WO2013037013A1

WO2013037013A1 - Communications cable conduit

Info

Publication number: WO2013037013A1
Application number: PCT/AU2012/001114
Authority: WO
Inventors: Gianni Dolcetta; James Nardella; Marcello Russo
Original assignee: It3 Ip Pty Ltd
Priority date: 2011-09-16
Filing date: 2012-09-17
Publication date: 2013-03-21
Also published as: AU2012308110A1; AU2012308110B2

Abstract

Disclosed herein is a communications cable conduit system, a method of installing a communications cable conduit system, a communications cable conduit, a method of manufacturing a communications cable conduit, an apparatus for making a communications cable conduit and a method of installing a communications cable conduit.

Description

COMMUNICATIONS CABLE CONDUIT

Field of the Invention The present invention generally relates to

communications cable conduits, and particularly but not exclusively to communications cable conduit systems, components for such systems, an apparatus for making such systems and methods of installation and manufacture.

Background of the Invention

A communications cable is generally housed in a protective conduit. The conduits may be buried. The owner of the conduit, for example a communications service provider, may wish to allow another party, for suitable consideration, to insert communications cables in the conduit. The conduits may protect the cables from trauma, moisture and corrosive elements. These conduits may be difficult to detect and the conduits may be inadvertently dug up during excavation in the vicinity of the conduit which may break the cable. In many circumstances the breakage of a cable is a serious incident.

Summary of Invention

According to a first aspect of the invention there is provided a communications cable conduit comprising:

a conduit body defining a passageway for disposing therein at least one communications cable; and

an electrical conductor, the conductor is for receiving an electrical signal and emitting detectable electromagnetic radiation for discovery of the conduit. In an embodiment, the conductor is incorporated with the body. The conductor may be embedded in the body. The conductor may be embedded in a conduit wall.

The conduit may be buried, for example in earth. At least one communications cable may be disposed within the passageway. When the conduit requires discovery, for example prior to excavation in the vicinity of the conduit, an electrical radio signal generator may be electrically connected to the conductor ("Trace wire") . The activated generator generates a radio frequency electrical signal received by the conductor. The conductor may then in response emit radio waves. These can be detected using, for example, a handheld radio signal detection unit swept over the conduit by a worker.

The conductor ("trace wire") is buried when the conduit is buried. Generally, there is no need to bury the conductor separately, or attached the conductor to the conduit at the burial site. The conductor may be

protected by the body during burial. The conductor may be protected, from trauma and corrosive elements for example, by the body once buried.

In an embodiment, the conductor extends along at least some of the conduit. The conductor may be

longitudinally orientated. The conductor may be straight. Alternatively, the conductor may spiral around the passageway. Generally the conductor may have any suitable configuration.

In an embodiment, the conduit body comprises a polymer. The polymer may comprise high density

polyethylene (HDPE) . Alternatively, the polymer may be any one of polypropylene, acetal, acrylic, nylon (polyamides ) , polystyrene, polyvinyl chloride, acrylonitrile butadiene styrene (ABS) and polycarbonate, for example.

In an embodiment, at least some of the conductor is configured as a wire. At least some of the conductor may be configured as a ribbon. At least some of the conductor may be configured as a mesh. The conductor may take any suitable form.

In an embodiment, the conductor may comprise metal. The metal may comprise stainless steel. The metal may comprise copper and aluminum, for example, or any suitable metal alloy. Alternatively, the conductor may comprise a composite material. The composite material may comprise polymer and conductive particles, such as a metal or carbon particles for example. In yet another alternative, the conductor comprises a conductive polymer. The conductor may comprise any suitable conductive material.

The at least one communications cable may comprise an optical fibre. The at least one communications cables may comprise an electrical cable. The electrical cable may be an electrical data cable, or alternatively may be an electrical power cable.

According to a second aspect of the invention there is provided a method of making a communications cable conduit in accordance with the first aspect of the invention, the method comprising the step of:

extruding a material through a die configured to shape the material in the form of a body of the

communications cable conduit. In an embodiment, the method comprises the step of incorporating the conductor with the body of the

communications cable conduit.

In an embodiment, the die is configured for forming a conduit wall. The conductor may be incorporated with the conduit wall during the extrusion process.

According to a third aspect of the invention, there is provided an apparatus for making a communications cable conduit in accordance with the first aspect of the invention, the apparatus comprising:

an extrusion die configured to shape material passed therethrough to form a conduit body; and

a supplier of conductor arranged to co-operate with the die such that the conductor can be drawn through the die during the extrusion process and incorporated with the body .

According to a forth aspect of the invention, there is provided a communications cable conduit system

comprising:

a first communications cable conduit; and

a multi-passage communications cable conduit that is longitudinally disposed in the first communications cable conduit, the multi-passage communications cable conduit having at least two communications cable receiving passageways, each passageway connecting opposite ends of the multi-passage communications cable conduit.

In an embodiment, the communications cable conduit system comprises a communications cable in one of the first and second conduits. More than one of the

communications cable receiving passageways may have a respective cable or respective plurality of cables. The system may have at least one communications cable in a space between the first communications cable and the multi-passage communications cable. Multiple passages may enable better cable

organisation and management. For example, cables in one passage may be manipulated without affecting the cables in the other passage. The passageways may be made available, for example sold, leased or rented, to a third party.

Each passageway may be provided to different parties.

In some but not all embodiments, the each

communications cable comprise optical fibre.

Alternatively, at least one or more of the communications cables may comprise an electrical cable. According to a fifth aspect of the invention, there is provided a method of installing a communications cable conduit system, the method comprising the step of:

disposing a multi-passage communications cable conduit longitudinally in a first communications cable conduit, the multi-passage communications cable conduit having at least two communications cable receiving passageways, each passageway connecting opposite ends of the multi-passage communications cable conduit.

According to a sixth aspect of the invention, there is provided a method of manufacturing a multi-passage communications cable conduit, the method comprising the step of:

passing an extrudable material through an extrusion die configured for extruding a multi-passage

communications cable conduit having at least two passageways, each passageway connecting opposite ends of the multi-passage communications cable conduit.

In an embodiment, the extrudable material is high density polyethylene. Alternatively, the material may be any one of polypropylene, acetal, acrylic, nylon

(polyamides ) , polystyrene, polyvinyl chloride,

acrylonitrile butadiene styrene (ABS) and polycarbonate, for example.

According to a seventh aspect of the invention, there is provided a method of installing communications cables, the method comprising the steps of:

installing a communications cable conduit system in accordance with the second aspect of the invention; and disposing one or more communications cables in at least one of the communications cable receiving

passageways .

According to an eighth aspect of the invention, there is provided a multi-passage communications cable conduit comprising an extruded body having an outer wall and an inner wall disposed longitudinally within the outer wall to form two communications cable receiving passageways, each passageway connecting opposite ends of the conduit.

Brief description of the Figures

In order to achieve a better understanding of the nature of the present invention embodiments of the invention will now be described, by way of example only, with reference to the accompanying figures in which:

Figure 1 shows a perspective view of one embodiment of a communications cable conduit; Figure 2 shows a schematic view of one example of a section of a die for making the communications cable conduit; and

Figure 3 shows a photograph of an end of an example extruder having the die of figure 2, and a wire being pulled through the wire.

Figure 4 which shows a transverse section of a communications cable conduit; and

Figure 5 shows a schematic view of one example of a section of a die for making the communications cable conduit .

Detailed Description of embodiments of the invention Figure 1 shows a perspective view of one embodiment of a communications cable conduit generally indicated by the numeral 10. The conduit 10 has a body having a conduit wall 12. In this embodiment the conduit wall is a cylinder having uniform circular transverse section.

However, other embodiments may have any suitable

transverse section shape such as rectangular or

elliptical, for example. The conduit wall 12 defines a passageway 14 for disposing therein at least one

communications cable such as optical fibre cable 16 or electrical cable 18. The conduit may provide protection of the cables 16, 18 housed therein from trauma, moisture and corrosive elements, for example, especially when the conduit is varied. Disposed in the conduit wall is an electrical conductor 20. The conductor extends between the ends of the conduit. The conductor need not extend along the entire length, however. In this but not all embodiments, the conductor is longitudinally orientated and is

straight. In alternative embodiments, the conductor may generally have any configuration, such as a spiral or helical or even arbitrary configuration. The conductor may spiral around the passageway.

In the embodiments of figure 1, for example, the conductor is embedded in the wall so that it is, on the whole, not exposed. In an alternative embodiment, however the conductor is incorporated with the conduit wall such that the conductor is exposed along at least some of its length .

The conductor 20 is a stainless steel wire. In other embodiments a conductive ribbon may be used instead of the wire. Generally, any suitable form of conductor may be used. While the conductor 16 in this embodiment is a stainless steel, it may generally comprise any suitable metal such as copper, aluminium or any one of many metal alloys . Alternatively, another conductive material may be used such as composite material comprising a polymer having conducting particles of metal or carbon therein, or a conductive polymer. Generally any suitable conductive material may be used.

The wire 16 in this embodiment has a diameter of 0.9mm, however, any suitable diameter may be used, such as but not limited to a wire having a diameter in the range of 0.1mm to 1.5mm. Stainless steel is resistant to corrosion and is cheaper than copper.

The conduit wall is, in this embodiment, extruded high-density polyethylene such as HDPE 100 or HDPE 80. Alternative embodiments may be fabricated of polyvinyl chloride (PVC) or alternatively any other suitable polymer . The diameter of the conduit 10 in this embodiment is

100mm, however this diameter may be bigger or smaller in other embodiments as appropriate. Generally the conduit is not limited to any particular diameter. The conduit may be buried in the ground using one of several techniques. For example, a trench may be dug and 4m or 6m lengths of the conduit, for example, may be laid in the trench. The lengths may be joined together using sleeves or joiners, butt welded by heating ends that are then pushed together, or by using electrofusion welding.

In cases in which joiners are used, adjacent ends of adjacent lengths of conduit are inserted into a tight- fitting sleeve. An adhesive, for example Mastix, may be applied to the inside surface of the sleeve to promote the joining of the lengths. Lengths of conduit that are laid using this technique generally have a Class 6

specification as defined by Telstra Corporation. Alternatively, longer lengths (for example, 200m) of coiled conduit may be rolled out along a trench that is then backfilled.

In another alternative, a length of conduit is drilled into the earth using a directional drill method, where first a directional drill bit is attached to the earth-engaging end of the conduit. Generally a conduit buried using the directional drill method meet the Class 9 specification as defined by Telstra Corporation.

Once the conduit is buried it may then be made ready for connection with an electrical device. A section of conduit may be exposed by, for example, digging it out of the wall 12. Alternatively, a section of the wall may be abraded to expose the conductor 20. An electrical lead, for example, may then make electrical contact with the conductor 20. The other end of the lead may contact an electrical terminal or contact within a user-accessible pitt or other access point in readiness for connection with, for example, a signal generator. When a worker wishes to discover the conduit, he may remove the access cover to the pitt, and attach an activated generator that generates a radio signal to the terminal or contact in the pit. The signal, which may be a radio frequency electrical signal, for example, travels down the lead and into the conductor 20. In response the conductor emits a radio wave of corresponding frequency which can be detected using a radio signal detection unit swept over the conduit by a worker above the ground.

Generators and detection units are commercially available, an example of which is the Tracemaster II by Shonstedt USA. The detector unit may give, for example, a visible or audible alert when it is swept over the emitting conduit . During the installation of the conduit in the ground the ends of the conductor 20 may be dug out of the wall and electrically joined to the conductor of the adjacent length of conduit using a short piece of electrically insulated wire, for example, soldered in place. A jumper lead may alternatively be used or any other suitable electrical connection means. This allows the electrical signal to cross the junction between adjacent lengths and both lengths to emit detectable radio waves.

The communications cable conduit 10, and other embodiments of communications cable conduit, may be made using an extruder. A material, for example a polymer, is extruded through a die installed in the extruder. Raw thermoplastic material such as but not limited to high- density polyethylene in the form of small beads is gravity-fed into a barrel of the extruder. A rotating screw located in the barrel forces the plastic beads forward into the barrel which is heated to the desired melt temperature of the molten plastic. At the front of the barrel, the molten plastic leaves the screw and travels through a screen to remove any contaminants in the melt and then enters a die shaped to produce the conduit. The conduit is then cooled by pouring the recently extruded conduit through a water bath. The water bath may be sealed and acted upon by a controlled vacuum to keep the newly formed and still molten tube or pipe from collapsing .

The die is configured for extruding the conduit body. During the extrusion process, the conductor is

incorporated in the conduit body. A supplier of the conductor, for example a spool of wire, is arranged such that the wire is pulled off the spool by the material as it is extruded. Figure 2 shows a schematic view of one example of a section of a die 40 for making the communications cable conduit. Material enters the die at 42 and leaves through the annular space 44 defined by the die pin 46 and outer die annulus 48. Wire is inserted through port 50 and is drawn through the die by the material being extruded.

Figure 3 shows a photograph of an end of an example extruder 60 having the die of figure 2, and a wire 62 being pulled through the port 50 and die.

The material that is extruded may be any suitable material, such as a polymer material.

A cable can be installed in the conduit as follows. A string having one of its ends attached to a cable may have its other end blown through the cable. The end that has been blown through the cable or length thereof may then be pulled through by hand or with a capstan winch to draw the cable into the conduit.

Figure 4 shows a transverse section of a

communications cable conduit system generally indicated by the numeral 110. The system has a first communications cable conduit 112. A multi-passage communications conduit 114 is longitudinally disposed in a passageway 116 of the first cable conduit 112. The multi-passage communications conduit 114 has, in this embodiment, two cable receiving passages indicated by numerals 118 and 120 respectively. Each passageway 118, 120 connects opposite ends of the multi-passage cable conduit. The multi- passage communications cable need not be at the centre of the first communications cable conduit. Cables such as those indicated by numerals 122 to 126 may run along passageway 116 of the first communications conduit and further communications cables such as those indicated by numerals 128 and 130 may run along respective passageways oaf the multi-passage communications

conduit 114. In other embodiments of the system, the multi-passage communications conduit may have more than two cable receiving passageways, for example, three or four.

The cables 122 to 130 are, in this embodiment, optical fibre cables that form part of a communications network by a communication service provider such as, for example, Telstra™ or the Australian National Broadband

Network™. Cable 132, in this embodiment, is an electrical cable for carrying electronic data. Generally, any type of communications cable may be disposed in the

communications cable conduit system.

Generally, but not necessarily, the communications cable conduit system 110 is buried in the ground. The first communications conduit 112 may be, but is not limited to, high density polyethylene and have a diameter of 100mm. Other materials, such as polyvinyl chloride, and other diameters greater or less than 100mm may be used as appropriate. The first communications cable conduit may be installed by digging a trench and then laying 4m or 6m lengths, for example, of the conduit 112 which are subsequently attached end-to-end using one or more of an adhesive, joiners, butt welding, and electrofusion welding, for example. Generally the lengths may be joined using any suitable means . Alternatively, a relatively long length of the first conduit 110 may be supplied coiled. The coil may be rolled out along the length of the trench. The trench can then be filled in.

Alternatively, the first communications conduit 110 may be installed using known directional drill methods, where the conduit 110 acts as a drill shaft. A directional bit is first installed at the drilling end of the conduit to engage the earth.

Once the first communications conduit is installed by its owner, communications cables 122 to 126 may be disposed along the length of the first conduit. A string that is tied to one end of the cable to be installed is blown down the passage 116 of the first communications cable conduit 112. The far end that has been blown through the passageway 116 is then pulled either by hand or capstan winch, for example, drawing the cable to be installed through the passageway. This installation process may be repeated for each cable that is installed.

The owner, for example, may install the multi-passage communications cable conduit 114 in the first cable conduit 112. This may be performed, for example, some time after the installation of the first communications cable conduit 112 either before or or after cables 122 to 126 are installed. It may be suitable, however, to install the multi-passage communications cable conduit 112 at the same time as the first communications cable conduit is buried or otherwise installed.

To install the multi-passage communications cable conduit 112 in a preinstalled first communications cable conduit, a portion of the first cable conduit is exposed and an aperture formed in it. A long rod, say 150 metres but not necessarily so, is pushed through the apperature down the first cable conduit 110 with a rope, string or the like attached to one end. A multi-passage

communications cable conduit 114 is attached to the far end of the rope which is then drawn through the first passage communications cable conduit 112 by hand or capstan winch. This process may be repeated to install the required length of multi-passage communications cable conduit 114 within the first communications cable

conduit 112. Cable can then be installed in either one of passageways 118 and 120 of the multi-passage

communications cable conduit 114 using the blown string technique described above, or any suitable technique.

Generally, at least one of the first and multi- passage conduit meet the Class 6 or Class 9 conduit specifications as defined by Telstra Corporation of

Australia. These specifications define various physical properties of the conduit.

To join lengths of conduit, either the first or multi-passage conduits, the ends of adjacent conduits may be brought together and heated so that the ends soften and weld together. This is so-called butt welding. In another alternative, the ends of adjacent conduits may be inserted into a joiner or sleeve. The sleeve is generally an extremely tight fit to the joiners to provide a hold on the ends. A mastix adhesive may be first smeared on the inside surface of the joiners or ends of the conduits to enhance the grip of the joiner or sleeve on the conduit ends. Alternatively, electrofusion may be used.

Electrofussion is a method of joining high-density polyethylene and other plastic pipes using special fittings that have built-in electric heating elements which are used to weld the joint together. The pipes to be joined are cleaned, inserted into the electrofusion fitting, with a temporary clamp if required, and a voltage is applied for a fixed time depending on the fitting in use. The voltage is typically but not necessarily

40 volts. The built-in heater coils then melt the inside of the fitting and the outside of the pipe wall which weld together producing a very strong homogeneous joint. The assembly is then left to cool.

More than one multi-passage communications cable conduit may be installed in the first communications cable conduit. Accordingly, the diameter of the multi-passage communications cable conduit may be chosen to accommodate the space within the first communications cable conduit and the number of other multi-passage communications cable conduits and cables and other things within the first cable conduit.

The multi-passage communications cable conduit 112 may be manufactured by an extrusion process. Raw

thermoplastic material such as but not limited to high- density polyethylene in the form of small beads is gravity-fed into a barrel of the extruder. A rotating screw located in the barrel forces the plastic beads forward into the barrel which is heated to the desired melt temperature of the molten plastic. At the front of the barrel, the molten plastic leaves the screw and travels through a screen to remove any contaminants in the melt and then enters a die shaped to produce the conduit. The conduit is then cooled by pouring the recently extruded conduit through a water bath. The water bath may be sealed and acted upon by a controlled vacuum to keep the newly formed and still molten tube or pipe from collapsing. The die may have a pin or mandrel of the appropriate configuration for forming the passageways.

For tubing with multiple passageways the die may have more than one pin or mandrel. The die used to make the multi- passage conduit shown in the figures comprises two mandrels, each having a shape complementary to a

respective one of the passageways. Each mandrel presents an area shaped as a portion of a circle cut by a chord.

Figure 5 shows a schematic view of one example of a section of a die 140 for making the communications cable conduit. Material enters the die at 142 and leaves through the annular space 44 defined by the die pin 146 and outer die annulus 148. The pin has a slot 150 which divides the pin into the two mandrels 152 and 154.

Material enters the slot during the extrusion process.

An embodiment of a multi-passage cable conduit that is formed has an extruded body comprising an outer wall and an inner wall disposed longitudinally within the outer wall to form the two or more passageways. The inner wall is disposed within the outer wall to form two passageways of substantially equal transverse area, at least in the embodiment shown in Figure 4. The wall extends between opposing interior surface portions of the outer wall. For example, the wall extends along a diameter of the conduit. Generally, the conduit is cylindrical but may be of any suitable geometry such as square, rectangular or

elliptical. Each passageway of the multi-passage conduit may be described as having a transverse section shaped as a portion of a circle cut by a chord.

Now that embodiments have been described, it will be appreciated that some embodiments have some of the following advantages:

• multiple passages may enable better cable

organization and management;

• cables may be manipulated without affecting or

inadvertently damaging the cables in the other passage;

• the passages may be made available, for example,

sold, leased or rented, to a third party;

• each passageway may be provided to a different party;

• the multi-passage communications cable conduit can be installed in a previously installed communications cable conduit, as required, without requiring the digging of trenches . Consequently, a second party may be able to install their own cable conduit within another's without the expense of digging trenches;

• in some circumstances, the first conduit may be owned by one party who leases or sells access to the first conduit to allow a third party to install a conduit to run communication cables. By installing a multi- passage communication conduit rather than a single passage conduit, the third party may be able to supplement its installed communication cables at a later date by access to a free passage in its multi- passage conduit rather than having to install a further conduit in the first conduit (which would typically incur additional payment to the owner of the first conduit) as would have been the case if it had installed a single passage conduit.

It will be appreciated that numerous variations and/or modifications may be made to the invention as shown in the specific embodiments without departing from the spirit or scope of the invention as broadly described. For example, the conduit body may incorporate one or more internal features, such as an extruded longitudinal rib, having the conductor therein or thereon. The rib may be fixed to an internal surface of the conduit wall.

Alternatively, the rib may be fixed to an external surface of the conduit wall. The present embodiments are, therefore, to be considered in all respects as

illustrative and not restrictive.

In the claims which follow and in the preceding description of the invention, except where the context requires otherwise due to express language or necessary implication, the word "comprise" or variations such as "comprises" or "comprising" is used in an inclusive sense, i.e. to specify the presence of the stated features but not to preclude the presence or addition of further features in various embodiments of the invention.

It is to be understood that, if any prior art publication is referred to herein, such reference does not constitute an admission that the publication forms a part of the common general knowledge in the art, in Australia or any other country.

Claims

1. A communications cable conduit comprising:

an electrical conductor, the conductor is for receiving an electrical signal and emitting

detectable electromagnetic radiation for discovery of the conduit.

2. A communications cable conduit defined by claim 1 wherein the conductor is incorporated with the body.

3. A communications cable conduit defined by either one of claim 1 and claim 2 wherein the conductor is embedded in a conduit wall.

4. A method of making a communications cable conduit defined by any one of the Claims 1 to 3, the method comprising the step of extruding a material through a die configured to shape the material in the form of a body of the communications cable conduit.

5. An apparatus for making a communications cable

conduit defined by any one of the Claims 1 to 3, the apparatus comprising:

a supplier of conductor arranged to co-operate with the die such that the conductor can be drawn through the die during the extrusion process and incorporated with the body.

6. A communications cable conduit system comprising: a first communications cable conduit; and a multi-passage communications cable conduit that is longitudinally disposed in the first

communications cable conduit, the multi-passage communications cable conduit having at least two communications cable receiving passageways, each passageway connecting opposite ends of the multi- passage communications cable conduit.

7. A method of installing a communications cable conduit system, the method comprising the step of:

disposing a multi-passage communications cable conduit longitudinally in a first communications cable protecting conduit, the multi-passage

communications cable conduit having at least two communications cable receiving passageways, each passageway connecting opposite ends of the multi- passage communications cable conduit.

8. A method of manufacturing a multi-passage

communications conduit, the method comprising the steps of:

passing an extrudable material through an extrusion die configured for extruding a multi- passage communications cable conduit having at least two passageways, each passageway connecting opposite ends of the multi-passage communications cable conduit .

9. A method of installing communications cables, the method comprising the steps of:

installing a communications cable conduit system defined by claim 3; and disposing one or more communications cables in at least one of the communications cable receiving passageways .

A multi-passage communications cable conduit comprising an extruded body having an outer wall and an inner wall disposed longitudinally within the outer wall to form two communications cable receiving passageways, each passageway connecting opposite ends of the conduit.