CA1069191A - Heat recoverable article for electrically insulating bus bar - Google Patents
Heat recoverable article for electrically insulating bus barInfo
- Publication number
- CA1069191A CA1069191A CA232,849A CA232849A CA1069191A CA 1069191 A CA1069191 A CA 1069191A CA 232849 A CA232849 A CA 232849A CA 1069191 A CA1069191 A CA 1069191A
- Authority
- CA
- Canada
- Prior art keywords
- article
- heat
- sleeve
- liner
- electrically insulating
- 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.)
- Expired
Links
Classifications
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02G—INSTALLATION OF ELECTRIC CABLES OR LINES, OR OF COMBINED OPTICAL AND ELECTRIC CABLES OR LINES
- H02G5/00—Installations of bus-bars
- H02G5/02—Open installations
Landscapes
- Cable Accessories (AREA)
- Insulating Bodies (AREA)
- Sealing Material Composition (AREA)
Abstract
A B S T R A C T
Disclosed is a heat-recoverable article particularly useful for electrically insulating and covering bus bars. The article, which is hollow and has at least one open end, comprises a heat-shrinkable sleeve and an electrically conducting liner covering at least a portion of its inner surface. Upon recovery on a substrate the liner remains in contact with the sleeve. The end portion of the sleeve is provided with electrically insulating sealant. The liner is advantageously a mastic, a hot melt ad-hesive or a thermosetting adhesive.
Disclosed is a heat-recoverable article particularly useful for electrically insulating and covering bus bars. The article, which is hollow and has at least one open end, comprises a heat-shrinkable sleeve and an electrically conducting liner covering at least a portion of its inner surface. Upon recovery on a substrate the liner remains in contact with the sleeve. The end portion of the sleeve is provided with electrically insulating sealant. The liner is advantageously a mastic, a hot melt ad-hesive or a thermosetting adhesive.
Description
" ` ~069~9~
This invention relates to an art7cle, especially a heat-recoverable ar~Tcle and m~re especially a heat-recoverable article for the purpose of ` electrically insulating and covering bus bars for electrical equipment, By a heat-recoverable article there Ts meant one which has been deformed, for example, under heat and/or pre-sure from an original configuration to a dimensionally heat unstable configuration and which has been caused to remain in said heat unstable conf~iguration, for example by cooling whilst maintatning the pressure, the a~ticle being capable of returning to its original config-uration upon the application of heat alone.
In the past, bus bars have been electrically Insulated by submersion in an oil-filled container or by a cover;ng of polyvTnyl chloride material or epoxy resin or resin bonded paper. Such electrically insulating cover7ngs have at best a one minute electric strength of between 10 and 15 kilovolts per mm thtckness, ., Bus bars submersed In oll operate effectively at up to 11 kV if the 1 next nearest parallel bus bar ls at an edge-to-edge distance of at least 25 mn-.
'~ Oil immersion tanks are however, bulky and heavy and do not faci;itate access to the bus bars.
The other mentloned electrically insulating systems require a sur~ace-20~ to-surface separation between bus bars of at least 50 mm if the bus bars are carrylng 11 kV operatTng voltage. Closer plac1ng of the operatlng bus bars results In corona discharge, Under short clrcutt conditlons, the temperature of a bus bar may rise ~ as high as 250C for very short periods of time and the insulation must exhlbit 1 25 effectlve Insulatlng propertles thereafter. Transformer oll can withstand such temperature rlses very successfully, but epoxy resins crack as a result of thermal expanston, while non-crossllnked polyvinyl chloride coverings, above a temperature of 100C, melt and drip off the bus bars.
:, By the present Inventton, parallel placing of bus bars operating at, for - example, li kV with a separation of 40 mm depending on bus bar geometry, ` ~
.
:: , . . ~
:: .
. ~ .
" . .
10~ 91 .s possi~le, and in certain circumstances an electrical strength of at least 30 ~kV/~m, ~en the voltage is Ipplied through the bus bar insulation for one minute, is achieved.
The present invention provides a heat-recoverable hollow article, having at least one open end, which comprises a heat-shrinkable sleeve, at least one portion of the inner surface of which is provided with an electrically conducttng liner, such that when the heat-recoverable article is recovered on to a substrate, the electrlcallyconducting llner remains in contact with the sleeve throughout the length of said sleeve portion, so that there are no volds between the sleeve and the liner and the, or at least one, end portion of tl-e inner surface of which sleeve is provided with an electrically insulating sealant.
The present tnventlon also provldes a process for electrically insulating a jotnt between bus bars wherein the hèat-recoverable hollow article of the tnvention Is caused to shrink over the joint so that the joint lies withTn a faraday cage and the sealant provides a barrier against moisture ingress.
The present invention further provides a tee-shaped metallic bus bar surrounded by an electrically insulating crosslinked polymeric material.
The present invention still further provides a kit of parts, comprlsing ; 20 the heat-recoverable hollow article of the Tnvention, a tee-shaped metalllc bus bar surrounded by an electrically Tnsulattng, c~ossllnked polymeric materlal and heat-recoverable polymerlc tubing having a one mlnute electrlc strength of at least 30 kV/mm.
The term "bus bar" Is hereln used to describe what is meant by the terms "bus bar", "bus rod" and "bus shape", the definitlon of each of which may be found Tn ASTM B187-74.
In general, a heat-recoverable artlcle such as that provided by the present Tnvention ts of a material capable of having the property of plastic or elastic memory imparted thereto and has been expanded under pressure and/or heat to a size greater than its ortginal size and cooled while ma7ntainin3 - ' , ' ' '~ ' ,- , -~ts expanded configura~ion. An article treated in this manner retains an expanded con~iguration until it i-q again heated to at least its heat recovery temperature or temperature range when `; it recovers to or towards its original shape.
Examples of preferred materials useful in forming a dimensionally heatshrinkable sleeve or the heat-recoverable tubing according to the present invention may be found in British Patent Nos. 1,337,951 and 1,337,952 both published on 21st l November, 1973 and 1,303,432 published 17th January, 1973 all in ! lo the name of Raychem Limited. The materials disclosed therein are track-resistant, an advantageous property of bus bar insula-tion for protection against tracking failure caused by water condensation on the ourface thereof.
.
The electrically conducting liner of the-~present invention - 15 may be of any polymeric material to which the property of electrical conductivity has been imparted by incorporation of quantities of conductive filler, for example, carbon black or metal flakes or powders, for example, silver flake or copper powder. It i8 e~sential that during use the liner i8 in void-free contact through-out its length with the sleeve. To this end it i8 advantageousfor the liner to be a maJtic, a hot melt adhesive or a thermo-setting adhesive. As mastic composition's there may be especially mentioned poly iso butylene or rubbers?,~ for example, butyl rubber or epichlorohydrin based rubbers to which suitable plasticisers ¦ 25 and tackifiers have been added as required. As suitable hot melt adhesive compositions there may be especially mentioned copolymers of ethylene, e.g. ethylene~vinyl acetate, ethylene/acrylic acid.
Any of these compositions may include conventional additives, e.g.
processing aids and antioxidants, as required.
;l 30 Alternatively, the liner may be of a plastic material not : normally regarded as having adheqive characteristics in which a . , .
. . .
. ' " . ' ... - . ~ : .: .
-: ~
`-` 1069~91 conductive filler has been incorporated. Examples of such materials include poly~lefin~ for example, vinyl chloride, polyvinylidene fluoride and homo-, co- or ter- polymers of hexafluoroethylene. The liner may advantageously be formed from these materials.
A particularly advantageous met~od of manufacture of the heat-recoverable article according to the invention is dual extrusion whereby the sleeve and the liner are extruded simultaneously and drawn together (for example, as disclosed in British Patent No~
1,033,959 published 22 June, 1966 in the name of Raychem Corporation. The resulting article may be subjected to irradiation to cross-link it. The depth of penetration of the irradiation may be varied as required so that the material at the dividing line between the sleeve and the electrically conducting liner may be cross-linked to join these two intimately.
A sleeve and a liner may be extruded separately, the liner ~ placed inside the sleeve and bonded securely thereto. The material ; of the liner and/or of the sleeve may be cross-linked before or after this step and the liner may have the property of plastic or elastic memory imparted thereto as desired.
The, or each, open end portion of the heat-shrinkable sleeve, according to the present invention, is provided with an electrically insulating adhesive, mastic or thermosetting adhesive which is capable of oealing to provide a barrier against moisture ingress under the sleeve through the, or each, end portion thereof.
The tee-shaped, one-piece metallic bus bar, according to the present invention, provides a very useful replacement for the conventional, perpendicularly ~ointed bus bar ~ystem, since the ~mooth surface which may result from this substantially reduces corona discharge. Electrical insulation of a tee-shaped metallic bus bar, according to the present invention, i8 provided by a cross-linked polymeric material, moulded in place about the rnetallic bus bar. The material is advantageously one of those disclosed in British Patent Nos. 1,337 951 1,337 952 and 1 303,432.
The cross-linked polymeric material of the present invention advantageously has a one minute electric strength of at least 30 kV/mm.
Whilst the article of the present invention is especially useful for the purpose of electrically insulating a bus bar, it may be used equally well for electrical insulation of any other electrical conductor.
- , - , , : ~
'- - ' ' . ' , ,. ~, , . . , . - : .
,, - ' 106919~
Several forms of articlés of the present invention will now be described by way of example only, with reference to the accompanying drawings in which:
Figure 1 is an axial sectional view of an article constructed in accordance with the present invention;
Figure 2 is an isometric view partly in section of the view of Figure 1 positioned over jointed bus bars;
Figure 3 is an isometric view in section of an article of Figure 1 after recovery onto jointed bus bars;
Figure 4 is an isometric view of a cross-linked polymeric article ; moulded in place on a tee-shaped metallic article;
Figure 5 is a graph showing the dependence of the discharge inception voltage on the distance from the joint to earth, for various joints insulated by the article of the present invention.
Referring now to the drawings, Figures 1 and 2 show a heat-recoverable article, cons~ructed in accordance with the present invention, indicated generally by reference numeral 1. A heat-shrinkable sleeve 2, is provided with an electrically conducting liner 3, and an electrically insulating sealant 4. As shown diagrammatically in Figure 3, on heating the article, the sleeve 2, shrinks, and the liner 3, is forced toward the bus bars and may be, if desired, caused to melt or soften sufficiently to cause all gaps and irregularities to be filled (not shown for clarity).
Referring now to Figure 4, there is shown a T-shaped bus bar 6, the region of which close to and at the junction of the upright and the crossbar of the tee is encapsulated by a layer 5 of a crosslinked polymeric material.
The following examples illustrate the invention:
Example 1 Bolted bus bar joints were electrically insulated and the dis-B ~ 6 _ _ 106919~
charge inception voltage was plotted against the joint-to earth distance.
Bus Bar ~oint No. 1 2 3 4 . Insulation None Polyisobutylene- Heat-shrinkable Heat-shrinkable Type containing putty polyethylene- polyethylene-containing containing tubing tubing Conductive None None None Polyisobutylene Liner containing - :
conductive mastic Sealant None None Butyl rubber Butyl rubber adhesive tape adhesive tape :
. .
,. . .
.
:
: .
R
-6a-. . .
: . - .
The ~raph (Figure 5) illustrates the substantial improvement in discharge _.
inception voltage obtained especially at low joint-to earth distances on tnsulating bolted bus bar joints according to the present invention, the numbered curves corresponding to ~he joint numbers above.
Examp!e 2.
Power Frequency Test.
A sample of tubing constructed in accordance with the third aspect o~ the invention (Raychem BBIT) was heat recovered on a length of bus bar and a conductive paint was applied over 7 cm length of the outer surface of the tubing.
A semi-conductive tubing was heat-recovered over the edyes only of this paint leavlng 5 cm o~ the paint uncovered. The voltage applied through the bus bar was Increased in 5 kV at one minute intervals from 15 kV. The paint layer was earthed. As a comparlson, the Raychem BBIT tubing was replaced by a commercially avajlable heat-shrinkable PVC tubing:
Results:
Tublnq Tublnq Thickness(mmj Breakdown Breakdown ! Voltaqe ~kV rms) Stress (rms kV/mm) !
Raychem BBIT 1.86 70 37.5 Heat-ShrTnk~ble PVC 2.~ 35 _ 15_ _ _ ~_ .
Example 3 Impulse Withstand Voltage Comparison.
`, The insulated bus bars were prepared as in Example 2. The Impulse voltage was 1 ~ound incteaslng the voltage In approxlmately 5 kV steps, 10 pulses being .; .
applled at each test level. A posltive polarity 1/50~ sec. pulse was used in accordance with the test B.S. 923,1972.
Tubing Tublnq Thickness(mm) Withstand Voltage Withstand Stress kV ~! mpulse) (peak kVfmm) ~; Raychem BBIT 1.9 105 55 Heat-shrinkable PVC 1.98 60 30 \, .
' 1069~9~
. ~ ~ The results from Examples 2 and 3 sllow that surface-to-surface ~.~
separation of bus bars may be reduced using material which has lmproved breakdown and voltage wi~hstand properties.
.
- :
.
., .
This invention relates to an art7cle, especially a heat-recoverable ar~Tcle and m~re especially a heat-recoverable article for the purpose of ` electrically insulating and covering bus bars for electrical equipment, By a heat-recoverable article there Ts meant one which has been deformed, for example, under heat and/or pre-sure from an original configuration to a dimensionally heat unstable configuration and which has been caused to remain in said heat unstable conf~iguration, for example by cooling whilst maintatning the pressure, the a~ticle being capable of returning to its original config-uration upon the application of heat alone.
In the past, bus bars have been electrically Insulated by submersion in an oil-filled container or by a cover;ng of polyvTnyl chloride material or epoxy resin or resin bonded paper. Such electrically insulating cover7ngs have at best a one minute electric strength of between 10 and 15 kilovolts per mm thtckness, ., Bus bars submersed In oll operate effectively at up to 11 kV if the 1 next nearest parallel bus bar ls at an edge-to-edge distance of at least 25 mn-.
'~ Oil immersion tanks are however, bulky and heavy and do not faci;itate access to the bus bars.
The other mentloned electrically insulating systems require a sur~ace-20~ to-surface separation between bus bars of at least 50 mm if the bus bars are carrylng 11 kV operatTng voltage. Closer plac1ng of the operatlng bus bars results In corona discharge, Under short clrcutt conditlons, the temperature of a bus bar may rise ~ as high as 250C for very short periods of time and the insulation must exhlbit 1 25 effectlve Insulatlng propertles thereafter. Transformer oll can withstand such temperature rlses very successfully, but epoxy resins crack as a result of thermal expanston, while non-crossllnked polyvinyl chloride coverings, above a temperature of 100C, melt and drip off the bus bars.
:, By the present Inventton, parallel placing of bus bars operating at, for - example, li kV with a separation of 40 mm depending on bus bar geometry, ` ~
.
:: , . . ~
:: .
. ~ .
" . .
10~ 91 .s possi~le, and in certain circumstances an electrical strength of at least 30 ~kV/~m, ~en the voltage is Ipplied through the bus bar insulation for one minute, is achieved.
The present invention provides a heat-recoverable hollow article, having at least one open end, which comprises a heat-shrinkable sleeve, at least one portion of the inner surface of which is provided with an electrically conducttng liner, such that when the heat-recoverable article is recovered on to a substrate, the electrlcallyconducting llner remains in contact with the sleeve throughout the length of said sleeve portion, so that there are no volds between the sleeve and the liner and the, or at least one, end portion of tl-e inner surface of which sleeve is provided with an electrically insulating sealant.
The present tnventlon also provldes a process for electrically insulating a jotnt between bus bars wherein the hèat-recoverable hollow article of the tnvention Is caused to shrink over the joint so that the joint lies withTn a faraday cage and the sealant provides a barrier against moisture ingress.
The present invention further provides a tee-shaped metallic bus bar surrounded by an electrically insulating crosslinked polymeric material.
The present invention still further provides a kit of parts, comprlsing ; 20 the heat-recoverable hollow article of the Tnvention, a tee-shaped metalllc bus bar surrounded by an electrically Tnsulattng, c~ossllnked polymeric materlal and heat-recoverable polymerlc tubing having a one mlnute electrlc strength of at least 30 kV/mm.
The term "bus bar" Is hereln used to describe what is meant by the terms "bus bar", "bus rod" and "bus shape", the definitlon of each of which may be found Tn ASTM B187-74.
In general, a heat-recoverable artlcle such as that provided by the present Tnvention ts of a material capable of having the property of plastic or elastic memory imparted thereto and has been expanded under pressure and/or heat to a size greater than its ortginal size and cooled while ma7ntainin3 - ' , ' ' '~ ' ,- , -~ts expanded configura~ion. An article treated in this manner retains an expanded con~iguration until it i-q again heated to at least its heat recovery temperature or temperature range when `; it recovers to or towards its original shape.
Examples of preferred materials useful in forming a dimensionally heatshrinkable sleeve or the heat-recoverable tubing according to the present invention may be found in British Patent Nos. 1,337,951 and 1,337,952 both published on 21st l November, 1973 and 1,303,432 published 17th January, 1973 all in ! lo the name of Raychem Limited. The materials disclosed therein are track-resistant, an advantageous property of bus bar insula-tion for protection against tracking failure caused by water condensation on the ourface thereof.
.
The electrically conducting liner of the-~present invention - 15 may be of any polymeric material to which the property of electrical conductivity has been imparted by incorporation of quantities of conductive filler, for example, carbon black or metal flakes or powders, for example, silver flake or copper powder. It i8 e~sential that during use the liner i8 in void-free contact through-out its length with the sleeve. To this end it i8 advantageousfor the liner to be a maJtic, a hot melt adhesive or a thermo-setting adhesive. As mastic composition's there may be especially mentioned poly iso butylene or rubbers?,~ for example, butyl rubber or epichlorohydrin based rubbers to which suitable plasticisers ¦ 25 and tackifiers have been added as required. As suitable hot melt adhesive compositions there may be especially mentioned copolymers of ethylene, e.g. ethylene~vinyl acetate, ethylene/acrylic acid.
Any of these compositions may include conventional additives, e.g.
processing aids and antioxidants, as required.
;l 30 Alternatively, the liner may be of a plastic material not : normally regarded as having adheqive characteristics in which a . , .
. . .
. ' " . ' ... - . ~ : .: .
-: ~
`-` 1069~91 conductive filler has been incorporated. Examples of such materials include poly~lefin~ for example, vinyl chloride, polyvinylidene fluoride and homo-, co- or ter- polymers of hexafluoroethylene. The liner may advantageously be formed from these materials.
A particularly advantageous met~od of manufacture of the heat-recoverable article according to the invention is dual extrusion whereby the sleeve and the liner are extruded simultaneously and drawn together (for example, as disclosed in British Patent No~
1,033,959 published 22 June, 1966 in the name of Raychem Corporation. The resulting article may be subjected to irradiation to cross-link it. The depth of penetration of the irradiation may be varied as required so that the material at the dividing line between the sleeve and the electrically conducting liner may be cross-linked to join these two intimately.
A sleeve and a liner may be extruded separately, the liner ~ placed inside the sleeve and bonded securely thereto. The material ; of the liner and/or of the sleeve may be cross-linked before or after this step and the liner may have the property of plastic or elastic memory imparted thereto as desired.
The, or each, open end portion of the heat-shrinkable sleeve, according to the present invention, is provided with an electrically insulating adhesive, mastic or thermosetting adhesive which is capable of oealing to provide a barrier against moisture ingress under the sleeve through the, or each, end portion thereof.
The tee-shaped, one-piece metallic bus bar, according to the present invention, provides a very useful replacement for the conventional, perpendicularly ~ointed bus bar ~ystem, since the ~mooth surface which may result from this substantially reduces corona discharge. Electrical insulation of a tee-shaped metallic bus bar, according to the present invention, i8 provided by a cross-linked polymeric material, moulded in place about the rnetallic bus bar. The material is advantageously one of those disclosed in British Patent Nos. 1,337 951 1,337 952 and 1 303,432.
The cross-linked polymeric material of the present invention advantageously has a one minute electric strength of at least 30 kV/mm.
Whilst the article of the present invention is especially useful for the purpose of electrically insulating a bus bar, it may be used equally well for electrical insulation of any other electrical conductor.
- , - , , : ~
'- - ' ' . ' , ,. ~, , . . , . - : .
,, - ' 106919~
Several forms of articlés of the present invention will now be described by way of example only, with reference to the accompanying drawings in which:
Figure 1 is an axial sectional view of an article constructed in accordance with the present invention;
Figure 2 is an isometric view partly in section of the view of Figure 1 positioned over jointed bus bars;
Figure 3 is an isometric view in section of an article of Figure 1 after recovery onto jointed bus bars;
Figure 4 is an isometric view of a cross-linked polymeric article ; moulded in place on a tee-shaped metallic article;
Figure 5 is a graph showing the dependence of the discharge inception voltage on the distance from the joint to earth, for various joints insulated by the article of the present invention.
Referring now to the drawings, Figures 1 and 2 show a heat-recoverable article, cons~ructed in accordance with the present invention, indicated generally by reference numeral 1. A heat-shrinkable sleeve 2, is provided with an electrically conducting liner 3, and an electrically insulating sealant 4. As shown diagrammatically in Figure 3, on heating the article, the sleeve 2, shrinks, and the liner 3, is forced toward the bus bars and may be, if desired, caused to melt or soften sufficiently to cause all gaps and irregularities to be filled (not shown for clarity).
Referring now to Figure 4, there is shown a T-shaped bus bar 6, the region of which close to and at the junction of the upright and the crossbar of the tee is encapsulated by a layer 5 of a crosslinked polymeric material.
The following examples illustrate the invention:
Example 1 Bolted bus bar joints were electrically insulated and the dis-B ~ 6 _ _ 106919~
charge inception voltage was plotted against the joint-to earth distance.
Bus Bar ~oint No. 1 2 3 4 . Insulation None Polyisobutylene- Heat-shrinkable Heat-shrinkable Type containing putty polyethylene- polyethylene-containing containing tubing tubing Conductive None None None Polyisobutylene Liner containing - :
conductive mastic Sealant None None Butyl rubber Butyl rubber adhesive tape adhesive tape :
. .
,. . .
.
:
: .
R
-6a-. . .
: . - .
The ~raph (Figure 5) illustrates the substantial improvement in discharge _.
inception voltage obtained especially at low joint-to earth distances on tnsulating bolted bus bar joints according to the present invention, the numbered curves corresponding to ~he joint numbers above.
Examp!e 2.
Power Frequency Test.
A sample of tubing constructed in accordance with the third aspect o~ the invention (Raychem BBIT) was heat recovered on a length of bus bar and a conductive paint was applied over 7 cm length of the outer surface of the tubing.
A semi-conductive tubing was heat-recovered over the edyes only of this paint leavlng 5 cm o~ the paint uncovered. The voltage applied through the bus bar was Increased in 5 kV at one minute intervals from 15 kV. The paint layer was earthed. As a comparlson, the Raychem BBIT tubing was replaced by a commercially avajlable heat-shrinkable PVC tubing:
Results:
Tublnq Tublnq Thickness(mmj Breakdown Breakdown ! Voltaqe ~kV rms) Stress (rms kV/mm) !
Raychem BBIT 1.86 70 37.5 Heat-ShrTnk~ble PVC 2.~ 35 _ 15_ _ _ ~_ .
Example 3 Impulse Withstand Voltage Comparison.
`, The insulated bus bars were prepared as in Example 2. The Impulse voltage was 1 ~ound incteaslng the voltage In approxlmately 5 kV steps, 10 pulses being .; .
applled at each test level. A posltive polarity 1/50~ sec. pulse was used in accordance with the test B.S. 923,1972.
Tubing Tublnq Thickness(mm) Withstand Voltage Withstand Stress kV ~! mpulse) (peak kVfmm) ~; Raychem BBIT 1.9 105 55 Heat-shrinkable PVC 1.98 60 30 \, .
' 1069~9~
. ~ ~ The results from Examples 2 and 3 sllow that surface-to-surface ~.~
separation of bus bars may be reduced using material which has lmproved breakdown and voltage wi~hstand properties.
.
- :
.
., .
Claims (13)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A heat-recoverable hollow article having at least one open end, comprising a heat-shrinkable sleeve at least one portion of the inner surface of which is provided with an electrically conducting liner, which liner, upon recovery of the article onto a substrate, remains in void-free contact with the sleeve throughout the length of said sleeve portion and the, or at least one, open end portion of the inner surface of the article is provided with an electrically insulating sealant.
2. An article as claimed in claim 1 wherein the material of the sleeve is cross-linked.
3. An article as claimed in claim 1 wherein at least the outer surface of the sleeve is track-resistant.
4. An article as claimed in any one of claims 1, 2 or 3 wherein the electrically conducting liner extends along the total length of the inner surface of the heat-shrinkable sleeve and the electrically insulating sealant is positioned on the or each end portion of the inner surface of the liner.
5. An article as claimed in any one of claims 1, 2 or 3 wherein the central portion of the inner surface of the heat-shrinkable sleeve is provided with the electrically conducting liner and the or each end portion of the inner surface of the sleeve is provided with the electrically insulating sealant.
6. An article as claimed in claim 1 wherein the electrically conducting liner is of a polymeric material rendered electrically conducting by the presence of an electrically conducting filler.
7. An article as claimed in claim 6 wherein the polymeric material of the electrically conducting liner is a mastic, a hot melt adhesive or a thermosetting adhesive.
8. An article as claimed in claim 6 wherein the polymeric material of the electrically conducting liner is cross-linked.
9. An article as claimed in claim 8 wherein the electrically conducting liner is heat-shrinkable.
10. An article as claimed in claim 1 wherein the electrically insulating sealant is a mastic, a hot-melt adhesive or a thermosetting adhesive.
11. A process for electrically insulating a bus bar joint wherein a heat-recoverable hollow article having at least one open end, comprising a heat-shrinkable sleeve at least one portion of the inner surface of which is provided with an electrically conducting liner, which liner, upon recovery of the article onto a substrate, remains in void-free contact with the sleeve throughout the length of said sleeve portion and the, or at least one, open end portion of the inner surface of the article is provided with an electrically insulating sealant is heat-recovered over the joint and the sealant seals against moisture ingress.
12. A kit of parts comprising a heat-recoverable article according to claim 1, a tee-shaped solid metallic bus bar surrounded by an electrically insulating cross-linked polymeric material, and a heat-recoverable polymeric tubing having a one minute electric strength of at least 30 kV/mm.
13. A kit as claimed in claim 12, wherein the electrically insulating cross-linked polymeric material is track resistant.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB3439574A GB1514924A (en) | 1974-08-05 | 1974-08-05 | Heat recoverable article |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1069191A true CA1069191A (en) | 1980-01-01 |
Family
ID=10365124
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA232,849A Expired CA1069191A (en) | 1974-08-05 | 1975-08-05 | Heat recoverable article for electrically insulating bus bar |
Country Status (4)
| Country | Link |
|---|---|
| CA (1) | CA1069191A (en) |
| DE (1) | DE2534385A1 (en) |
| FR (1) | FR2281663A1 (en) |
| GB (1) | GB1514924A (en) |
Families Citing this family (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4151364A (en) * | 1976-09-29 | 1979-04-24 | Ellis J Scott | Electrical connectors and methods of connecting electrical conductors |
| AU531523B2 (en) * | 1978-12-01 | 1983-08-25 | Raychem Gmbh | Electrical apparatus |
| US4304616A (en) * | 1979-04-02 | 1981-12-08 | Raychem Corporation | Radially shrinkable sleeves |
| US4658504A (en) * | 1985-08-23 | 1987-04-21 | Westinghouse Electric Corp. | Method for insulating conductor joints particularly bus bars and insulated bus bar apparatus |
| GB8629764D0 (en) * | 1986-12-12 | 1987-01-21 | Bowthorpe Hellermann Ltd | Electrical connector |
| US4802509A (en) * | 1987-12-15 | 1989-02-07 | Brandolf Henry E | Wraparound closure for conduit protection |
| GB8916027D0 (en) * | 1989-07-13 | 1989-08-31 | Vactite Ltd | Electrical conductor |
| AR244474A1 (en) * | 1990-08-24 | 1993-10-29 | Siemens Ag | Device for connection of bars |
| DE4444151A1 (en) * | 1994-12-12 | 1996-06-13 | Hagen Batterie Ag | Storage battery cells arrangement |
| DE10023204A1 (en) * | 2000-05-12 | 2001-11-15 | Alstom Power Nv | Insulation of stator windings with shrink sleeves |
Family Cites Families (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3297819A (en) * | 1964-08-10 | 1967-01-10 | Raychem Corp | Heat unstable covering |
| GB1265194A (en) * | 1968-08-15 | 1972-03-01 | ||
| FR1585488A (en) * | 1968-09-19 | 1970-01-23 | ||
| US3755616A (en) * | 1971-09-15 | 1973-08-28 | Westinghouse Electric Corp | Thermoplastic sealed-sheath covering upon electrical bus-bar conductors |
-
1974
- 1974-08-05 GB GB3439574A patent/GB1514924A/en not_active Expired
-
1975
- 1975-08-01 DE DE19752534385 patent/DE2534385A1/en not_active Ceased
- 1975-08-05 FR FR7524351A patent/FR2281663A1/en active Granted
- 1975-08-05 CA CA232,849A patent/CA1069191A/en not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| FR2281663B1 (en) | 1979-01-05 |
| FR2281663A1 (en) | 1976-03-05 |
| DE2534385A1 (en) | 1976-03-04 |
| GB1514924A (en) | 1978-06-21 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |