive phases in a three phase power conductor line, the three phases denoted as the A, B and C phases, wherein the three phases are parallel and spaced apart in an ordered sequence wherein the A phase is proximate to the B phase and the B phase is proximate to the C phase, but the A phase is not proximate to the C phase, and wherein the A, B and C phases are strung between support structures supporting the three phases suspended above a ground, and wherein maintenance work is performed on sections of the three phases without interruption of a power load in any one of the three phases and without transposing the relative positions of the A, B and C phases out of their ordered sequence, wherein at least two equal potential zones are employed in communication with at least one of said A, B and C phases. 
     Another example embodiment of the present invention provides a method of maintaining sections of electrically energized phases in a three phase power conductor line, the three phases being an A phase, a B phase and a C phase, the method comprising:
     a) providing, between two support structures above a ground surface, the A phase is proximate to the B phase, the B phase is proximate to the C phase and the B phase is located between the A phase and the C phase with the phases all in a common plane;   b) without interrupting an alternating current power of the A phase, the B phase and the C phase, performing maintenance work on sections of the A phase, the B phase and the C phase;   c) without interrupting an alternating current power of the A phase, the B phase and the C phase, non-transposing the relative positions of the A phase, the B phase and the C phase; and,   d) employing at least two equal potential zones in conjunction with at least one of said A phase, B phase and C phase.   

     As described in the &#39;132 patent entitled Live Conductor Stringing and Splicing Method and Apparatus, the disclosure of which is incorporated herein by reference in its entirety, a person ordinarily skilled in the art will readily understand how to employ the aforementioned stringing method described above, including the construction of equal potential zones, the use of hot line tools and live line work methods that are described in the &#39;132 patent specification. In particular, see  FIGS.  57  through  98    and column  22 , line  48  through column  33 , line  60  of patent ′ 132 . 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    is a schematic diagram illustrating a power transfer system for transferring power in three electrical phases, one electrical phase being transferred per conductor. 
         FIG.  2    is a side view of a support structure for a power transfer system showing a temporary support structure located proximate to a permanent support structure configured for the temporary relocation of a phase conductor at a distance substantially equal to the phase spacing between the other phase conductors. 
         FIG.  3    is a schematic diagram illustrating the power transfer system of  FIG.  1    showing temporary support structures added in accordance with the invention. 
         FIG.  4    is a side view of the support structure of  FIG.  2   , illustrating the relocation of a phase conductor from its permanent support structure to a temporary location on a temporary support structure. 
         FIG.  5    is a schematic diagram illustrating the power transfer system of  FIG.  3    showing the relocation of a phase conductor to a temporary location on temporary support structures. 
         FIG.  6    is a schematic diagram illustrating the power transfer system of  FIG.  5    showing the relocation of a first dead end to a temporary location. 
         FIG.  7    is a schematic diagram illustrating the power transfer system of  FIG.  6    showing the relocation of a second dead end to a temporary location. 
         FIG.  8    is a schematic diagram illustrating the power transfer system of  FIG.  7    showing new conductor installed between new dead end structures. 
         FIG.  9    is a schematic diagram illustrating the power transfer system of  FIG.  8    showing a first temporary transfer bus partially installed. 
         FIG.  9 A  is a detail view of a portion of the schematic diagram illustrating the power transfer system of  FIG.  9    showing the electrical connection between a first temporary transfer bus and a phase conductor. 
         FIG.  10    is a schematic diagram illustrating the power transfer system of  FIG.  9    showing a second temporary transfer bus partially installed. 
         FIG.  11    is a schematic diagram illustrating the power transfer system of  FIG.  10    showing the first temporary transfer bus fully installed. 
         FIG.  12    is a schematic diagram illustrating the power transfer system of  FIG.  11    showing the second temporary transfer bus fully installed. 
         FIG.  13    is a schematic diagram illustrating the power transfer system of  FIG.  12    showing a new conductor electrically connected to the B phase conductor across the second transfer bus that is connected to a closed breaker. 
         FIG.  14    is a schematic diagram illustrating the power transfer system of  FIG.  13    showing a new conductor connected in parallel to the B phase conductor across two transfer buses that are each connected to a closed breaker. 
         FIG.  15    is a schematic diagram illustrating the power transfer system of  FIG.  14    showing a jumper cable connecting the original B phase conductor to the new phase conductor across a dead end on the B phase conductor and a dead end located between the original A phase conductor and the new conductor. 
         FIG.  16    is a schematic diagram illustrating the power transfer system of  FIG.  15    showing two jumper cables removed from around a dead end on the B phase conductor. 
         FIG.  17    is a schematic diagram illustrating the power transfer system of  FIG.  16    showing a jumper cable connecting the original B phase conductor to the new phase conductor across a dead end on the B phase conductor and a dead end located between the original A phase conductor and the new conductor. 
         FIG.  18    is a schematic diagram illustrating the power transfer system of  FIG.  17    showing two jumper cables removed from around a dead end on the B phase conductor. 
         FIG.  19    is a schematic diagram illustrating the power transfer system of  FIG.  18    showing the breaker connected to the first temporary transfer bus set to the open position and breaking parallel between the new conductor and the original B phase conductor. 
         FIG.  20    is a schematic diagram illustrating the power transfer system of  FIG.  19    showing the breaker connected to the second temporary transfer bus set to the open position and breaking the electrical connection between the new conductor and the original B phase conductor. 
         FIG.  21    is a schematic diagram illustrating the power transfer system of  FIG.  20    showing the second transfer bus disconnected from the breaker and removed from the power transfer system. 
         FIG.  22    is a schematic diagram illustrating the power transfer system of  FIG.  21    showing the first transfer bus disconnected from the breaker and removed from the power transfer system. 
         FIG.  23    is a schematic diagram illustrating the power transfer system of  FIG.  22    showing new conductor installed between dead end structures on the original B phase conductor line. 
         FIG.  24    is a schematic diagram illustrating the power transfer system of  FIG.  23    showing a first and second temporary transfer bus installed between the C phase conductor and the new D phase conductor wherein the two temporary transfer buses are each connected to an open breaker. 
         FIG.  25    is a schematic diagram illustrating the power transfer system of  FIG.  24    showing the new conductor connected in parallel to the C phase conductor across two transfer buses that are each connected to a closed breaker. 
         FIG.  26    is a schematic diagram illustrating the power transfer system of  FIG.  25    showing two jumper cables each connecting the original C phase conductor to the new phase conductor across dead end junctures on the C phase conductor and dead end junctures located between the original B phase conductor and the new conductor and the jumper cables surrounding the two dead end junctures on the original C phase conductor removed. 
         FIG.  27    is a schematic diagram illustrating the power transfer system of  FIG.  26    showing the two breakers each connected to a temporary transfer bus set to an open position breaking parallel between the original C phase conductor and the new conductor. 
         FIG.  28    is a schematic diagram illustrating the power transfer system of  FIG.  27    showing new conductor installed between dead end structures on the original C phase line and the two temporary transfer buses removed from the power transfer system. 
         FIG.  29    is a schematic diagram illustrating the power transfer system of  FIG.  28    showing two temporary transfer buses each connected to a breaker set in the open position and installed between the new D phase conductor and the new C phase conductor. 
         FIG.  30    is a schematic diagram illustrating the power transfer system of  FIG.  29    showing the new D phase conductor connected in parallel to the new C phase conductor across two temporary transfer buses that are each connected to a closed breaker. 
         FIG.  31    is a schematic diagram illustrating the power transfer system of  FIG.  30    showing the removal of the two jumper cables illustrated in  FIG.  30    each connecting the original C phase conductor to the new C phase conductor across dead end junctures and showing the installation of new jumper cables across the two dead end junctures on the new C phase conductor line. 
         FIG.  32    is a schematic diagram illustrating the power transfer system of  FIG.  31    showing each of the two breakers connected to the two temporary transfer buses set to an open position breaking parallel between the new C phase conductor and the D phase conductor. 
         FIG.  33    is a schematic diagram illustrating the power transfer system of  FIG.  32    showing two temporary transfer buses each connected to a breaker set in the open position and installed between the D phase conductor and the new B phase conductor. 
         FIG.  34    is a schematic diagram illustrating the power transfer system of  FIG.  33    showing the D phase conductor connected in parallel to the new B phase conductor across two temporary transfer buses that are each connected to a closed breaker. 
         FIG.  35    is a schematic diagram illustrating the power transfer system of  FIG.  34    showing the removal of the two jumper cables illustrated in  FIG.  34    each connecting the original B phase conductor to the new phase conductor across dead end junctures and showing the installation of new jumper cables across the two dead end junctures on the new B phase conductor line. 
         FIG.  36    is a schematic diagram illustrating the power transfer system of  FIG.  35    showing each of the two breakers connected to the two temporary transfer buses set to an open position breaking parallel between the new B phase conductor and the D phase conductor. 
         FIG.  37    is a schematic diagram illustrating the power transfer system of  FIG.  36    showing two temporary transfer buses each connected to a breaker set in the open position and installed between the D phase conductor and the original A phase conductor located in a temporary position. 
         FIG.  38    is a schematic diagram illustrating the power transfer system of  FIG.  37    showing the D phase conductor connected in parallel to the original A phase conductor across two temporary transfer buses that are each connected to a closed breaker. 
         FIG.  39    is a schematic diagram illustrating the power transfer system of  FIG.  38    showing the removal of the two jumper cables illustrated in  FIG.  38    each connecting the original A phase conductor to the temporarily relocated section of A phase conductor across dead end junctures and showing the installation of new jumper cables across the two dead end junctures on the new A phase conductor line. 
         FIG.  40    is a schematic diagram illustrating the power transfer system of  FIG.  39    showing each of the two breakers connected to the two temporary transfer buses set to an open position breaking parallel between the new A phase conductor and the original A phase conductor. 
         FIG.  41    is a schematic diagram illustrating the power transfer system of  FIG.  40    showing the removal of the two temporary transfer buses and the two breakers from the power transfer system. 
         FIG.  42    is a schematic diagram illustrating the power transfer system of  FIG.  41    showing the removal of the de-energized original A phase conductor from the power transfer system. 
         FIG.  43    is a side view of a temporary transfer bus suspended from two tangent insulators each supported on a phase conductor and connected to a closed breaker with jumper cables. 
         FIG.  44    is a top view of an air break switch in a closed position. 
         FIG.  45    is a top view of an air break switch in an opened position. 
         FIG.  46    is a side view of a portable breaker in accordance with one embodiment of the invention. 
         FIG.  47    is a side view of a support structure for a power transfer system showing a temporary support structure attached to a permanent support structure and insulators configured to carry double conductors (two conductors per phase). 
         FIG.  48    is a side view of a temporary transfer bus suspended from two tangent insulators each supported on a phase conductor and the two rigid conductors of the transfer bus electrically connected to each other by a jumper cable. 
         FIG.  49    is a front elevation view of a support structure for a power transfer system showing three adjacent phases A, B and C. 
         FIG.  50    depicts the addition of a temporary support structure, a transfer of the C phase conductor to the temporary support structure and the stringing of a first replacement conductor where the C phase was moved from. 
         FIG.  51    depicts the transfer of the electrical load from the B phase to the first replacement conductor (D phase) and the stringing of a second replacement conductor where the B phase was located. 
         FIG.  52    depicts the transfer of the electrical load from the A phase to the second replacement conductor (the new conductor strung in  FIG.  51   ) and the stringing of a third replacement conductor where the A phase was located. 
         FIG.  53    depicts the transfer of the electrical load from the second replacement conductor to the third replacement conductor. 
         FIG.  54    depicts the transfer of the electrical load from the first replacement conductor to the second replacement conductor. 
         FIG.  55    depicts the transfer of the electrical load from the C phase conductor to the first replacement conductor. 
         FIG.  56    depicts the three replacement conductors each carrying the three phases A, B and C in the ordered sequence of  FIG.  49   , the temporary support structure and the original C phase having been removed. 
     
    
    
     DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION 
     The invention will now be described with reference to the Figures, in which like reference numerals refer to like parts throughout. An embodiment in accordance with one aspect of the present invention provides an improved method for replacing high-voltage power transmission conductors without affecting power users or power suppliers. The method avoids a requirement of having the power transmitted by the conductors shut off or diverted to other remote power transmissions systems. The method also avoids an illegal transposition of the phase conductors when transferring the power loads from a phase conductor to a proximate phase conductor during the maintenance or repair work, which illegal transposition may otherwise lead to faults in the transmission line. 
     As stated above, power delivery systems such as high voltage power lines often transport Alternating Current (“AC”) power in a three phase configuration. Direct Current (“DC”) power systems transfer power over two phases. Each phase is transferred over a separate conductor. For the purposes of this specification, each of the letters A, B, and C will represent one of three phases of a three-phase AC system. The methods and apparatus described herein can be adapted for use in a DC system by applying the methods and apparatus described herein for the A and B phases for the two phases of a DC system and where reference is made, for example in the claims, to the A, B and C phases, such references are intended to include merely the A and B phases for a DC implementation. Systems carrying voltages of 44 kV or higher are contemplated in the embodiments of the present invention. 
     In addition, throughout this specification there is often reference to a fourth phase conductor, referred to as the “D phase” conductor. The D phase conductor, as that term is used in this specification, denotes a section of a phase conductor that is not electrically connected to any of the phase conductors that are carrying the A, B or C phases. In other words, the D phase is not carrying the current of any of the A, B, or C phases. Throughout the Figures illustrating examples of embodiments of the present invention, a phase conductor labelled as the “D phase” conductor in one figure may be labelled as an A, B or C phase conductor in the next Figure, where the “D phase” conductor becomes electrically connected to another phase conductor carrying the A, B or C phase current. For example, see  FIGS.  12  and  13   , wherein the “D phase” conductor  114  in  FIG.  12    becomes a “B phase” conductor  114  in  FIG.  13   , upon establishing an electrical connection between the conductor  114  and the original B phase conductor  102  (B) when the breaker  142  connected to the second transfer bus  118 ″ is closed. In each Figure of this specification, a phase conductor is either labelled “D phase”, when it is electrically isolated from any other phase conductors in the power transfer system  100 , or it is labelled “A phase”, “B phase” or “C phase” when the phase conductor is carrying the A, B or C phase current, or is otherwise electrically connected to a phase conductor that carries either the A, B or C phase current. 
     In an embodiment of the invention, a section of a first conductor located between two dead end junctures is moved to a temporary position on temporary support structures. The dead end junctures of the section of the first conductor are also transferred to the temporary positions on the temporary support structures. A new conductor is then strung in or near the old conductor&#39;s originating position, and the power load from a first proximate phase-needing-maintenance is transferred to the new conductor. Once the power load from the first proximate phase-needing-maintenance is transferred to the new conductor, a section of the old conductor of the first proximate phase-needing-maintenance is removed and replaced with a second new conductor. Once the second new conductor is in place, the power load of a second proximate phase-needing-maintenance is transferred to the second new conductor, enabling work to be conducted on a section of the second proximate phase-needing-maintenance conductor. This procedure is repeated until all of the proximate phase conductors requiring maintenance work have had their power loads transferred to other phase conductors. Once all of the maintenance work is complete, the power loads of each phase are consecutively transferred to the phase conductors strung into the positions where each phase was originally carried. This procedure provides for maintenance work to be conducted on high voltage transmission lines, without having to interrupt the supply of power to users and avoiding the illegal transposition of the respective phase conductors during the transfer of the power load from one phase conductor to an adjacent phase conductor. 
       FIGS.  1  through  43    generally show, in schematic diagrams, a power transfer system  100  undergoing consecutive stages of a method in accordance with an embodiment of the invention, so that a section of a phase conductor to be worked on may be electrically isolated from the system power. As used herein, the term “maintenance work” includes the replacement of the phase conductor, and may also include maintenance of the conductor, replacement of insulators, resagging of the conductor, all without disrupting the transmission of power to downstream power customers. 
     In many instances there may be miles between dead end junctures. If the distance between the dead end junctures for a particular section of phase conductor to be worked upon is too great for pulling new conductors through the system  100 , then new or temporary dead end junctures may be constructed as described later herein. 
     The temporary relocation of a phase conductor, the stringing of new phase conductor in a position at or near the originating position of the phase conductor, and the process of successively transferring the power load from an adjacent phase to the new conductor such that the next phase may be isolated and worked upon, will now be described with reference to  FIGS.  1 - 43   . 
       FIG.  1    is a schematic diagram for power transfer system  100 . The power transfer system  100  includes three conductors  102 , labeled A phase, B phase and C phase, indicating that each of the conductors  102  carries one of the A, B, or C phase load. The system  100  transfers power in the form of AC, although this is not intended to be limiting as the method described herein may be used for DC power systems. The conductors  102  are supported by support structures  104 . Each support structure  104  may include or be in the form of a power pole or a tower. One example of a support structure  104 , not intended to be limiting, is seen in  FIG.  2   . Other support structures are seen in  FIGS.  53 ,  55  and  56    of the &#39;132 patent. A conductor  102  is attached to dead end support structures  103  via insulators in tension  106  (hereinafter insulators  106 ). As seen in  FIG.  1   , dead end junctures  110 ′,  110 ″ are formed by a pair of insulators  106  when in-line with conductors  102  and under tension with conductors  102 . Jumper cables  108 , as shown in  FIG.  1   , electrically connect conductors  102  around insulators  106  and dead end support structures  103  to an oppositely disposed section of conductors  102 . 
     Another way conductor  102  may be supported by support structure  104  is shown for example in  FIG.  2   . The conductor  102  hangs from tangent insulator  116 . Tangent insulator  116  is supporting both the conductor tension and the weight of conductor  102 . When the weight of conductor  102  is being supported by tangent insulator  116 , jumper cables  108  are not required. 
     In some embodiments of the present invention, a temporary support structure (otherwise referred to as an auxiliary support)  112  is constructed near the location of an existing support structure  104 , as shown in  FIGS.  2  and  3   . The temporary support structure  112  is preferably located near or adjacent the location of an existing support structure  104 , whereby the distance L between the original location  95  and the temporary location  96  of the A phase conductor  102  is substantially equivalent to the phase spacing J between phases A and B and between phases B and C, when those phase conductors,  102  (A),  102  (B) and  102  (C) respectively, are suspended on the existing support structure  104 . The temporary support structure  112  may be located adjacent the existing support structure  104 , or in the alternative the temporary support structure  112  may be connected to the support structure  104  as shown in  FIG.  54    in the &#39;132 patent, for example. 
     Once the temporary support structures  112  are in place, a section  87  of the A phase conductor  102  (A) located between dead end junctures  110 ′ and  110 ″ is removed from the original location  95  on the existing support structures  104  and transferred to the temporary position  96  on the temporary support structure  112 .  FIG.  4    shows the transfer of the A phase conductor  102  (A) from its original location  95  on support structure  104  to the temporary location  96  on temporary support structure  112 , using a robotic mechanical arm device  101 , such as the Remote Manipulator for Manipulating Multiple Sub-conductors in a Single Phase Bundle described in the Applicant&#39;s U.S. Pat. No. 8,573,562, or similar robotic mechanical arm device adapted to manipulate heavy energized conductors such as the A phase conductor  102  (A). 
     As seen in  FIG.  5   , although there are only two temporary support structures  112 , it will be appreciated by a person ordinarily skilled in the art that a section of phase conductor  102  to be replaced may be supported by numerous support structures  104  and that more than two temporary support structures  112  may be required to support the section of the phase conductor  102  that needs to be transferred to a temporary location  96 . Furthermore, it will be appreciated by a person skilled in the art that a section of a different phase conductor, such as a section of the C phase conductor  102  (C) illustrated in  FIG.  3   , may alternatively be moved to a temporary position  96  adjacent the originating position  95  of conductor  102  (C) in accordance with the procedure described above with respect to conductor  102  (A) and that such procedure would be within the scope of the present invention described herein. 
     As illustrated in  FIGS.  6  and  7   , once the section  87  of phase conductor  102  (A) that is the subject of maintenance work has been moved to temporary support structures  112 , each of the dead end junctures  110 ′,  110 ″ at either end of the section  87  of phase conductor  102  (A) are transferred to temporary dead end poles (otherwise referred to as auxiliary dead end supports)  113 ′,  113 ″. It will be readily understood by a person ordinarily skilled in the art, having read this specification, that although two temporary support structures  112 ,  112  are illustrated in  FIG.  7   , that it is possible to carry out the procedure described herein utilizing a single temporary support structure  112 , or otherwise to utilize more than two temporary support structures  112 , to support a section  87  of phase conductor  102  (A). 
     The section  87  of conductor  102  (A) is mounted to the temporary dead end pole  113 ′,  113 ″ while the jumper cable  108  remains attached to the phase conductor  102  (A), such that the power load on the phase conductor  102  (A) continues to be transferred around the dead end juncture  110 ′,  110 ″ by the jumper cables  108  while the section  87  of phase conductor  102  (A) is being relocated.  FIG.  8    shows a first new phase conductor  114  (also referred to as the D phase) strung into the original location  95  of the A phase conductor  102  (A). The first new phase conductor  114  becomes the D phase conductor, as the new phase conductor  114 , with the exception of any induced current caused by the surrounding current-carrying phases, initially does not carry any power load after being strung into place. 
     In many of the schematic diagrams of this patent specification, beginning with  FIG.  8   , an ellipse or a circle is sometimes used to highlight a feature illustrated in the schematic diagram that has been added or which has changed from the immediately preceding Figure. For example,  FIG.  8    shows an ellipse around the new phase conductor  114  strung into the original location  95  of the A phase conductor  102  (A), which is a new feature not illustrated in the immediately preceding  FIG.  7   . It is understood that such ellipses and circles are merely included to clearly illustrate the changes that occur in the sequential steps of a preferred embodiment of the present method invention described herein, and are not themselves representing features of the power transfer system  100 . 
     Once the new phase conductor  114  is in place, the power load is transferred from an adjacent phase conductor  102  to the new D phase conductor  114 . In the example illustrated in  FIGS.  9 - 20   , the B phase load in conductor  102  (B) will be transferred to the D phase conductor  114 . One way to accomplish the power transfer is with a temporary transfer bus  118 ′,  118 ″. 
       FIG.  43    shows a preferred embodiment of a temporary transfer bus  118  constructed of substantially rigid conductors  120 ,  120 , an insulator  94  located between the two conductors  120 ,  120 , arranged in a substantially co-linear relationship with respect to the conductors  120 ,  120 , bus clamps  123 ,  123  and a plurality of connectors  121  for temporarily attaching a jumper cable  108  or other conductor to one of the conductors  120  of the transfer bus  118 . Each of the conductors  120  of the transfer bus  118  are attached to a tangent insulator  116  by means of a bus clamp  123 . Each tangent insulator  116  is suspended from either an existing phase conductor  102  or a new phase conductor  114 . Once the temporary transfer bus  118  is in place, there is no electrical connection between the rigid conductors  120  of the transfer bus  118  due to the intervening transfer bus insulator  94 . An electrical connection may be established across the insulator  94  of the transfer bus  118  by means of a jumper cable  108  attached to one or more of a plurality of connectors  121  located on each of the rigid conductors  120 . Optionally, and as further discussed below and illustrated in  FIG.  43   , the electrical connection across the insulator  94  of the transfer bus  118  may also be established by means of a switch  140  (illustrated in  FIGS.  44  and  45   ) or preferably, a breaker  142 , whereby jumper cables  148 ,  150  are used to connect each of the first and second bushings,  144 ,  146  of the breaker  142  to the first and second rigid conductors  120 ,  120  respectively of the transfer bus  118 . 
     As mentioned above, care must be taken when connecting or disconnecting an energized conductor from another conductor in high voltage applications such as the voltages associated with high voltage power lines, because when the conductors are near each other, either before connection or after the disconnection, a large potential will exist between the energized conductor and the non-energized conductor. Due to the large electrical potential between the conductors, large arcs can form between the conductors if the difference in potential is high enough. 
     Thus, there are three options for establishing and breaking an electrical connection between the rigid conductors  120  of the transfer bus  118  across the insulator  94 . First, live line equipment such as hot sticks may be used to physically connect each end of a jumper cable  108  to a conductor  120  of the transfer bus  118 , as illustrated in  FIG.  48   . Second, a conductor including a switch  140  may be connected to each conductor  120  of the transfer bus  118 . The switch  140  will initially be set in the open position before the connection of the switch to each conductor  120  of the transfer bus  118  is made, and each conductor  120  of the transfer bus  118  may then be connected to a phase conductor  102  or new phase conductor  114  using jumper cables  134  (see  FIGS.  9  and  9     a ) and hot sticks. Once each of the two conductors  120 ,  120  of the transfer bus  118  are electrically connected to either the phase conductor  102  or phase conductor  114 , the switch  140  may be closed to establish the electrical connection between the two conductors  102 ,  114 . Similarly, the third option of establishing an electrical connection between two conductors  120 ,  120  across the insulator  94  of a transfer bus  118  is similar to the second option described above, except that a breaker  142  is used in place of the switch, as shown in  FIG.  43   , and will not be repeated here. 
     Which method to use, the hot sticks and jumper cable, the switch or the breaker depends on several factors. Two factors to consider are the electrical potential between the conductors to be connected and the mass of the non-energized conductor that is to be connected to the energized conductor across the transfer bus  118 . If the mass of the conductor to be connected and/or the voltage potential is relatively minor, the two conductors may be connected across the transfer bus by a jumper cable  108  using hot sticks. As the mass of the conductor to be connected to the energized conductor increases and/or the voltage difference between the two conductors increases, a switch may be used to establish the electrical connection across the insulator  94  of the transfer bus  118 ; finally, with conductors having a large mass and/or a large voltage potential between the conductors, a breaker  142  is used to establish the connection across the insulator  94  of the transfer bus  118 . In the preferred embodiment of the method described below, which is not intended to be limiting in any way, the electrical connection is established across the insulator  106  of the transfer bus  118  by means of a breaker  142 ; however, it will be well understood by a person ordinarily skilled in the art that the electrical connection may also be established across the insulator  94  of the transfer bus  118  by means of a switch  140  or by means of a length of a conductor, such as for example a jumper cable  108 , depending on factors which include the electrical potential and the mass of the non-energized conductor that is to be connected to an energized conductor, as described above. 
     Once the D phase conductor  114  is in place, the power load is transferred from the conductor  102  (B) of the B phase line onto the D phase conductor  114  over the course of several steps.  FIG.  9    shows that one rigid conductor  120  of a first transfer bus  118 ′ is electrically connected to the D phase conductor  114  by means of a jumper cable  134 .  FIG.  10    shows one rigid conductor  120  of a second transfer bus  118 ″ is electrically connected to the D phase conductor  114  by means of a second jumper cable  134 . In  FIGS.  9  and  10   , although it appears that the rigid conductors  120  of each of the transfer buses  118 ′,  118 ″ that are opposite of the rigid conductors  120  connected to the D phase conductor  114  by means of the jumper cables  134 ,  134  are in close proximity to the B phase conductor  102  (B), there is no physical or electrical connection between those rigid conductors  120  of the transfer buses  118 ′,  118 ″ and the B phase conductor  102  (B), as the transfer buses  118 ,  118  are positioned either above, or preferably, below the B phase conductor  102  (B). 
     As illustrated in  FIGS.  11  and  12   , once the breaker  142  of each transfer bus  118 ′,  118 ″ is confirmed to be set in the open position, a jumper cable  134  is used to electrically connect a rigid conductor  120  of each transfer bus  118 ′,  118 ″ to a section  90  of the B phase conductor  102  (B) located between two dead end junctures  110 ′,  110 ″. As illustrated in  FIG.  12   , once the first rigid conductors  120  of each transfer bus  118 ′,  118 ″ are each connected to the D phase conductor  114  and the second rigid conductors  120  of each transfer bus  118 ′,  118 ″ are connected to the B phase conductor  102  (B), the breaker  142  on each transfer bus  118 ′,  118 ″ remains in the open position and therefore the D phase conductor  114  remains de-energized. 
     In  FIG.  13   , the breaker  142  of transfer bus  118 ″ is closed, thereby establishing an electrical connection between the energized B phase conductor  102  (B) and the new phase conductor  114 , whereby the new phase conductor  114  is brought to the same voltage potential difference as the B phase conductor  102  (B). Because the new phase conductor  114  shown in  FIG.  13    is connected to the B phase conductor  102  (B) at only one location, current is flowing only over the B phase conductor  102  (B) and not over the new phase conductor  114 . The new phase conductor  114  has the same electrical potential as the B phase conductor  102  (B), but the new phase conductor  114  does not yet transport a power load. 
     In order for current to flow through the new phase conductor  114 , the breaker  142  of the transfer bus  118 ′ must be closed, as shown in  FIG.  14   . Once the breakers  142 ,  142  on each of the transfer buses  118 ′,  118 ″ are closed, a parallel path is created for the B phase current to run through both the new phase conductor  114  and the original B phase conductor  102  (B). 
     As illustrated in  FIG.  15   , at one of the dead end juncture  110 ′ on opposite ends of section  90  of the original B phase conductor  102  (B), one end of a long jumper cable  111  is connected to a section  91  of the original B phase conductor  102  (B) that is oppositely disposed on dead end juncture  110 ′, and the other end of the long jumper cable  111  is connected to the new phase conductor  114 , creating a parallel connection for the B phase current to flow around the dead end juncture  110 ′. As shown in  FIG.  16   , jumper cables  108 ,  108  are removed from around one dead end juncture  110 ′ on the B phase conductor  102  (B). The removal of the jumper cables  108 ,  108  can, if the voltage and/or the mass of the conductor  102  (B) is low enough, be removed by using hot sticks. If the voltage and/or mass of the conductor  102  (B) are too high, other means of breaking the connection around the dead end juncture  110 ′ may be used which may include a switch or breaker described in greater detail above. 
     As shown in  FIG.  17   , at the second dead end juncture  110 ″ on the opposite end of the section  90  of the original B phase conductor  102  (B), one end of a long jumper cable  111  is connected to a section (or otherwise referred to as a “segment”)  92  of the B phase conductor  102  (B) that is oppositely disposed of dead end juncture  110 ″, and the other end of the long jumper cable  111  is connected to the new phase conductor  114 , creating a parallel connection for the B phase current to flow around the second dead end juncture  110 ″. As shown in  FIG.  18   , jumper cables  108 ,  108  are removed from around the second dead end juncture  110 ″ of the original B phase conductor  102  (B). 
     In  FIG.  19   , the breaker  142  of transfer bus  118 ′ is opened. The effect of opening one breaker  142  is that the current no longer flows through the section  90  of the original B phase conductor located between the dead end junctures  110 ′,  110 ″. All of the B phase current now flows through the new conductor  114  rather than the original B phase conductor  102  (B). However, because the breaker  142  of the other transfer bus  118 ″ remains closed, an electrical connection still exists between the original B phase conductor  102  (B) and the new conductor  114  at one point; therefore, the electrical potential between the original B phase conductor  102  (B) and the new phase conductor  114  remains the same. 
     To electrically isolate the section  90  of the original B phase conductor  102 , the breaker  142  of the second transfer bus  118 ″ is opened, as shown in  FIG.  20   . In other embodiments of the present invention, if the voltage and/or the mass of the original B phase conductor  102  is low enough, either a switch or a jumper cable may be substituted for the breaker  142  to establish and break the electrical connection between the rigid conductors  120 ,  120  of the transfer bus  118 ″. Upon opening the second transfer bus  118 ″, section  90  of the original B phase conductor becomes electrically isolated from the system (except for currents which may be induced in section  90  of phase conductor  102  due to the electromagnetic effects of the surrounding current-carrying phase conductors), and the original B phase conductor therefore becomes the D phase conductor, as it no longer carries the B phase current or any phase current of the power transfer system  100 . 
     One of the jumper cables  134  connecting a first end of the transfer bus  118 ″ to the new B phase conductor  114  is removed, de-energizing the open breaker  142 . The second jumper cable  134  connecting a second end of the transfer bus  118 ″ to the original B phase conductor  102  (which is now de-energized and therefore has become the D phase conductor  102 ) is also removed, and the temporary transfer bus  118 ″ is then removed from the power transfer system  100 , as illustrated in  FIG.  21   . Similarly, the two jumper cables  134 ,  134  connecting the transfer bus  118 ′ at the first end to the new B phase conductor  114  and at the second end to the D phase conductor  102  are removed, and then the transfer bus  118 ′ is removed from the power transfer system  100 , as shown in  FIG.  22   . 
     The section  90  of the D phase conductor  102  between the dead end junctures  110 ′,  110 ″ is now isolated from all B phase potential by both dead end junctures  110 ′,  110 ″. All current formerly carried by the D phase conductor  102  now travels through the new B phase conductor  114 . It is important to note that section  90  of the D phase conductor  102 , now isolated from the system  100  power load, is not void of potential. The isolated section  90  of the D phase conductor  102  is, and should be treated as, a live conductor, because the isolated section  90  of the D phase conductor  102  is subject to induced currents caused by the surrounding current-carrying phase conductors  102 ,  114  and may still have a large potential with respect to ground. 
     At this stage in the procedure, the isolated section  90  of the original B phase conductor may be broken down, worked on, or replaced without disrupting downstream power delivery. For example, as illustrated in  FIG.  23   , the section  90  of the original B phase conductor  102  is removed and a second new phase conductor  115  is strung, sagged, dead ended and clipped into the position of the original B phase conductor  102 . In some embodiments of the invention, the original B phase line  102  is not removed but is rather worked on in other ways, such as replacing an insulator  106 . One skilled in the art can appreciate that other types of work may be done on the isolated section  90  of the B phase conductor  102  in accordance with the invention. 
     The above describes the procedure, illustrated in  FIGS.  1 - 23   , for moving the A phase conductor  102  (A) to a temporary location  96 , stringing a first new phase conductor  114  in or near the original location  95  of the A phase conductor  102  (A), transferring the power load from the B phase conductor  102  (B) to the D phase conductor  114 , electrically isolating the section  90  of the B phase conductor  102  (B) located between two dead end junctures  110 ′,  110 ″ from the power transfer system  100 , and replacing the electrically isolated section  90  of the B phase conductor  102  with a second new phase conductor  115 . The procedure for transferring the power load from the C phase conductor  102  (C) to the new D phase conductor  115  in accordance with the invention, described below and illustrated in  FIGS.  24 - 28   , is similar to the procedure for transferring the power load from the B phase conductor  102  (B) to the new phase conductor  114  described above. 
     As shown in  FIG.  24   , a section  97  of the C phase conductor  102  (C), located between two dead end junctures  110 ′,  110 ″ requires replacement or other maintenance or repair work. A first transfer bus  118 ′, with a breaker  142  connected to each of the two rigid conductors  120  of the transfer bus  118 , is connected at one end to the D phase conductor  115  with a jumper cable  134 , and the opposite end of the first transfer bus  118 ′ is connected to the section  97  of the C phase conductor  102  (C) with a second jumper cable  134 . A second transfer bus  118 ″ with a breaker  142  connected to each of the two rigid conductors  120  of the transfer bus  118 ″, is connected at one end to the D phase conductor  115  with a third jumper cable  134 , and the opposite end of the second transfer bus  118 ″ is connected to the section  97  of the C phase conductor  102  (C) with a fourth jumper cable  134 . The electrical connections described above between the transfer buses  118 ′,  118 ″ and the phase conductors  115 ,  102  (C) are established after first checking to confirm that the breaker  142  attached to each transfer bus  118 ′,  118 ″ is open. 
     The breaker  142  attached to the first transfer bus  118 ′ is closed, thereby energizing the new phase conductor  115  at the same electrical potential as the C phase conductor  102  (C). However, because an electrical connection between the new D phase conductor  115  and the C phase conductor  102  (C) has only been established through the first transfer bus  118 ′, although the new phase conductor  115  is energized it does not carry any current. The breaker  142  attached to the second transfer bus  118 ″ is then closed, bringing the new phase conductor  115  in parallel with the C phase conductor  102  (C). Upon closing the breakers  142 ,  142  on each of the transfer buses  118 ′,  118 ″, the C phase current runs in parallel on both the new phase conductor  115  and the C phase conductor  102  (C), as illustrated in  FIG.  25   . 
     Once the C phase current is carried in parallel over the new phase conductor  115  and the original C phase conductor  102  (C), the section  97  of the original C phase conductor  102  (C) located between two dead end junctures  110 ′,  110 ″ is electrically isolated from the power transfer system  100 . As shown in  FIG.  26   , at the first dead end juncture  110 ′ a first long jumper cable  111  is connected at a first end to a first section  98  of the original C phase conductor  102  (C) extending from the first dead end juncture  110 ′ oppositely to section  97 , and a second end of the first long jumper cable  111  is connected to the new phase conductor  115 , establishing a parallel path around the first dead end juncture  110 ′ for the C phase current to flow. Similarly, at the second dead end juncture  110 ″ a second long jumper cable  111  is connected at a first end to a second section  99  of the original C phase conductor  102  (C) extending from the second dead end juncture  110 ″ oppositely to section  97 , and a second end of the second long jumper cable  111  is connected to the new phase conductor  115 , establishing a parallel path around the second dead end juncture  110 ″ for the C phase current. 
     The breaker  142  connected to the first transfer bus  118 ′ is opened, breaking the parallel circuit between the original C phase conductor  102  and the new phase conductor  115 . However, the section  97  of the original C phase conductor  102  remains at the same electrical potential as the new phase conductor  115  until the breaker  142  connected to the second transfer bus  118 ″ is opened, as illustrated in  FIG.  27   . When each of the breakers  142 ,  142  connected to the transfer buses  118 ′,  118 ″ are open, the section  97  of the original C phase conductor  102  is electrically isolated from the new C phase conductor  115  and becomes the D phase conductor. Although the D phase conductor  102  is de-energized at this stage of the reconductoring or maintenance procedure, it is again important to note that section  97  of the original C phase conductor  102 , while isolated from the system  100  power load, is not void of potential. The isolated section  97  of the original C phase conductor  102  is, and should be treated as, a live conductor, because the isolated section  97  of the original C phase conductor  102  is subject to induced currents caused by the surrounding current-carrying phase conductors  102  (C),  115 ,  114  and may still have a large potential with respect to ground. 
     The isolated section  97  of the original C phase conductor  102  may be broken down, worked on, or replaced without disrupting downstream power delivery. For example, as illustrated in  FIG.  28   , the two transfer buses  118 ′,  118 ″ are removed, section  97  of the original C phase conductor  102  is removed, and a third new phase conductor  117  is strung, sagged, dead ended and clipped into the position of the original C phase conductor  102 . In some embodiments of the invention, the original C phase line  102  is not removed but is rather worked on in other ways, such as replacing an insulator  106 . One skilled in the art will appreciate that other types of work may be done on the isolated section  97  of the phase conductor  102  within the scope of the invention. 
     Once the reconductoring, maintenance and/or repair work is completed on the sections of the A, B and C phase conductors located between the dead end junctures  110 ′,  110 ″, the power load may be transferred to conductors located in the originating positions of the A, B and C phase conductors, as described below and illustrated in  FIGS.  29 - 42   . 
     As illustrated in  FIG.  29   , a first transfer bus  118 ′ attached to an open breaker  142  is connected at a first end of the transfer bus  118 ′ to the new D phase conductor  117  using a jumper cable  134 , and a second end of the transfer bus  118 ′ is connected to the new phase conductor  115  using a second jumper cable  134 . A second transfer bus  118 ″ attached to an open breaker  142  is connected at a first end of the transfer bus  118 ″ to the new D phase conductor  117  using a third jumper cable  134 , and a second end of the second transfer bus  118 ″ is connected to the C phase conductor  115  using a fourth jumper cable  134 . 
     As illustrated in  FIG.  30   , the breaker  142  attached to the first transfer bus  118 ′ is then closed, thereby energizing the new D phase conductor  117  and bringing the new D phase conductor  117  to the same electrical potential as the C phase conductor  115 . The breaker  142  attached to the second transfer bus  118 ″ is closed, thereby bringing the new D phase conductor  117  into parallel with the C phase conductor  115 , whereby the C phase current flows through both the C phase conductor  115  and the D phase conductor  117 , as shown in  FIG.  30   . 
     Next, as illustrated in  FIG.  31   , two jumper cables  108 ,  108  are used to connect the section  98  of the original C phase conductor  102  (C) opposite the new phase conductor  117  across the first dead end juncture  110 ′ to the new phase conductor  117 . Two additional jumper cables  108 ,  108  are used to connect the section  99  of the original C phase conductor  102  (C) opposite the new phase conductor  117  across the second dead end juncture  110 ″ to the new C phase conductor  117  across the second dead end juncture  110 ″. Once the permanent jumper cables  108  are in place, the temporary long jumper cables  111 ,  111  connecting each of the sections  98 ,  99  of the original C phase conductor  102  to the C phase conductor  115  are removed. The connection of the jumper cables  108  and the disconnection of the temporary long jumper cables  111  is accomplished using live line equipment, such as hot sticks. Once this jumpering procedure is complete, whereby the new permanent jumper cables  108  are installed and the temporary long jumper cables  111  are removed, the C phase current continues to flow in parallel through both the new C phase conductor  117  and the phase conductor  115 , through the circuit path provided by the closed breakers  142  on the two temporary transfer buses  118 ′,  118 ″ as shown in  FIG.  31   . 
     The breaker  142  connected to the first transfer bus  118 ′ is then opened, thereby breaking the parallel circuit between the new C phase conductor  117  and the phase conductor  115 . However, the phase conductor  115  remains energized and at the same electrical potential as the new C phase conductor  117 . The breaker  142  connected to the second transfer bus  118 ″ is then opened, thereby de-energizing the phase conductor  115 , which becomes the D phase conductor because the phase conductor  115  no longer carries the C phase current, or any phase current, as illustrated in  FIG.  32   . At this stage, the two temporary transfer buses  118 ′,  118 ″ may be removed from the power transfer system  100 . Although the phase conductor  115  is de-energized and is not carrying current at this point in the reconductoring procedure, it must still be treated as a live conductor because the isolated D phase conductor  115  is subject to induced currents caused by the surrounding current-carrying phase conductors  114 ,  117  and may still have a large potential with respect to ground. 
     As illustrated in  FIG.  33   , two temporary transfer buses  118 ′,  118 ″ connected to breakers  142 ,  142  set in the open position are temporarily installed between the D phase conductor  115  and the B phase conductor  114 , by utilizing jumper cables  134  to firstly connect a first end of each transfer bus  118 ′,  118 ″ to the D phase conductor  115  near each of the dead end junctures  110 ′,  110 ″, and then secondly using jumper cables  134  to connect a second end of each transfer bus  118 ′,  118 ″ to the B phase conductor  114  near each of the dead end junctures  110 ′,  110 ″. Once the temporary transfer buses  118 ′,  118 ″ are installed with the breakers  142 ,  142  remaining open, the B phase current continues to flow through the sections  91 ,  92  of the original B phase conductor  102  (B) opposite of the D phase conductor  115  on opposing sides of the dead end junctures  110 ′,  110 ″ and through the B phase conductor  114 . As such, the B phase current continues to bypass the D phase conductor  115  while the breakers  142 ,  142  remain open. 
     The breaker  142  connected to the first temporary transfer bus  118 ′ is closed, energizing the D phase conductor  115  and bringing the phase conductor  115  to the same electrical potential difference as the B phase conductor  114 . The breaker  142  connected to the second temporary transfer bus  118 ″ is closed, thereby providing a parallel path for the B phase current to flow through both the phase conductors  114  and  115 , as illustrated in  FIG.  34   . Once each of the two breakers  142 ,  142  connected to the two transfer buses  118 ′,  118 ″ are closed, the B phase current flows through the section  91  of the original B phase conductor  102  (B) opposite the new phase conductor  115  across the first dead end juncture  110 ′, through the long jumper cable  111  to the B phase conductor  114 , through the temporary transfer buses  118 ′,  118 ″ and the closed breakers  142 ,  142  to the new B phase conductor  115 , and through the second long jumper cable  111  to the section  92  of the original B phase conductor  102  (B) located opposite the new phase conductor  115  across the second dead end juncture  110 ″. 
     As illustrated in  FIG.  35   , two jumper cables  108 ,  108  are used to connect the section  91  of the original B phase conductor  102  (B) opposite the new phase conductor  115  across the first dead end juncture  110 ′ to the new B phase conductor  115 . Two additional jumper cables  108 ,  108  are used to connect the section  92  of the original B phase conductor  102  (B) opposite the new phase conductor  115  across the second dead end juncture  110 ″ to the new phase conductor  115 . Once the permanent jumper cables  108  are in place, the temporary long jumper cables  111 ,  111  connecting each of the sections  91 ,  92  of the original B phase conductor  102  (B) to the new B phase conductor  115  are removed. The connection of the jumper cables  108  and the disconnection of the temporary long jumper cables  111  is accomplished using live line equipment, such as hot sticks. Once this jumpering procedure is complete, whereby the new permanent jumper cables  108  are installed and the temporary long jumper cables  111 ,  111  are removed, the B phase current continues to flow in parallel through both the new B phase conductor  115  and the B phase conductor  114 , through the path provided by the closed breakers  142 ,  142  connected to each of the two temporary transfer buses  118 ′,  118 ″, shown in  FIG.  35   . 
     The breaker  142  connected to the first transfer bus  118 ′ is then opened, thereby breaking the parallel circuit between the new B phase conductor  115  and the phase conductor  114 . However, the phase conductor  114  remains energized and at the same electrical potential as the new B phase conductor  115  once only one of the breakers  142  connected to the transfer buses  1181 ,  118 ″ has been opened. The breaker  142  connected to the second transfer bus  118 ″ is then opened, thereby de-energizing the phase conductor  114 , which becomes the D phase conductor because the phase conductor  114  no longer carries the B phase current, as shown in  FIG.  36   . At this stage, the two temporary transfer buses  118 ′,  118 ″ may be removed from the power transfer system  100 . Although the phase conductor  114  is de-energized and is not carrying current at this point in the reconductoring procedure, it must still be treated as a live conductor because the electrically isolated phase conductor  114  is subject to induced currents caused by the surrounding current-carrying phase conductors  115 ,  102  (A) and may still have a large potential with respect to ground. 
     As illustrated in  FIG.  37   , a first transfer bus  118 ′ connected to an open breaker  142  is connected at one end of the transfer bus  118 ′ to the D phase conductor  114  using a jumper cable  134 , and a second end of the first transfer bus  118 ′ is connected to the original A phase conductor  102  (A) using a second jumper cable  134 . A second transfer bus  118 ″ connected to an open breaker  142  is connected at a first end of the transfer bus  118 ″ to the D phase conductor  114  using a third jumper cable  134 , and a second end of the second transfer bus  118 ″ is connected to the original A phase conductor  102  (A) using a fourth jumper cable  134 . 
     The breaker  142  connected to the first transfer bus  118 ′ is then closed, thereby energizing the D phase conductor  114  and bringing the D phase conductor  114  to the same electrical potential as the original A phase conductor  102  (A). The breaker  142  connected to the second transfer bus  118 ″ is closed, thereby bringing the new phase conductor  114  into parallel with the original A phase conductor  102  (A), whereby the A phase current flows through both the original A phase conductor  102  (A) and the new A phase conductor  114 , as shown in  FIG.  38   . 
     As illustrated in  FIG.  39   , two jumper cables  108 ,  108  are used to connect the section  88  of the original A phase conductor  102  (A) located opposite the new A phase conductor  114  across the first dead end juncture  110 ′ to the new A phase conductor  114 . Two additional jumper cables  108 ,  108  are used to connect the section  89  of the original A phase conductor  102  (A) located opposite the new A phase conductor  114  across the second dead end juncture  110 ″ to the new A phase conductor  114 . Once the permanent jumper cables  108  are in place, the temporary long jumper cables  111 ,  111  connecting each of the sections  88 ,  89  of the original A phase conductor  102  (A) to the new A phase conductor  114  are removed. The connection of the jumper cables  108  and the disconnection of the temporary long jumper cables  111  is accomplished using live line equipment, such as hot sticks. 
     Once this jumpering procedure is complete, whereby the new permanent jumper cables  108  are installed and the temporary long jumper cables  111  are removed, the A phase current continues to flow in parallel through both the new A phase conductor  114  and the original A phase conductor  102  (A), through the path provided by the closed breakers  142  connected to each of the two temporary transfer buses  118 ′,  118 ″ as shown in  FIG.  39   . 
     The breaker  142  connected to the first transfer bus  118 ′ is then opened, thereby breaking the parallel circuit between the new A phase conductor  114  and the original A phase conductor  102  (A). However, the original A phase conductor  102  remains energized and at the same electrical potential as the new A phase conductor  114 . The breaker  142  connected to the second transfer bus  118 ″ is then opened, thereby de-energizing the original A phase conductor  102  (A), which becomes the D phase conductor because the original A phase conductor  102  (A) no longer carries the A phase current or any other current, as illustrated in  FIG.  40   . 
     At this stage, the two temporary transfer buses  118 ′,  118 ″ and the breakers  142 ,  142  connected to the transfer buses  118 ′,  118 ″ may be removed from the power transfer system  100 , as illustrated in  FIG.  41   . Although the original A phase conductor  102  (A), which is de-energized and is not carrying current at this point in the reconductoring procedure and has therefore become the D phase, it must still be treated as a live conductor because the electrically isolated phase conductor  102  is subject to induced currents caused by the surrounding current-carrying phase conductor  114  and may still have a large potential with respect to ground. As shown in  FIG.  42   , the original A phase conductor  102  (A) may be removed from the temporary support structures  112 ,  112 ; optionally, the temporary support structures  112  may also be removed from the power transfer system  100 . 
     As a person ordinarily skilled in the art will appreciate, the improved method for conducting repairs and maintenance on live conductors described herein provides the ability to replace, maintain or repair one or more phase conductors without interrupting the supply of power to downstream customers by relocating a section of a phase conductor located between two dead end junctures to a temporary location, transferring the power load from a section of an adjacent conductor located between two dead end junctures to the temporarily relocated conductor, performing maintenance or repair work on the adjacent conductor, or in the alternative, replacing the adjacent conductor with a new conductor, and then repeating the steps of transferring power loads and conducting repair, maintenance or replacement on each adjacent conductor until all of the desired repair, maintenance or replacement work is complete. 
     Importantly, this improved method described herein enables repair, maintenance or replacement work to be conducted on live conductors while avoiding the illegal transposition of the phase conductors throughout the entire procedure. Because of the effect of induced currents and impedance on a phase conductor caused by the close proximity of additional live phase conductors, it is possible that transposing one phase conductor with respect to the other phase conductors may result in an electrical surge in one or more of the phase conductors, which in turn may trip a protective relay and result in the disruption of power delivery to downstream customers. 
     By way of illustrating an example of illegal transposition, consider three phase conductors carrying phases A, B and C that are arranged horizontally with respect to each other in the following order: A-B-C. In the method described herein, as illustrated in  FIGS.  1 - 42   , the relative position of each of the phase conductors, “A-B-C”, remains the same at each step of the re-conductoring procedure. In other words, at no point during the procedure described herein does the relative positions of the A, B and C phase conductors change from the original A-B-C relative arrangement; that is, at no point in the example illustrated and described herein does the method result in transposition of the phase conductors to, for example, an A-C-B arrangement or a C-A-B arrangement or any other transposed arrangement. 
     Furthermore, in the example of the procedure described herein and illustrated in FIGS. 1-42 (see in particular,  FIGS.  4  and  5   ), the A phase conductor  102  is relocated to temporary position  96  at a distance L from the originating position  95  of the A phase conductor  102 , wherein the distance L is substantially equal to the phase spacing distance J between C phase conductor  102  and B phase conductor  102 , and L is also substantially equal to the phase spacing distance J between B phase conductor  102  and the originating position  95  of the A phase conductor  102 . Temporarily relocating A phase conductor  102  to a temporary position  96  at a distance L from the originating position  95  that is substantially equal to the existing phase spacing J between the A, B and C phase conductors minimizes the induced current and resulting impact on the impedance on the phase conductors A, B and C that may otherwise occur if distance L was substantially shorter or longer than phase spacing J, and/or if the positions of any of the phase conductors A, B and C were to be transposed from their original A-B-C relative positioning at any point during the maintenance and repair work described herein. 
     An example of a procedure for stringing a de-energized, new phase conductor into a transmission system, such as for example the D phase conductor  114  illustrated in  FIG.  8   , involves connecting a traveler to a support structure, stringing a pull line (or pulling line) with at least one non-conductive end through the traveler, connecting the pull line via a swivel and a flexible isolator to the conductor, pulling the pull line through the traveler and thereby causing the conductor to be strung through the traveler, attaching the conductor to the support structure, removing the traveler from the support structure, and disconnecting the pull line from the conductor. It is known by a person ordinarily skilled in the art to use a di-electric tested section of rope installed between the pulling line and the new conductor being strung onto the support structure to provide the non-conductive end of the pull line. The Applicant recently filed U.S. application Ser. No. 14/664,724 filed on Mar. 20, 2015, entitled Flexible Electrical Isolation Device, the disclosure of which is incorporated herein in its entirety, describes a flexible elongated insulator having couplings mounted at either end of the insulator. This isolation device, otherwise referred to as a flexible isolator or flexible insulator, consists of a flexible, bendable or otherwise deformable (herein collectively referred to as flexible) member to accommodate the bending radius of a traveler and is composed of a high tensile strength, dielectric material with attachment points, or couplings, on each end. The attachment points or couplings are constructed so as to control both rotation imparted by the cables and bi-directional shear induced when the couplings or attachment points pass through the conductive travelers. 
     A switch  140  may be used in place of the breaker for lighter applications. Operation using the switch in place of a breaker is basically the same and will not be repeated. The switch  140  is a typical air break disconnect switch. It has a disconnect blade  141  that can be operated to a closed position (see  FIG.  44   ) and an open position (see  FIG.  45   ). The switch  140  has connectors  145  on each end that permits conductors  120 ,  120  of the transfer bus  118  to be electrically connected to the switch  140 . When the disconnect blade  141  is in the closed position, it provides an electrical connection between the two conductors  120 ,  120  via the switch  140 . When the disconnect blade  141  is in the open position, there is no electric connection between the two conductors  120 ,  120 . 
     The switch  140  has an actuator  143  that operates the disconnect blade  141 . The opening and closing of the switch is controlled by the actuator  143 . The switch  140  is supported on a frame  147  that provides mechanical support for the switch  140 . The frame  147  is insulated from the conductors by insulators  149 . According to some embodiments of the invention, the switch  140  may be mounted on temporary support structure or a lift apparatus, such as a boom of a vehicle or, for example, preferably a robotic mechanical arm device  101  adapted to manipulate heavy energized conductors such as the phase conductors  102  described in the Applicant&#39;s U.S. Pat. No. 8,573,562, for ease and convenience in practicing some embodiments of the invention. 
     The breaker  142  shown schematically in  FIGS.  9 - 40  and  43    will now be further illustrated and described with reference to  FIG.  46   . In some embodiments of the invention, the breaker  142  is a single pole (phase) of a 345 kV breaker that has been modified to be portable. A typical breaker of this magnitude consists of three single pole breakers mechanically connected together to be a three phase breaker and break all three circuits at once. The three phase breaker includes three breakers connected together and configured to act in unison. Because only a single phase needs to be disconnected or energized at once in many embodiments of the invention, only one pole (or phase) of a breaker is needed. To make the breaker more portable, one pole is separated from the three phase unit and modified to be portable as described in more detail below. 
     A breaker  142  in accordance with the invention may be, as an example not intending to be limiting, a 2,000 amp SF 6  breaker wherein SF 6  is an insulating gas that is used in the breaker  142 . In other embodiments of the invention, the breaker  142  could be a minimum oil breaker, or any other breaker suited to the applied voltage. The breaker  142  has two insulated bushings  144 ,  146  projecting from a housing  156 . Jumpers  148 ,  150  are attached to an end of the bushings  144 ,  146  for connecting the breaker  142  to conductors. 
     The breaker  142  has a closed position that permits an electrical connection from a conductor connected to one bushing  144  via jumper  148  through the breaker  142  to a conductor connected to the other bushing  146  via jumper  150 . When it is desired to break the electrical connection between the two conductors  120 ,  120  of the transfer bus  118 , the breaker  142  is operated to achieve an open position. In the open position, the two jumpers  148 ,  150  connected to the two bushings  144 ,  146  are isolated from each other. 
     Normally, a breaker  142  having the capacity for high voltage power is located in fixed locations, such as for example power generating faculties, terminals, switching stations or substations, and consists of three poles or phases. In accordance with the invention, a standard breaker  142 , such as a 345 kilovolt, 2,000 amp SF 6  breaker, is used. Because these types of breakers have three poles or phases, a single pole or phase is separated out from the other two phases and is modified so as to be portable. As shown in  FIG.  46   , the breaker  142  is mounted onto a trailer  158 . A support structure  160  mounts the breaker  142  to the trailer  158 . Optionally, the breaker  142  could be mounted on a truck bed or some other suitable type of vehicle. 
     The breaker  142  has a housing  156  from which two insulated bushings  144 ,  146  project. One of the bushings  144  is located on what is referred to as the line side  162 , meaning that that bushing  144  connects to the conductor, for example phase conductor  102 , that is connected to a power source. The other side  164  of the breaker  142  is referred to as the load side  164  and includes the other bushing  146 . Within the housing  156  a non-conductive gas, SF 6  for example, is used for electrical insulation. Other breakers in accordance with the invention may be oil-filled breakers or other types of breakers suitable for the applied voltage. 
     A control panel  166  for operating the breaker  142  is located on the trailer  158  and operatively connected to the breaker  142 . Optionally, the control panel  166  may be the same one that would normally operate a standard non-portable breaker. A portable power generator  168  is located on the trailer  158  and is operatively connected to the breaker  142  and/or control panel  166  to provide power to operate the breaker  142 . The generator  168  may be gasoline powered and is of sufficient capacity to permit operation of the breaker  142 , including charging of the springs in the breaker  142 . Preferably, the generator  168  can produce 120 volts. 
     Additional containers  170  of SF 6  gas are kept on the trailer  158  in order to permit recharging of the breaker  142  with gas if necessary. The manufacturer&#39;s recommendations for gas pressure in the breaker  142  should be observed. 
     The exact modifications necessary to make the breaker  142  portable will vary depending on the type of breaker is being modified. A person ordinarily skilled in the art after reviewing this disclosure will be able to appropriately fashion a portable breaker  142 . 
     Before use of the breaker  142 , the tow vehicle is detached and the trailer  158  is held in place by jacks  172  and a wheel chocks  174 . The trailer  158  and the breaker  142  is bonded to ground with grounding cables  176 . A temporary protective fence  178  is constructed around the trailer  158 . 
       FIGS.  49  to  56    depict a method of replacing energized high-voltage power transmission conductors while they remain energized. 
       FIG.  49    is a front, elevation view of a schematic of a support structure  104  that is supporting three phases of conductors  102 A,  102 B and  102 C by insulators  116 . Each of the conductors  102 A,  102 B and  102 C carry an electrical load. The A phase conductor  102  A is positioned on the support structure  104  in a first conductor position  400 . The B phase conductor  102 B is positioned on the support structure  104  in a second conductor position  402 . The C phase conductor  102 C is positioned on the support structure  104  in a third conductor position  404 . The configuration of the support structure  104  depicted in  FIGS.  49  to  56    and, in particular the first, second and third conductor positions  400 ,  402 ,  404  may be in different positions upon the support structure  104  and the positions depicted are not intended to be limiting. While the first, second and third conductor positions  400 ,  402 ,  404  are depicted as being in one single, horizontal plane, these positions can be in a single plane that is not horizontal, for example it may be substantially vertical or between a horizontal plane and a vertical plane or may not be in a single plane at all. The ordered sequence of the three phases of conductors  102 A,  102 B and  102 C is maintained with the conductor  102 A adjacent conductor  102 B but not adjacent conductor  102 C. Conductor  102 B is adjacent, or in between, both of conductor  102 A and conductor  102 C. 
       FIG.  50    depicts a step of installing, providing, or using an existing temporary structure  112  along side the support structure  104 . In this example, the temporary structure  112  provides a fourth conductor position  406 . The C phase conductor  102 C is transferred in step  200  from the support structure  104  to the fourth conductor position  406  on the temporary structure  112 . A first replacement conductor  300  is strung in to the position on the support structure  104  where the C phase conductor  102 C was located, in other words at the third conductor position  404 . 
       FIG.  51    depicts a transferring step  202  wherein the electrical load of the B phase conductor  102 B is transferred to the first replacement conductor  300  in the third conductor position  404 . The B phase conductor  102 B is replaced by a second replacement conductor  302 . At this step in this method, the electrical load of the C phase conductor  102 C is carried through the C phase conductor  102 C, which is supported on the fourth conductor position  406  by the temporary structure  112 . The electrical load of the B phase conductor  102 B is carried through the first replacement conductor  300  in the third conductor position  404 . 
       FIG.  52    depicts transferring step  204  wherein the electrical load of the A phase conductor  102 A is transferred to the second replacement conductor  302  in the second conductor position  402 . The A phase conductor  102 A is the replaced by a third replacement conductor  304 . 
       FIG.  53    depicts transferring step  206  wherein the electrical load on the second replacement conductor  302  is transferred to the third replacement conductor  304 . 
       FIG.  54    depicts transferring step  208  wherein the electrical load on the first replacement conductor  300  is transferred to the second replacement conductor  302 . 
       FIG.  55    depicts transferring step  210  wherein the electrical load from the C phase conductor  102 C is transferred to the first replacement conductor  404 . 
     During this method, the electrical load of the C phase is transferred from the third conductor position  404  to the fourth conductor position. The electrical load of the B phase is transferred from the second conductor position  402  to the third conductor position  404 . The electrical load of the A phase is transferred from the first conductor position  400  to the second conductor position  402 . Between each of these transfer steps, an old conductor is replaced with a new, replacement conductor wire. Then the steps are reversed with the electrical load of the A phase being transferred back to the first conductor position  400  from the second conductor position  402 , the electrical load of the B phase being transferred back to the second conductor position  402  from the third conductor position  404 , the electrical load of the C phase being transferred back to the third conductor position  404  from the fourth conductor position  406 . In this fashion illegal transpositions of the A, B and C phases are avoided while the electrical loads of the A, B and C phases are returned to their original conductor positions, now carried through new conductor lines  300 ,  302 ,  304 , as depicted in  FIG.  56   . 
     The various embodiments of the method of the invention described herein, temporarily relocating a phase conductor  102 , stringing a D phase conductor into place and using the D phase conductor to successively and in sequence transfer the electrical loads from proximate conductors, permits sections of new conductors, located between dead end junctures, to be strung one at a time. If it is desired to string new conductors along the entire length of a system  100 , or a length longer than practical for stringing conductors, then the re-conductoring methods are used for lengths that are practical and repeated along the length of the system until a desired length of new conductor is installed along the system. 
     It is appreciated by one skilled in the art, that in some power transfer systems  100 , more than one conductor  102  carries the power load for a particular phase. This may be done in instances when a power load is greater than a single-phase conductor can accommodate. In such cases, multiple (bundled) phase conductors  102  are often located next to each other and may hang from the same insulator  116  as shown in  FIG.  47   . The conductors may be separated by spacers  198 . Such bundle conductor systems  100  may be re-conductored in accordance with the invention by application of the procedures described herein to each conductor  102 . 
     While the above disclosure describes certain examples of the present invention, various changes, adaptations and modifications of the described examples will also be apparent to those skilled in the art. The scope of the claims should not be limited by the examples provided above; rather, the scope of the claims should be given the broadest interpretation that is consistent with the disclosure as a whole.