Patent Description:
Electric power transfer systems use one or more phases of conductors to transfer electric current within a grid. The conductors may be used for bulk transmission from a power generating plant to centers of high demand and for distribution within the centers of high demand. The conductors are supported above the ground by support structures, including towers, which are usually of metal lattice construction, and poles, which may be of wood, cement or steel (collectively referred to herein as support structures).

Over time one or more parts of the electric power transfer system may require maintenance or the installation of new equipment. For example, one or more sections of the conductors may require repair or replacement. One or more of the support towers may also require repair or replacement. Additionally, new equipment, such as sub-stations may be added to the system. For the safety of workers and equipment, the flow of electrical current is often shut off before maintenance, construction or other operations are performed.

Document <CIT> relates to HV power transfer system. In particular Fig.<NUM>-<NUM> disclose an electrical circuit breaker mounted on a boom. The device comprises a platform on which three insulators are disposed with their lower ends connected to the platform. Document <CIT> discloses a telescopic robotic arm for temporarily supporting energized power lines to enable repair or replacement of transmission poles. The robotic arm is connectible to the boom of a service vehicle and is operable by remote control.

According to the present invention, there is provided a boom mountable breaker system as claimed in claim <NUM>. According to the present invention, there is provided a method as claimed in claim <NUM>.

The present invention may allow for a safer and quicker interruption of electrical transmission by positioning the breaker proximal to the energized conductor. For example, electrical connection of the breaker to the energized conductor requires shorter lengths of conductive connecting wires, which are easier to handle safely in comparison to wires that extend to the surface below the energized conductor. Furthermore, shorter lengths of conductive connecting wires may be more easily handled in a safe manner when they are disconnected from the energized conductor.

Various examples of the apparatus are described in detail below, with reference to the accompanying drawings. The drawings may not be to scale and some features or elements of the depicted examples may purposely be embellished for clarity. Similar reference numbers within the drawings refer to similar or identical elements. The drawings are provided only as examples and, therefore, the drawings should be considered illustrative of the present invention and its various aspects, embodiments and options. The drawings should not be considered limiting or restrictive as to the scope of the invention.

<FIG> depicts an example support structure <NUM> that is used in an electric power transfer system <NUM>. The electric power transfer system <NUM> may comprise one or both of transmission systems or distribution systems. Support structures <NUM> may also be support poles, towers, pylons or other structures all of which are referred to herein collectively as support structures. The support structure <NUM> is depicted as comprising two support poles <NUM>, but this is not intended to be limiting. For example, the support structures <NUM> may comprise a single support pole, multiple support poles, latticed support towers or combinations thereof, as would be known to one skilled in the art. The support structure <NUM> has a cross arm <NUM> that supports an insulator or insulators <NUM> from which a conductor <NUM> is supported.

<FIG> depicts three phases of conductors <NUM>; namely, conductors 20A, 20B, and 20C. Each conductor <NUM> is supported by at least one corresponding insulator <NUM> and each conductor <NUM> may or may not be energized with flowing electric current and/or have a voltage potential. Energized conductors <NUM> may also be referred to as hot, live or electrified. While <FIG> depicts three phases of conductors <NUM>, this is not intended to be limiting, as there may be one, two, three, or more phases of conductors <NUM>. <FIG> also depicts the three phases as being spaced from one another in a horizontal plane with a single conductor <NUM> for each phase, this is not intended to be limiting. For example, the overhead power transfer system <NUM> may comprise phases that are spaced apart in a vertical or non-vertical plane and each phase may comprise multiple conductors <NUM>.

When the conductors <NUM> are energized the conductors <NUM> conduct high-voltage electricity (for example, above <NUM> kV or more) for bulk transmission of power from a power plant to both high demand sub-stations and rural sub-stations.

The support structure <NUM> may also include an upper portion <NUM> that supports one or more static lines <NUM>, which may also be referred to as optic lines or shielding lines. Typically, the static lines <NUM> are not energized. Rather, the static lines <NUM> provide protection from lighting strikes and, optionally, they may be or include fiber optic cables that are used to transfer optical signals.

<FIG> is a side elevation view of a section <NUM> of the electric power transfer system <NUM>. The section <NUM> is depicted, without intending to be limiting, as including two support structures 12A and 12B that support one or more conductors <NUM> and one or more static lines <NUM> therebetween. Support structures 12A and 12B may comprise the same features of one or more support poles <NUM>, a cross arm <NUM>, an insulator <NUM> and an upper portion <NUM>, or not. The section <NUM> may comprise one or more phases of conductors <NUM> and one or more static lines <NUM>.

Arrow "X" indicates the direction that electrical current is being transferred through the section <NUM>, from support structure 12A to support structure 12B. Electric current enters the section <NUM> first at an upstream end of the section <NUM> near to the support tower 12A and then exits the section <NUM> at a downstream end of the section <NUM>, which may be near the support tower 12B. The upstream end of the section <NUM> may also be referred to as the load end. The distance between the two support towers 12A, B may be in the order of tens of meters to hundreds or thousands of meters.

Often times it is desired to stop the flow of electric current through the section <NUM>. For example, maintenance operations may be required on the overhead power transfer system <NUM> at a portion that is downstream of the section <NUM> or it may be necessary to install new equipment downstream of the section <NUM>. Therefore, it is desirable to stop the flow of current for the safety of the line workers. Various embodiments of the present invention comprise the use of a circuit breaker to create an alternate circuit for the purpose of stopping the flow of current through the section <NUM>.

<FIG> depicts a step of connecting a jumper <NUM> to the conductor <NUM> within section <NUM>. The jumper <NUM>, which may also be referred to as a jumper line, and may be rated based upon the ability to conduct the entire current load that is flowing through the section <NUM>. In an alternative option, the jumper <NUM> may be rated to only conduct a portion of the entire current load that is flowing through the section <NUM> and more than one jumper <NUM> may be used. When installed, the jumper <NUM> is electrically connected to the conductor <NUM> to define a first alternate circuit <NUM>. The first alternate circuit <NUM> has an upstream end 28A and a downstream end 28B. Similarly, the jumper <NUM> has an upstream end 22A and a downstream end 22B. Typically the conductor <NUM> is energized and, therefore, the jumper <NUM> can be installed using hot sticks or other live-line techniques. In some instances, however, it may be that the conductor <NUM> is not energized, for whatever reason, when the jumper <NUM> is installed and live-line techniques may not be required, keeping in mind that live-line techniques may still be employed if the possibility exists of an induced voltage in the non-energized line. Using techniques known by those skilled in the art, the ends of jumper <NUM> may be removably installed across where it is desired to install an inline opener <NUM> in section <NUM> so that the jumper <NUM> may subsequently be detached from the conductor <NUM>. The length of jumper <NUM> may depend upon the physical characteristics of the section <NUM>, such as the distance and terrain between the support structures 12A, B. The length of jumper <NUM> may also depend upon the electrical characteristics of the section <NUM>, such as the current load and voltage within the section as would be known to one skilled in the art. The jumper <NUM> must be long enough to allow the installation of the insulated inline opener <NUM> seen in <FIG>. Jumper <NUM> is removably connected using conventional removable connectors such as bolted clamps, etc..

<FIG> shows a step of installing the insulated inline opener <NUM> on the conductor <NUM> between the upstream and downstream ends 22A, B of the jumper <NUM>. The insulated inline opener <NUM> may be made up of one or more dielectric materials such as, but not limited to, a polymer, a blend of multiple polymers, ceramic or a combination thereof. In a preferred embodiment the insulated inline opener <NUM> is a polymer insulator that prevents the transmission of current load within the section <NUM>.

When the inline opener <NUM> is installed on the conductor <NUM>, the entire current load flows through the first jumper <NUM> around the inline opener <NUM>, such as via the first alternate circuit <NUM>. In addition to providing the first alternate circuit <NUM>, the jumper <NUM> provides to a worker working in the section <NUM> a visual cue that the first alternate circuit <NUM> has been established.

At high voltages (for example, above <NUM> kV or more), due to arcing, it may be unsafe to merely disconnect the jumper <NUM> from the conductor <NUM> to interrupt current flow or transmission of current load through section <NUM>. Further, given sufficient high voltages, it may even be impossible to directly electrically disconnect the jumper <NUM> from the conductor <NUM> due to the arcing.

<FIG> depicts a step of positioning of a first breaker <NUM>, into the section <NUM>, proximal to the conductor <NUM>. It is understood that the first breaker <NUM> may be positioned below, and/or to the side, substantially level with, laterally of the conductor <NUM>, or adjacent combinations thereof. In a preferred embodiment, the first breaker <NUM> is positioned close, at a distance not less than the minimum approach distance (MAD), to the conductor <NUM>, so that long lengths of conductive connecting wire (such as for example would be required to reach a circuit breaker positioned on a truck or trailer) are not required to electrically connect the first breaker <NUM> to the conductor <NUM>. The MAD is well known to those skilled in the art.

The first breaker <NUM> is mounted on the distal end of a boom <NUM>, which provides a support for a breaker platform or base <NUM>, that in the illustrated embodiment not intended to be limiting, comprises a lower portion <NUM>, an upper portion <NUM> and a support base <NUM>. The boom <NUM> may be connected at one end of the lower portion <NUM> to a vehicle, such as a truck or trailer (not shown). In one embodiment, the boom <NUM> may be rotatably connected to the vehicle by a rotating pedestal or other known apparatus. The lower portion <NUM> may comprise one or more extendible and retractable sections that may be telescopically arranged with each other, for changing the axial length of the boom <NUM>. For example, the length of the lower portion <NUM> may increase or decrease along a longitudinal axis of the boom <NUM> (see broken line "Y" in <FIG>). The upper portion <NUM> may be connected to the lower portion <NUM>, opposite from the vehicle. Preferably, the upper portion <NUM> is made of, or coated in, a dielectric material. The dielectric material prevents electric current from being conducted along or through the upper portion <NUM>. Optionally, the upper portion <NUM> may also comprise extendible and retractable sections that move along the longitudinal axis of the boom <NUM>.

The support base <NUM> is connected to the distal end of the upper portion <NUM>, opposite to the lower portion <NUM>, for example by means of a boom adaptor 106a. The support base <NUM> is able to pivot into various positions relative to the longitudinal axis of the boom <NUM>. The first breaker <NUM> is mounted to the support base <NUM> so as to be upstanding therefrom.

The position of the boom <NUM> may be controlled remotely by an operator. For example, the position of the boom <NUM> relative to the vehicle can be changed, as can the axial length of the boom <NUM>. Furthermore, the operator can change the position of the support base <NUM> relative to the upper portion <NUM>. For example, the support base <NUM> may be rotated by a scissor linkage <NUM> mounted along boom adaptor 106a. The scissor linkage <NUM> may include one or more actuators 107a, whose actuation can be selectively controlled hydraulically, or otherwise, acting on the common hinged joint 107b between linkage members 107c, as would be known to one skilled in the art. As will also be appreciated by those skilled in the art, changing the position of the support base <NUM> relative to the upper portion <NUM> may be achieved by methods and means that are not limited to the scissor linkage <NUM>. For example, various other pivots, hinges, actuators, telescopic or sliding arrangements or combinations thereof may also be used.

Positioning of the boom <NUM> may be controlled by a control system (not shown) which may consist of a hydraulic system (not shown) having hydraulic hoses and valves. For example, the hydraulic system may fluidly connect an auxiliary hydraulic port of the vehicle, the lower portion <NUM> and the support base <NUM>. The control system may be remotely operated by means of digital radio signals, fiber optic cables, or other suitable insulated control means.

<CIT> "Boom-mountable Robotic Arm" and <CIT> entitled "Boom Mountable Robotic Arm" both describe booms that are suitable for use as the boom <NUM> in the present invention.

The first breaker <NUM> can be actuated between a closed position and an open position. When in the closed position the first breaker <NUM> comprises electrical contacts that are in direct contact with each other and can conduct the electric current that is flowing through the section <NUM> without generating unacceptable amounts of resistance or heat. When in the open position, the electrical contacts within the first breaker <NUM> are physically separated and any arcing therebetween has been suppressed so that the first breaker <NUM> acts as an electrical insulator that does not conduct electric current. Actuation of the first breaker <NUM> between the closed and open positions is controlled remotely, and may be manually controlled or it may be automatically controlled. In a preferred embodiment, actuation of the first breaker <NUM> is manually controlled remotely, as seen by way of example in <FIG>, by the operator to permit or stop the flow of current through the first breaker <NUM> as desired.

<FIG> and corresponding magnified views provided in <FIG> and <FIG> each depict one embodiment of the first breaker <NUM> that comprises a boom-mounted control box or housing <NUM>, a support insulator <NUM>, a breaking or breaker unit <NUM>, as used interchangeably herein, or interrupter, having terminals <NUM>, <NUM> at the ends thereof.

The boom-mounted control box or housing <NUM> contains an actuating mechanism (not shown) for actuating the first breaker <NUM> between the open and closed positions. For example, the actuating mechanism may be a single motion or a double motion design that may be selected from, but not limited to, the following: an energy storage mechanism, such as a spring; a driven mechanism, such as an electric motor, a hydraulic motor, a pneumatic-based mechanism; or combinations thereof.

The support insulator <NUM> insulates the breaking unit <NUM> and the terminals <NUM>, <NUM> from earth ground. The support insulator <NUM> may be a hollow body made of porcelain, or a dielectric composite, that may contain SF<NUM>.

The breaking unit <NUM> houses the electrical contacts of the first breaker <NUM> and the moving components that couple electrical contacts with the mechanism within the housing <NUM>. The breaking unit <NUM> may comprise an extinguishing mechanism for extinguishing any arcing between the electrical contacts when the first breaker <NUM> is actuated to the open position. For example, the extinguishing mechanism may be a SF<NUM> puffer design, a SF<NUM> self-blast design or other types of known extinguishing mechanisms. In one embodiment, the breaking unit <NUM> comprises an upstream breaking portion <NUM> and a downstream breaking portion <NUM>. Optionally, the upstream and downstream breaking portions <NUM>, <NUM> are substantially co-axially aligned with each other along a common longitudinal axis (shown as broken line "Z" in <FIG>) that is substantially perpendicular to the support insulator <NUM>. This embodiment of the first breaker <NUM> may also be referred to as a "T breaker". Each of the breaking portions <NUM>, <NUM> are made of porcelain, or a composite material, and filled with pressurized SF<NUM> gas. Because the terminals <NUM>, <NUM> are positioned on either end of the breaking unit <NUM>, the breaking unit <NUM> can become live and subject to voltage and current when the first breaker <NUM> is closed and electrically connected with the conductor <NUM>.

<FIG> depicts a step of electrically connecting the first breaker <NUM> to the conductor <NUM>. This step is preceded by a step of confirming that the first breaker is in the open position. In <FIG>, the first breaker <NUM> is in an open position and it does not conduct electric current. A conductive connection jumper or wire <NUM> is connected to the upstream terminal <NUM> of the first breaker <NUM> and to the conductor <NUM>, upstream of the upstream end 22A of the jumper <NUM>. Another conductive connection jumper cable or wire <NUM> is connected to the downstream terminal <NUM> and the conductor <NUM>, downstream of the downstream end 22B of the jumper <NUM>. The conductive connection wires <NUM>, <NUM> may also be rated to handle the voltage and current load within the section <NUM>. For example, the gauge of conductive connection wires <NUM>, <NUM> may be the same as the jumper <NUM>.

<FIG> depicts a step of actuating the first breaker <NUM> to the closed position. In the closed position, electric current can be conducted through the first breaker <NUM>. Together, the conductive connection wires <NUM>, <NUM> and the first breaker <NUM> define a second alternate circuit <NUM>. The second alternate circuit <NUM> has an upstream end 128A and a downstream end 128B. The second alternate circuit <NUM> is parallel to the first alternate circuit <NUM> and thus at least a portion of the current load in the system <NUM> diverts through the second alternate circuit and around the first alternate circuit <NUM> and the inline opener <NUM>.

<FIG> depicts a step of disconnecting the jumper <NUM> from the conductor <NUM> so that the current load within the section <NUM> flows through the second alternate circuit <NUM>. <FIG> depicts a step of actuating the first breaker <NUM> back into the open position. This step generates a de-energized portion <NUM> of the conductor <NUM> that is downstream of the first breaker <NUM>. <FIG> depicts a step of disconnecting the conductive connection wires <NUM>, <NUM> from the conductor <NUM> and moving the first breaker <NUM> into a position that is away from the conductor <NUM>. For example as illustrated the first breaker <NUM> may be moved completely away from section <NUM>.

The first breaker <NUM> is rated to meet the voltage and current specifications of the system <NUM>. In one embodiment, the first breaker <NUM> is selected from known circuit breakers such as, but not limited to, magnetic breakers, thermal magnetic breakers, and live tank breakers, such as sulfur hexafluoride (SF<NUM>) breakers all of which provide intentional actuation between the open and closed positions, as would be appreciated by one skilled in the art. As seen in <FIG> by way of example, a power cord 108a runs through travellers 108e on the boom <NUM> from the actuating mechanism in boom-mounted control box <NUM> to a circuit breaker open/close control box 108b at the ground level. The control box 108b may for example be mounted on a support truck (not shown). Another power cord 108c runs between the circuit breaker open/close control box 108b and a generator 108d similarly located on or near the ground level, for example on the support truck, etc..

<FIG> depicts another embodiment of the present invention that utilizes a second breaker <NUM>, better seen in <FIG>, instead of the first breaker <NUM>. <FIG> depicts the section <NUM> with the same features described above regarding <FIG> with the difference between <FIG> and <FIG> being the use of the second breaker <NUM>. <FIG> depicts the second breaker <NUM> mounted on the support base <NUM> upon the boom <NUM>. The second breaker <NUM> can be actuated between a closed position and an open position. When in the closed position the first breaker <NUM> comprises electrical contacts that are in direct contact with each other and can conduct the electric current that is flowing through the section <NUM> without generating unacceptable amounts of resistance or heat. When in the open position, the electrical contacts within the second breaker <NUM> are physically separated and any arcing therebetween has been suppressed so that the second breaker <NUM> acts as an electrical insulator that does not conduct electric current.

One embodiment of the second breaker <NUM>, which is shown in a corresponding magnified view in <FIG>, comprises a housing <NUM>, a support insulator <NUM>, a breaking unit <NUM> with a primary terminal <NUM>, <NUM> at each end of the breaking unit <NUM> (see <FIG>). This embodiment of the second breaker <NUM> may also be referred to as an "I breaker". The features of the second breaker <NUM> perform the same functions as those described above regarding the first breaker <NUM>. For example, the housing <NUM> houses a mechanism for actuating the second breaker <NUM> between the open and closed positions. The support insulator <NUM> insulates the breaking unit <NUM> from ground. The breaking unit <NUM> houses the electrical contacts and the mechanical components that couple the electrical contacts with the mechanism within the housing <NUM>. As with the breaking unit <NUM>, the breaking unit <NUM> may comprise an extinguishing mechanism for extinguishing any arcing between the electrical contacts when the second breaker <NUM> is actuated to the open position. For example, the extinguishing mechanism may be a SF<NUM> puffer design, a SF<NUM> self-blast design or other types of known extinguishing mechanisms.

As depicted in <FIG>, the second breaker <NUM> is electrically connected to the conductor <NUM> on either side of the jumper <NUM> by conductive connection wires <NUM>, <NUM>. The second breaker <NUM> is in the open position in <FIG>.

<FIG> depicts a step of actuating the second breaker <NUM> to the closed position, which creates a third alternate circuit <NUM>. The third alternate circuit <NUM> has an upstream end 228A and a downstream end 228B. The third alternate circuit <NUM> is parallel to the first alternate circuit <NUM> and a portion of the current load in the system <NUM> diverts around the first alternate circuit <NUM> and the inline opener <NUM>.

<FIG> depicts a step of disconnecting the jumper <NUM> from the conductor <NUM>. The second breaker <NUM> is still in the closed position so that the current load within the section <NUM> flows through the third alternate circuit <NUM>.

<FIG> depicts a step of actuating the second breaker <NUM> to the open position. This stops the conduction of the current load through the second breaker <NUM> resulting in the de-energized portion <NUM> of the conductor <NUM> downstream of the second breaker <NUM>. As described above regarding the first breaker <NUM>, the second breaker can then be disconnected from the conductor <NUM> and moved to a position that is away from the conductor <NUM>. This leaves the section <NUM> with a portion of live conductor <NUM> and a de-energized portion <NUM>.

Claim 1:
A boom mountable breaker system for mounting on the distal end of a boom comprising:
a. a boom adaptor (106A) mountable onto the distal end of the boom (<NUM>);
b. a platform (<NUM>) pivotally mounted onto the boom adaptor (106A);
c. a selectively actuable actuator (107A) mounted to, so as to cooperate between, the boom adaptor (106A) and the platform (<NUM>), whereby actuation of the actuator (107A) selectively pivots the platform relative to the boom adaptor;
d. a selectively operable electrical circuit breaker (<NUM>) mounted on, so as to be electrically insulated and upstanding from, the platform (<NUM>) wherein the electrical circuit breaker (<NUM>) includes an upstanding, electrically insulating lower insulator (<NUM>) having opposite upper and lower ends, and at least one electrically insulating upper insulator (<NUM>,<NUM>) having spaced apart upstream and downstream electrical connectors thereon, wherein the electrical connectors are configured for mounting of electrically conductive cables thereto, and wherein the at least one electrically insulating upper insulator has a circuit breaker unit mounted therein, and wherein the upper insulator (<NUM>,<NUM>) is mounted to the upper end of the lower insulator (<NUM>), and the lower end of the lower insulator (<NUM>) is mounted to the platform (<NUM>);
e. a breaker control mounted on the platform (<NUM>) between the lower end of the lower insulator (<NUM>) and the platform (<NUM>), the breaker control (<NUM>) configured to selectively open and close the electrical circuit breaker (<NUM>), wherein the breaker control includes a housing (<NUM>).