CA1163689A - Roller expansion joint - Google Patents
Roller expansion jointInfo
- Publication number
- CA1163689A CA1163689A CA000401761A CA401761A CA1163689A CA 1163689 A CA1163689 A CA 1163689A CA 000401761 A CA000401761 A CA 000401761A CA 401761 A CA401761 A CA 401761A CA 1163689 A CA1163689 A CA 1163689A
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- CA
- Canada
- Prior art keywords
- conductor
- roller
- segment
- expansion
- affixation
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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Abstract
ROLLER EXPANSION JOINT
ABSTRACT OF THE DISCLOSURE
A roller expansion joint for enabling longitudinal changes of dimension within a current carrying conduc-tor, relative to the ends of the conductor. The roller expansion joint comprises an electrically conductive expansion loop for affixation to an end of the conductor and roller means for rollably supporting the conductor.
ABSTRACT OF THE DISCLOSURE
A roller expansion joint for enabling longitudinal changes of dimension within a current carrying conduc-tor, relative to the ends of the conductor. The roller expansion joint comprises an electrically conductive expansion loop for affixation to an end of the conductor and roller means for rollably supporting the conductor.
Description
li~3~9 ROLLER EXPANSION JOINT
Field of the Invention This invention relates to support structures for current carrying conductors and to expansion joints for enabling longitudinal changes of dimension within the conductor and movement of the conductor relative to other objects, without affecting the conductor's current carrying capability. The roller expansion joint of the present invention includes an electrically conductive, flexible expansion loop for affixation to an end of the conductor and roller means for rollably supporting the conductor as it moves.
~ e _ nd of the Invention Current carrying conductors are often subject to thermal expansion and contraction caused by changes in ambient temperature, by changes in heat generated within the conductor by load currents, or by radiant energy imparted to the cGnductor by the sun or other en-ergy sources. Such expansion or contraction may cause longitudinal movement of the conductor relative to the ends of the conductor which are typically connected to electrical apparatus. Longitudinal movement of a con-ductor such as a high voltage electric power bus bar may also be caused by the weight of foreign material such as ; ~ ice which may adhere to the conductor. If no compensa-tion for such movement is provided, the conductor may break or pull away from a point of connection, inter-rupt1ng the transmission of electric current by the conductor. It has been found, for example, that a high voltage electric power bus bar exposed to typical outdoor conditions encountered in the Province of Saskatchewan, Canada, may be subject in an average year to expansion or contraction of as much as 4 inches (lO0 mm.) over every lO0 feet (30 m.) of its length. Simi-larly, relatively low voltage current carrying conduc-tors such as those used to power electric arc furnaces may be subject to significant thermal expansion or con-traction, at least in the immediate vicinity of the furnace.
In situations where conductor expansion or contraction is expected, expansion joints are typically inserted at regular intervals in the current carrying conductor to enable the conductor to expand or contract without stretching beyond its tensile capacity, without permitting excessive sagging of the conductor, and with-out stressing components to which the conductor may be connected.
Conventional conductor expansion joints have suffered from a number of disadvantages. Typically, conventional conductor expansion joints enable limited sliding movement of a conductor segment relative to a fixed support. However, frictional forces at the point of sliding contact frequently result in jamming which disables the expansion joint.
; Another disadvantage of conventional conductor expansion joints is the widespread use of compression connections ln which parts are compressed together to form a connection by using elements such as bolts.
Bol~ed connec~ions are unreliable because they tend to ~ 2 --i89 loosen and reduce the current-carrying capacity of the expansion joint. ~olted connections also have inter-stices which may be contaminated by dirt buildup or cor-rosion, inhibiting the ability to pass electric current across the bolted connections.
A further disadvantage o conventional expan-sion joints has been the use of expansion joint compo-nents which are formed of a different metal than that used to form the conductor. This use of dissimilar met-als results in galvanic action and consequent electroly-tic corrosion at the point of connection between the conductor and the expansion joint which, again, reduces the current-carrying capacity of the expansion joint.
~ the Invention The invention is directed to an expansion joint for enabling longitudinal changes of dimension within a current carrying conductor. The expansion joint comprises an electrically conductive expansion loop for affixation to an end of the conductor and rol-ler means for rollably supporting the conductor. The expansion loop comprises a plurality of spaced-apart l m inations. The roller means comprises a pair of rol-lers for positioning adjacent vertically opposed sides of the conductor for rollably supporting the conductor.
The rollers substantially reduce frictional forces at the point of;contact with the conductor, thus minimizing -the potential for jamming of the expansion jaint.
The expansion loop may include a first end for affixation to an end of the conductor and a second end ~: :
~ 30~ for rigid terminal connection. Alternatively, the :::
~ - 3 -- .
:
::
11~36~g expansion loop may include a first end for aEixation to an end of a first conductor segment and a second end for affixation to an end of a second conductor segment.
Preferably, the expansion loop is welded to the conductor ends and is formed of the same material as the conductor. Welded connections are less likely to work loose as the conductor moves than compression con-nections. By forming the expansion joint of the same material as the conductor, the potential for electro-lytic corrosion is reduced.
Advantageously, a conductor extension memberis affixed between the conductor end and the expansion loop end to simplify on-site welding of the expansion joint to a conductor segment.
In a preferred embodiment, adjacent lamina-tions of the expansion loop are spaced apart by at least 1.6 mm. "
The invention also provides a roller support for an electrical conductor, the support comprising a pair of rollers for positioning adjacent vertically opposed sides of the conductor for rollably supporting the conductor.
t~ _ I tb~ De~ ol~
FIGURE 1 is a side elevation view of a roller :
: ~ :
expansion joint for connection between a current carry-ing conductor and a piece of normally immovable equip-ment.
FIGURE 2 is a sectional view taken with res-pect to section line 2-2 of FIGURE 1.
~: :
~ 4 -il63685 FIGURE 3 is a top plan view of the base plate 24 showing the holes provided for bolted connection thereof to a piece of terminal equipment.
FIGURE 4 is a side elevation view of a roller S expansion joint for connection between adjacent long-itudinally aligned conductor segments.
Detailed Descri~tion of Three Embodiments of the Invention The preferred embodiments to be described con-template roller expansion joints and roller support structures for a high voltage electric power bus bar.
However, it is not intended that the invention be limit-ed to high voltage applications. It is expected that the invention may alleviate problems caused by conductor expansion or contraction in a wide range of applications including, for example, conductors for powering electric arc furnaces or electroplating apparatus - either of which may be subject to significant thermal expansion or contraction in the vicinity of the powered apparatus.
One of two different roller expansion joint constructions may be selected depending upon the indi-vidual application. The two types of roller expansion joints are herein referred to as the "single roller ex-pansion joint" and the "double roller expansion jointn;
the principal difference between the two types being the number of roller pairs provided. The single roller ~; expansion joint is used where a conductor segment is to be connected to a rigid terminal point. The double roller expansion joint is used to interconnect two long-itudinally aligned conductor segments. The roller sup-port structure may also be used separately from the 11636~
expansion joint elements to support a conductor segment at points where allowance for longitudinal movement need not be made.
Single R lle E pansion J_ nt Figure 1 depicts a single roller expansion joint. The single roller expansion joint includes an electrically conductive expansion loop 10 which compris-es a plurality of spaced-apart laminations. Expansion loop 10 has a first end 12 for affixation to an end of a conductor extension member such as stub connector 20, and a second end 16 for affixation to base plate 24.
Base plate 24 may then be bolted to a piece of normally immovable equipment such as a disconnect switch (not shown).
Conductor 14 is circumferentially welded at 18 to stub conductor 20. Conductor 14 will typically com-prise a section of aluminium pipe (such as Alcan B505~
aluminium alloy conductor pipe) in which case stub con-nector 20 may comprise a short length of the same pipe.
An insert 22 comprising a short length of pipe having an outside diameter slightly less than the inside diameter of either conductor 14 or stub connector 20 is placed inside conductor 14 and stub connector 20 to overlap welded connection 18, providing rigidity at the point of connection.
Base plate 24 supports a pair of roller brac-kets 26 which extend vertically upward from base plate ~ ~, 24 ad~acent opposite sides of stub connector 20 (best seen in Flgure 2). Roller brackets 26 are drilled to provide relatively loose support for rollers 28 which li63~39 are positioned adjacent vertically opposed sides of stub connector 20 to rollably support stub connector 20.
The ends of rollers 28 which are fitted within roller brackets 26 should be coated with a suitable lubricant such as MOLYKOTE~ 321R, a product of Dow Corning.
A first pair of backing plates 30 are welded together around their outer edges to sandwich the lamin-ations comprising expansion loop first end 12. Backing plates 30 provide reinforcement and enable welded con-nection of expansion loop first end 12 to stub connector 20. Advantageously, stub connector 20 is welded to backing plate 30 in a production environment before the expansion joint is welded to a conductor segment in the field. Stub connector 20 protrudes from the roller ex-pansion joint and facilitates relatively simple on-site welding of the expansion joint to a conductor segment.
A second pair of backing plates 30 sandwich expansion loop second end 16 to provide reinforcement and to `~
facilitate welded connection of expansion loop second end 16 to base plate 24. Base plate 24 is then con-nected (by means of bolts - not shown) to whatever terminal equipment may be provided. The bolts are passed through holes 23 in base plate 24 (best seen in Figure 3).
A guide means such as a pair of guide plates 32 is welded to rol~ler brackets 26 to prevent rotational movement of conductor 14 if it is used in conjunction with a rotating stack device of the type commonly found in electric power line disconnect switches. Figure 1 shows only a single guide plate 32. In practice, guide `` 1163~9 plates are provided in pairs, as shown in Figure 2, on opposite sides of stub connector 20, one guide plate being welded to each of the roller brackets 26. Without a suitable yuide means, operation of the disconnect switch may impart a torque to the conductor, causing it to rotate and possibly misaligning the conductor and/or subjecting it to undesirable stresses which may cause physical damage to the conductor or to equipment connected to the conductor. `
Preferably, all sharp edges and welds on all components of the expansion joint assembly are ground smooth to limit undesirable corona discharge. Inso-far as practically possible all expansion joint compon-ents should be constructed of the same material as con-ductor 14 to eliminate the possibilty of electrolytic corrosion at points of contact between dissimilar met-als. Welded connections should be used in preference to -compression (bolted) connections since compression con-nections are subject to contamination by dirt buildup or corrosion and may tend to loosen, thus reducing the current carrying capacity of the expansion joint.
The single roller expansion joint is normally supported on an insulated terminal pad. As conductor 14 expands or contracts it forces stub connector 20 to move to either the right or the left as viewed in FIGURE 1.
Stub~connector 20 rolls across rollers 28 which may rotate, using the holes drilled in roller brackets 26 as bearing surfaces. The laminations comprising expansion loop 10 flex as stub connector 20 moves to the right or to the left, enabling continuous electrical conductivity ::
11~i3~i~9 between conductor 14 and the terminal e~uipment (not shown) to which it is connected via the expansion joint.
It has been found that an expansion loop suit-able for use with a 1200 ampere current carrying conduc-tor constructed of 3-inch inside diameter aluminium pipe may be fabricated from ten aluminium laminations, each measuring .032" in thickness. Preferably, adjacent laminations included in such an expansion loop are spaced apart by about 1/1~" to prevent binding or jam-ming as the loop flexes. Temporary spacers may beplaced between adjacent laminations to hold them apart while the laminations are welded in place between back-ing plates 30. The loop radius "R" (see Figure 1) in such an expansion loop is preferably at least 2 3/4" (70 mm.) so that loop 10 has ample capacity for flexing to absorb expansion or contraction of the conductor.
Double Roller Expansion Joint FIGURE 4 depicts a double roller expansion joint. The double roller expansion joint provides an electrically conductive expansion loop 33 for affixation between a first conductor segment 34 and a second con-ductor segment 36. An end of first conductor segment 34 is circumferentially welded to a first extension member such as stub connector 38 which is rollably supported by rollers 40 positioned adjacent vertically opposed sides of stub connector 38. Rollers 40 are rotatably supported by a pair of roller brackets 42 (only one of which is visible in FIGURE 4). A first end 44 of expansion loop 33 is welded to stub connector 38.
The right hand half of the double roller expansion - g _ 11~36~9 joint depicted in FIGURE 4 is identical to the left hand portion just described. A second roller pair 46 pro-vides rolling support for a second conductor extension member such as stub connector 48 which is circumferen-tially welded to an end of second conductor segment 36.Rollers 46 are rotatably supported by a pair of roller brackets 50 (only one of which is visible in FIGURE 3).
A second end 52 of expansion loop 33 is welded to stub connector 48. Roller pairs 40 and 46 provide rolling support for conductor segments 34 and 36 respectively as they move to either the right or the left as viewed in FIGURE 4. The laminations comprising expansion loop 33 flex to maintain electrical conductivity between conduc-tor segments 34 and 36 as the segments move relative to one another.
Installation The spacing between consecutive expansion joints will depend in most cases on the bus bar configu-ration. In general, however, no segment of a high vol-tage electric power bus bar should be fixed at both endswithout inaluding an expansion joint to allow for expan-sion and contraction of the bus bar. In bus bar seg-ments one might expect to employ an expansion joint every 50 feet (15 m.) along the bus bar. This, however, is a matter of judgment and will vary depending on the expected range of temperatures to which the bus bar will be subjected.
~; ~ When either single or double roller expansion joints are installed in electric power bus bar, they must be adjusted relative to ambient temperature 1~63689 conditions to ensure proper absorption of conductor expansion or contraction. The expansion joints are adjusted by varying the displacement "D" shown in FIGURES 1 and 4 respectively. Note that displacement "D" for a single roller expansion joint is the distance between opposed backing plates 30 whereas the displacement "D" for a double roller expansion joint is one-half this distance. For Alcan B505~ aluminium alloy conductor pipe, "D" is computed according to the formula:
D = 1/2 + L(12)~.000023)~0C - TC) where:
D = expansion joint adjustment displacement, mea-sured in inches L = the length of the conductor segment which the expansion joint is to enable to expand or con-tract. If the conductor segment is rigidly fixed at one end, then one expansion joint must absorb expansion or contraction along the entire length "L~ of the segment. Otherwise, if expansion joints are provided at both ends of the conductor segment, then each expansion joint need absorb only expansions or contrac-tions expected along 1/2 of the length "L" of the conductor segment.
T = the ambient bus bar temperature at the time of installation of the expansion joint. ~-For a single roller expansion joint used with Alcan B505~ 3-inch inside diameter aluminium alloy con-ductor pipe, "D" should be no greater than 3n. For a g double roller expansion joint used with the same conduc-tor pipe, "D" should be a maximum of 2".
Conductor Se ~ent Roller S~ t Structure Base plate 24, roller brackets 26 and rollers 28 may be used separately from the expansion joint elements to support a conductor segment at points where allowance or longitudinal movement need not be made.
For example, it may be convenient to mount base plate 24, roller bracket 26 and rollers 28 at the top of an insulator stack to rollably support a conductor segment between the rollers at the top of the insulator stack.
As will be apparent to those skilled in the art in the light of the foregoing disclosure, many alterations and modifications are possible in the practice of this invention without departing from the spirit or scope thereof. Accordingly, the scope of the invention is to be construed in accordance with the substance defined by the following claims.
Field of the Invention This invention relates to support structures for current carrying conductors and to expansion joints for enabling longitudinal changes of dimension within the conductor and movement of the conductor relative to other objects, without affecting the conductor's current carrying capability. The roller expansion joint of the present invention includes an electrically conductive, flexible expansion loop for affixation to an end of the conductor and roller means for rollably supporting the conductor as it moves.
~ e _ nd of the Invention Current carrying conductors are often subject to thermal expansion and contraction caused by changes in ambient temperature, by changes in heat generated within the conductor by load currents, or by radiant energy imparted to the cGnductor by the sun or other en-ergy sources. Such expansion or contraction may cause longitudinal movement of the conductor relative to the ends of the conductor which are typically connected to electrical apparatus. Longitudinal movement of a con-ductor such as a high voltage electric power bus bar may also be caused by the weight of foreign material such as ; ~ ice which may adhere to the conductor. If no compensa-tion for such movement is provided, the conductor may break or pull away from a point of connection, inter-rupt1ng the transmission of electric current by the conductor. It has been found, for example, that a high voltage electric power bus bar exposed to typical outdoor conditions encountered in the Province of Saskatchewan, Canada, may be subject in an average year to expansion or contraction of as much as 4 inches (lO0 mm.) over every lO0 feet (30 m.) of its length. Simi-larly, relatively low voltage current carrying conduc-tors such as those used to power electric arc furnaces may be subject to significant thermal expansion or con-traction, at least in the immediate vicinity of the furnace.
In situations where conductor expansion or contraction is expected, expansion joints are typically inserted at regular intervals in the current carrying conductor to enable the conductor to expand or contract without stretching beyond its tensile capacity, without permitting excessive sagging of the conductor, and with-out stressing components to which the conductor may be connected.
Conventional conductor expansion joints have suffered from a number of disadvantages. Typically, conventional conductor expansion joints enable limited sliding movement of a conductor segment relative to a fixed support. However, frictional forces at the point of sliding contact frequently result in jamming which disables the expansion joint.
; Another disadvantage of conventional conductor expansion joints is the widespread use of compression connections ln which parts are compressed together to form a connection by using elements such as bolts.
Bol~ed connec~ions are unreliable because they tend to ~ 2 --i89 loosen and reduce the current-carrying capacity of the expansion joint. ~olted connections also have inter-stices which may be contaminated by dirt buildup or cor-rosion, inhibiting the ability to pass electric current across the bolted connections.
A further disadvantage o conventional expan-sion joints has been the use of expansion joint compo-nents which are formed of a different metal than that used to form the conductor. This use of dissimilar met-als results in galvanic action and consequent electroly-tic corrosion at the point of connection between the conductor and the expansion joint which, again, reduces the current-carrying capacity of the expansion joint.
~ the Invention The invention is directed to an expansion joint for enabling longitudinal changes of dimension within a current carrying conductor. The expansion joint comprises an electrically conductive expansion loop for affixation to an end of the conductor and rol-ler means for rollably supporting the conductor. The expansion loop comprises a plurality of spaced-apart l m inations. The roller means comprises a pair of rol-lers for positioning adjacent vertically opposed sides of the conductor for rollably supporting the conductor.
The rollers substantially reduce frictional forces at the point of;contact with the conductor, thus minimizing -the potential for jamming of the expansion jaint.
The expansion loop may include a first end for affixation to an end of the conductor and a second end ~: :
~ 30~ for rigid terminal connection. Alternatively, the :::
~ - 3 -- .
:
::
11~36~g expansion loop may include a first end for aEixation to an end of a first conductor segment and a second end for affixation to an end of a second conductor segment.
Preferably, the expansion loop is welded to the conductor ends and is formed of the same material as the conductor. Welded connections are less likely to work loose as the conductor moves than compression con-nections. By forming the expansion joint of the same material as the conductor, the potential for electro-lytic corrosion is reduced.
Advantageously, a conductor extension memberis affixed between the conductor end and the expansion loop end to simplify on-site welding of the expansion joint to a conductor segment.
In a preferred embodiment, adjacent lamina-tions of the expansion loop are spaced apart by at least 1.6 mm. "
The invention also provides a roller support for an electrical conductor, the support comprising a pair of rollers for positioning adjacent vertically opposed sides of the conductor for rollably supporting the conductor.
t~ _ I tb~ De~ ol~
FIGURE 1 is a side elevation view of a roller :
: ~ :
expansion joint for connection between a current carry-ing conductor and a piece of normally immovable equip-ment.
FIGURE 2 is a sectional view taken with res-pect to section line 2-2 of FIGURE 1.
~: :
~ 4 -il63685 FIGURE 3 is a top plan view of the base plate 24 showing the holes provided for bolted connection thereof to a piece of terminal equipment.
FIGURE 4 is a side elevation view of a roller S expansion joint for connection between adjacent long-itudinally aligned conductor segments.
Detailed Descri~tion of Three Embodiments of the Invention The preferred embodiments to be described con-template roller expansion joints and roller support structures for a high voltage electric power bus bar.
However, it is not intended that the invention be limit-ed to high voltage applications. It is expected that the invention may alleviate problems caused by conductor expansion or contraction in a wide range of applications including, for example, conductors for powering electric arc furnaces or electroplating apparatus - either of which may be subject to significant thermal expansion or contraction in the vicinity of the powered apparatus.
One of two different roller expansion joint constructions may be selected depending upon the indi-vidual application. The two types of roller expansion joints are herein referred to as the "single roller ex-pansion joint" and the "double roller expansion jointn;
the principal difference between the two types being the number of roller pairs provided. The single roller ~; expansion joint is used where a conductor segment is to be connected to a rigid terminal point. The double roller expansion joint is used to interconnect two long-itudinally aligned conductor segments. The roller sup-port structure may also be used separately from the 11636~
expansion joint elements to support a conductor segment at points where allowance for longitudinal movement need not be made.
Single R lle E pansion J_ nt Figure 1 depicts a single roller expansion joint. The single roller expansion joint includes an electrically conductive expansion loop 10 which compris-es a plurality of spaced-apart laminations. Expansion loop 10 has a first end 12 for affixation to an end of a conductor extension member such as stub connector 20, and a second end 16 for affixation to base plate 24.
Base plate 24 may then be bolted to a piece of normally immovable equipment such as a disconnect switch (not shown).
Conductor 14 is circumferentially welded at 18 to stub conductor 20. Conductor 14 will typically com-prise a section of aluminium pipe (such as Alcan B505~
aluminium alloy conductor pipe) in which case stub con-nector 20 may comprise a short length of the same pipe.
An insert 22 comprising a short length of pipe having an outside diameter slightly less than the inside diameter of either conductor 14 or stub connector 20 is placed inside conductor 14 and stub connector 20 to overlap welded connection 18, providing rigidity at the point of connection.
Base plate 24 supports a pair of roller brac-kets 26 which extend vertically upward from base plate ~ ~, 24 ad~acent opposite sides of stub connector 20 (best seen in Flgure 2). Roller brackets 26 are drilled to provide relatively loose support for rollers 28 which li63~39 are positioned adjacent vertically opposed sides of stub connector 20 to rollably support stub connector 20.
The ends of rollers 28 which are fitted within roller brackets 26 should be coated with a suitable lubricant such as MOLYKOTE~ 321R, a product of Dow Corning.
A first pair of backing plates 30 are welded together around their outer edges to sandwich the lamin-ations comprising expansion loop first end 12. Backing plates 30 provide reinforcement and enable welded con-nection of expansion loop first end 12 to stub connector 20. Advantageously, stub connector 20 is welded to backing plate 30 in a production environment before the expansion joint is welded to a conductor segment in the field. Stub connector 20 protrudes from the roller ex-pansion joint and facilitates relatively simple on-site welding of the expansion joint to a conductor segment.
A second pair of backing plates 30 sandwich expansion loop second end 16 to provide reinforcement and to `~
facilitate welded connection of expansion loop second end 16 to base plate 24. Base plate 24 is then con-nected (by means of bolts - not shown) to whatever terminal equipment may be provided. The bolts are passed through holes 23 in base plate 24 (best seen in Figure 3).
A guide means such as a pair of guide plates 32 is welded to rol~ler brackets 26 to prevent rotational movement of conductor 14 if it is used in conjunction with a rotating stack device of the type commonly found in electric power line disconnect switches. Figure 1 shows only a single guide plate 32. In practice, guide `` 1163~9 plates are provided in pairs, as shown in Figure 2, on opposite sides of stub connector 20, one guide plate being welded to each of the roller brackets 26. Without a suitable yuide means, operation of the disconnect switch may impart a torque to the conductor, causing it to rotate and possibly misaligning the conductor and/or subjecting it to undesirable stresses which may cause physical damage to the conductor or to equipment connected to the conductor. `
Preferably, all sharp edges and welds on all components of the expansion joint assembly are ground smooth to limit undesirable corona discharge. Inso-far as practically possible all expansion joint compon-ents should be constructed of the same material as con-ductor 14 to eliminate the possibilty of electrolytic corrosion at points of contact between dissimilar met-als. Welded connections should be used in preference to -compression (bolted) connections since compression con-nections are subject to contamination by dirt buildup or corrosion and may tend to loosen, thus reducing the current carrying capacity of the expansion joint.
The single roller expansion joint is normally supported on an insulated terminal pad. As conductor 14 expands or contracts it forces stub connector 20 to move to either the right or the left as viewed in FIGURE 1.
Stub~connector 20 rolls across rollers 28 which may rotate, using the holes drilled in roller brackets 26 as bearing surfaces. The laminations comprising expansion loop 10 flex as stub connector 20 moves to the right or to the left, enabling continuous electrical conductivity ::
11~i3~i~9 between conductor 14 and the terminal e~uipment (not shown) to which it is connected via the expansion joint.
It has been found that an expansion loop suit-able for use with a 1200 ampere current carrying conduc-tor constructed of 3-inch inside diameter aluminium pipe may be fabricated from ten aluminium laminations, each measuring .032" in thickness. Preferably, adjacent laminations included in such an expansion loop are spaced apart by about 1/1~" to prevent binding or jam-ming as the loop flexes. Temporary spacers may beplaced between adjacent laminations to hold them apart while the laminations are welded in place between back-ing plates 30. The loop radius "R" (see Figure 1) in such an expansion loop is preferably at least 2 3/4" (70 mm.) so that loop 10 has ample capacity for flexing to absorb expansion or contraction of the conductor.
Double Roller Expansion Joint FIGURE 4 depicts a double roller expansion joint. The double roller expansion joint provides an electrically conductive expansion loop 33 for affixation between a first conductor segment 34 and a second con-ductor segment 36. An end of first conductor segment 34 is circumferentially welded to a first extension member such as stub connector 38 which is rollably supported by rollers 40 positioned adjacent vertically opposed sides of stub connector 38. Rollers 40 are rotatably supported by a pair of roller brackets 42 (only one of which is visible in FIGURE 4). A first end 44 of expansion loop 33 is welded to stub connector 38.
The right hand half of the double roller expansion - g _ 11~36~9 joint depicted in FIGURE 4 is identical to the left hand portion just described. A second roller pair 46 pro-vides rolling support for a second conductor extension member such as stub connector 48 which is circumferen-tially welded to an end of second conductor segment 36.Rollers 46 are rotatably supported by a pair of roller brackets 50 (only one of which is visible in FIGURE 3).
A second end 52 of expansion loop 33 is welded to stub connector 48. Roller pairs 40 and 46 provide rolling support for conductor segments 34 and 36 respectively as they move to either the right or the left as viewed in FIGURE 4. The laminations comprising expansion loop 33 flex to maintain electrical conductivity between conduc-tor segments 34 and 36 as the segments move relative to one another.
Installation The spacing between consecutive expansion joints will depend in most cases on the bus bar configu-ration. In general, however, no segment of a high vol-tage electric power bus bar should be fixed at both endswithout inaluding an expansion joint to allow for expan-sion and contraction of the bus bar. In bus bar seg-ments one might expect to employ an expansion joint every 50 feet (15 m.) along the bus bar. This, however, is a matter of judgment and will vary depending on the expected range of temperatures to which the bus bar will be subjected.
~; ~ When either single or double roller expansion joints are installed in electric power bus bar, they must be adjusted relative to ambient temperature 1~63689 conditions to ensure proper absorption of conductor expansion or contraction. The expansion joints are adjusted by varying the displacement "D" shown in FIGURES 1 and 4 respectively. Note that displacement "D" for a single roller expansion joint is the distance between opposed backing plates 30 whereas the displacement "D" for a double roller expansion joint is one-half this distance. For Alcan B505~ aluminium alloy conductor pipe, "D" is computed according to the formula:
D = 1/2 + L(12)~.000023)~0C - TC) where:
D = expansion joint adjustment displacement, mea-sured in inches L = the length of the conductor segment which the expansion joint is to enable to expand or con-tract. If the conductor segment is rigidly fixed at one end, then one expansion joint must absorb expansion or contraction along the entire length "L~ of the segment. Otherwise, if expansion joints are provided at both ends of the conductor segment, then each expansion joint need absorb only expansions or contrac-tions expected along 1/2 of the length "L" of the conductor segment.
T = the ambient bus bar temperature at the time of installation of the expansion joint. ~-For a single roller expansion joint used with Alcan B505~ 3-inch inside diameter aluminium alloy con-ductor pipe, "D" should be no greater than 3n. For a g double roller expansion joint used with the same conduc-tor pipe, "D" should be a maximum of 2".
Conductor Se ~ent Roller S~ t Structure Base plate 24, roller brackets 26 and rollers 28 may be used separately from the expansion joint elements to support a conductor segment at points where allowance or longitudinal movement need not be made.
For example, it may be convenient to mount base plate 24, roller bracket 26 and rollers 28 at the top of an insulator stack to rollably support a conductor segment between the rollers at the top of the insulator stack.
As will be apparent to those skilled in the art in the light of the foregoing disclosure, many alterations and modifications are possible in the practice of this invention without departing from the spirit or scope thereof. Accordingly, the scope of the invention is to be construed in accordance with the substance defined by the following claims.
Claims (13)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A roller expansion joint for enabling longi-tudinal changes of dimension within a current carrying conductor, said roller expansion joint comprising:
(a) an electrically conductive expansion loop for affixation to an end of said conductor; and, (b) roller means for rollably supporting said conductor.
(a) an electrically conductive expansion loop for affixation to an end of said conductor; and, (b) roller means for rollably supporting said conductor.
2. A roller expansion joint as defined in claim 1, wherein said expansion loop comprises a plurality of spaced apart laminations.
3. A roller expansion joint as defined in claim 2, wherein said roller means comprises a pair of rollers for positioning adjacent opposed sides of said conductor for rollably supporting said conductor.
4. A roller expansion joint as defined in claim 1, 2 or 3, wherein said expansion loop includes:
(a) a first end for affixation to said conductor end; and, (b) a second end for rigid terminal connection.
(a) a first end for affixation to said conductor end; and, (b) a second end for rigid terminal connection.
5. A roller expansion joint as defined in claim 1, 2, or 3, wherein said expansion loop includes:
(a) a first end for affixation to an end of a first segment of said conductor; and, - Page 1 of Claims -(b) a second end for affixation to an end of a second segment of said conductor.
(a) a first end for affixation to an end of a first segment of said conductor; and, - Page 1 of Claims -(b) a second end for affixation to an end of a second segment of said conductor.
6. A roller expansion joint as defined in claim 1, 2, or 3, wherein said expansion loop includes:
(a) a first end for affixation to an end of a first segment of said conductor; and, (b) a second end for affixation to an end of a second segment of said conductor;
and wherein said roller means comprises:
(c) a first pair of rollers for positioning adjacent opposed sides of said first conductor segment for rollably supporting said first conductor segment; and, (d) a second pair of rollers for positioning adjacent opposed sides of said second conductor segment for rollably supporting said second conductor segment.
(a) a first end for affixation to an end of a first segment of said conductor; and, (b) a second end for affixation to an end of a second segment of said conductor;
and wherein said roller means comprises:
(c) a first pair of rollers for positioning adjacent opposed sides of said first conductor segment for rollably supporting said first conductor segment; and, (d) a second pair of rollers for positioning adjacent opposed sides of said second conductor segment for rollably supporting said second conductor segment.
7. A roller expansion joint as defined in claim 1, 2 or 3, wherein said expansion loop includes:
(a) a first end for affixation to said conductor end; and, (b) a second end for rigid terminal connection;
and wherein said expansion loop first end is welded to said conductor end.
(a) a first end for affixation to said conductor end; and, (b) a second end for rigid terminal connection;
and wherein said expansion loop first end is welded to said conductor end.
8. A roller expansion joint as defined in claim 1, 2, or 3, wherein said expansion loop includes:
- Page 2 of Claims -(a) a first end for affixation to an end of a first segment of said conductor; and, (b) a second end for affixation to an end of a second segment of said conductor;
and wherein said expansion loop first end is welded to said first conductor segment end and wherein said expansion loop second end is welded to said second conductor segment end.
- Page 2 of Claims -(a) a first end for affixation to an end of a first segment of said conductor; and, (b) a second end for affixation to an end of a second segment of said conductor;
and wherein said expansion loop first end is welded to said first conductor segment end and wherein said expansion loop second end is welded to said second conductor segment end.
9. A roller expansion joint as defined in claim 1, 2, or 3, wherein said expansion loop is formed of the same material as said conductor.
10. A roller expansion joint as defined in claim 1, 2 or 3, wherein said expansion loop includes:
(a) a first end for affixation to said conductor end; and, (b) a second end for rigid terminal connection;
and further comprising a conductor extension member for affixation between said conductor end and said expansion loop first end.
(a) a first end for affixation to said conductor end; and, (b) a second end for rigid terminal connection;
and further comprising a conductor extension member for affixation between said conductor end and said expansion loop first end.
11. A roller expansion joint as defined in claim 1, 2, or 3, wherein said expansion loop includes:
(a) a first end for affixation to an end of a first segment of said conductor; and, (b) a second end for affixation to an end of a second segment of said conductor;
and wherein said roller means comprises:
- Page 3 of Claims -(c) a first pair of rollers for positioning adjacent opposed sides of said first conductor segment for rollably supporting said first conductor segment; and, (d) a second pair of rollers for positioning adjacent opposed sides of said second conductor segment for rollably supporting said second conductor segment;
and further comprising:
(e) a first conductor extension member for affixation between said expansion loop first end and said first conductor segment end; and, (f) a second conductor extension member for affixation between said expansion loop second end and said second conductor segment end.
(a) a first end for affixation to an end of a first segment of said conductor; and, (b) a second end for affixation to an end of a second segment of said conductor;
and wherein said roller means comprises:
- Page 3 of Claims -(c) a first pair of rollers for positioning adjacent opposed sides of said first conductor segment for rollably supporting said first conductor segment; and, (d) a second pair of rollers for positioning adjacent opposed sides of said second conductor segment for rollably supporting said second conductor segment;
and further comprising:
(e) a first conductor extension member for affixation between said expansion loop first end and said first conductor segment end; and, (f) a second conductor extension member for affixation between said expansion loop second end and said second conductor segment end.
12. A roller expansion joint as defined in claim 1, 2 or 3, wherein said expansion loop includes:
(a) a first end for affixation to said conductor end; and, (b) a second end for rigid terminal connection;
and further comprising guide means for preventing rotation of said conductor about a longitudinal axis thereof.
(a) a first end for affixation to said conductor end; and, (b) a second end for rigid terminal connection;
and further comprising guide means for preventing rotation of said conductor about a longitudinal axis thereof.
13. A roller expansion joint as defined in claim 2, wherein adjacent laminations of said expansion loop are spaced apart by at least 1.6 mm.
- Page 4 of Claims -
- Page 4 of Claims -
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US31462681A | 1981-10-26 | 1981-10-26 | |
| US314,626 | 1981-10-26 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1163689A true CA1163689A (en) | 1984-03-13 |
Family
ID=23220729
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000401761A Expired CA1163689A (en) | 1981-10-26 | 1982-04-27 | Roller expansion joint |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1163689A (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4582373A (en) * | 1984-10-23 | 1986-04-15 | Square D Company | Expansion terminal connector |
| CN113612091A (en) * | 2021-08-02 | 2021-11-05 | 北京航空航天大学 | Large-current sliding conductive device suitable for self-resistance heating hot stretch bending equipment |
-
1982
- 1982-04-27 CA CA000401761A patent/CA1163689A/en not_active Expired
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4582373A (en) * | 1984-10-23 | 1986-04-15 | Square D Company | Expansion terminal connector |
| CN113612091A (en) * | 2021-08-02 | 2021-11-05 | 北京航空航天大学 | Large-current sliding conductive device suitable for self-resistance heating hot stretch bending equipment |
| CN113612091B (en) * | 2021-08-02 | 2022-04-01 | 北京航空航天大学 | Large-current sliding conductive device suitable for self-resistance heating hot stretch bending equipment |
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| Date | Code | Title | Description |
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| MKEX | Expiry |