WO2017167319A1

WO2017167319A1 - Combined power cable

Info

Publication number: WO2017167319A1
Application number: PCT/CZ2017/000018
Authority: WO
Inventors: Jaroslav TROJAN
Original assignee: Predistribuce, A.S.
Priority date: 2016-03-31
Filing date: 2017-03-28
Publication date: 2017-10-05
Also published as: PL127833U1; SK8517Y1; CZ2016185A3; SK500892018U1; DE212017000024U1; PL71351Y1

Abstract

A combined power cable containing at least three power wires (11) and a tube (1) for optical-fibre cable, especially a combined power cable (10) for low-tension networks up to 1 kV where the cross section of the power wires (11) has the shape of an annular sector and where the inner diameter of this annulus corresponds to the outer diameter of the tube (1) and where the power wires (11) surround the tube (1) for the optical-fibre cable thus ensuring its stabilized position in the centre of the combined power cable (10).

Description

Combined Power Cable

Technical Field

The invention concerns an electric cable, especially an electric cable for low- voltage (LV) distribution networks (1 kV) and for data transmission.

State of the Art

When designing new LV (low-voltage) networks, which generally means networks up to 1 kV, it is necessary to take into consideration the type of the existing housing or industrial development in the given location. As further demand for the relating services in future is rather difficult to estimate, it is economical (taking the earthwork expenses and the price of the cables into account) to use a 1 kV cable (e.g. 1-AYKY-J 3 x 240 + 120). Because of new requirements for better electricity distribution control, and due to the requirements following out of the new EU data collection and data control legislature (within the bounds of power distribution), creation of data communication systems closely bound to the distribution network control will be required in future. In order to ensure the interconnected data flows, a sleeve of high-density polyethylene (HDPE) is usually laid into the buried line. The outer diameter of the sleeve is 40 mm and it forms a physical layer, i.e. a kind of cable duct to facilitate an optic cable (with single-mode optical fibres) to be blown in. Thus, the desirable data transfer for signalling and control is ensured. This type of data communication is mainly used in order to form a core control network. Taking into account the existing legislature or other limiting conditions, it often happens that this type of cable instattation cannot be carried out.

Patent document CH 6665047 also describes a high-voltage cable which contains three wires with a tube arranged in the centre. The tube may serve as an optical-fibre duct. A disadvantage of this design is the fact that the cross-section of the wires is circular. Due to this fact, the tube is guided in three points (seen in its cross- section) or, in reality, in three contact lines along its length. For that reason, the tube is not stabilized in position. It may therefore happen that the tube is pushed out of its centre position. When the cable is bent, two of the wires may be shifted a little along the surface of the third wire thus creating a gap in which the tube may be locked, caught and pinched. In such a case, no cable or fibre blowing is possible. The goal of the invention is to solve the technical problem that consists of guiding the tube for optical fibres in such a manner that the optical fibre can be easily, quickly and smoothly blown in the tube in any situation.

Principle of the Invention

The aforementioned weaknesses are, to a large extent, eliminated and the goals of the inventions accomplished by a combined power cable which contains at least three non-circular power wires and a tube for an optical-fibre cable, especially by a combined power cable for low-voltage (up to 1 kV) networks according to the invention the nature of which consists in the fact that the cross-sections of the power wires are annular-sector-shaped (i.e. the cross sections of the power wires have the shape of an annular sector) where the inner diameter of this annulus corresponds to the outer diameter of the tube. Thus the power wires surround the tube for the optical-fibre cable completely ensuring its stabilized position in the centre of the combined power cable. The cable formed according to this invention is suitable for conducting both power current and data flow.

A particularly advantageous arrangement of the power cable according to this invention is its arrangement with three power wires and one protective wire surrounding the tube where the cross-sections of the power wires and of the protective wire are annular-sector-shaped (i.e. the cross sections of the power wires and of the protective wire have the shape of an annular sector) and where the inner diameter of this annulus corresponds to the outer diameter of the tube while the outer diameter of the annulus, in essence, corresponds to the outer diameter of the cable before being wrapped with outer insulating layer. As specialists in this field know, wires in a power cable are surrounded with at least one layer of outer insulation which forms the outside surface of the power cable and so the overall diameter of the combined power cable is given by its diameter including the outer insulation layer. A particularly advantageous arrangement of the power cable according to this invention is its arrangement with a tube whose outer diameter is 10 mm because this outer diameter of the tube facilitates making the power cable without any fundamental changes in its outer diameter. Another advantageous version/design of the combined power cable according to this invention contains a tube provided with seals at its ends to prevent moisture from getting in the tube. Before blowing the cable into the tube, the seals must be removed. In its advantageous design, the tube is made of a non-flammable material, and in the most advantageous design, it is made of high-density polypropylene (HDPP) on the understanding that the tube is adapted for installation of optical cables and of bunched optical fibres (so-called "microfibres"). It is also advantageous if the tube is provided with a non-flammable insulation layer. The main function of the tube is to protect the cables and bunched optical fibres from mechanical damage. The most common method of inserting the cable in the tube is the so-called "blowing" method using compressed air. Another option is pulling the cable through the tube manually.

It is extremely advantageous if the tube is provided with shaped elements inside to decrease friction during blowing the optical cable in and out.

An advantage of the combined power cable according to this invention is (apart from other things) also the saving of cost in comparison with the laying of the HDPE sleeve along the cable line to protect the data flow. The saving applies to the project itself, to the relating legislature as well as to the cost of implementation of the project. The combined power cable facilitates carrying out data flows not only when new networks are built or larger modernizations made but also when an insufficient or damaged section of the existing low-voltage cable is to be replaced by a new one. In such a case, using the combined power cable according to this invention is extremely advantageous.

There exist several lengths of the combined power cable according to this invention that can be connected one to another to create the length required. This is possible by dint of the respective mutual interconnection of the tubes serving for blowing the cable in. In this case, the structure of the combined power cable provides the tube with the necessary mechanical protection thanks to the wires that surround the tube. In this way, the optical cable is sufficiently protected from being damaged. Both the tube and the optical cable are dielectric. For data communication over optical fibres, 1310 nm and 1550 nm wavelength lasers are used nowadays. This type of communication does not affect operation of low-voltage power cables, particularly not with the voltage of 1 kV which is considered to be used most often with the combined power cable according to this invention. And vice versa, the electric current flowing through the power wires does not affect the data operation over optical fibres passing through the tube in the centre of the combined power cable according to this invention. Overview of the Figures

The invention will be better understandable from the examples of the designs of the invention and from the figures attached hereto where Fig. 1 shows a sectional view of the combined power cable according to the advantageous arrangement of this invention.

Examples of the Performance of the Invention

In the following example of designs, the combined power cable according to this invention is introduced as a cable for low-voltage (1 kV) distribution networks.

Fig. 1 shows a sectional view of the combined power cable for 1 kV. In this Figure, the combined power cable 10 contains a non-flammable tube 1 of high-density polypropylene (HDPP) in its centre into which the optical-fibre cable can be inserted. The tube may possibly be provided with a non-flammable insulation layer. The tube 1 is provided with shaped elements inside (not shown in the Figure) to decrease friction during blowing the optical cable in and out. The outer diameter of the tube 1 is 10 mm. An especially advantageous method of inserting the cable in the tube 1 is the so-called "blowing" method using compressed air. This method of optical cable insertion is well known among experts in this field. The tube 1 is arranged in the centre along the whole length of the combined power cable 10 and it is surrounded with three power wires J and with one earth/protective wire 12 in the shape of annular sectors which, altogether, form an annulus in the centre of which the tube 1 is arranged. In the example of the design shown in Fig. 1 , three power wires H and one earth/protective wire 2 are arranged around the tube 1 on the understanding that a higher or lower number of the power wires can be used if required so.

The outside surface of the power wires V_ and of the earth/protective wire 12 is wound around with a tape (not shown) which is then wrapped around with an outside insulation layer 13.

According to the design not represented in the Figure, the combined power cable can only contain the three power wires H and the tube 1 for the optical-fibre cable where the cross sections of the power wires H are annular-sector-shaped (i.e. the cross sections of the power wires and of the protective wire have the shape of an annular sector) and where the inner diameter of this annulus corresponds to the outer diameter of the tube 1 Thus the power wires surround the tube 1 for the optical-fibre cable completely ensuring its stabilized position in the centre of the combined power cable 10. The outer diameter of the tube is 10 mm.

According to both the designs/variants, the tube \ is provided with seals (not shown) at its ends to prevent moisture from getting in the tube i before the cable is placed into it.

It is also obvious to experts in this field that although Fig. 1 shows the design/variant of the combined power cable with three power lines H of the same cross section while the cross section of the earth/protective wire is smaller, any other designs/variants are well possible, e.g. the earth/protective wire 12 can have the same cross section as the power wires or the cross sections of the wires can differ if required so. A design with a number of wires higher than four is also possible. An advantage of the combined power cable according to this invention is the fact that the wire (or wires as the case may be) in the combined power cable according to this invention actually serve as spacers holding the tube in the given position in any situation, e.g. when winding the cable on the drum during its manufacture or transportation or when laying the cable in the place of destination. Thanks to the wires surrounding the tube, it is ensured that the tube will not be damaged and that it will remain passable for the optical-fibre cable whenever it is necessary.

The construction of the combined power cable facilitates quick and easy repairs of the tube in case of any damage of the power cable using a coupling method.

The combined power cable according to this invention also influences methods of its connection to a distribution box. When connecting the combined power cable to a distribution box, the power part of the cable is (after the insulation is removed frorrv the ends of individual wires) is separated from the tube and the tube is then led out of the power part. To ensure smooth insertion of the optical-fibre cable into the tube, the inside of the tube should be protected with seals at both its ends to prevent the tube from getting moisture into it. industrial Application

The combined power cable according to this invention can be used for electric current conduction and data flow conduction simultaneously. List of Reference Marks tube

combined power cable power wire protective wire outer insulation layer

Claims

Patent Claims

1. A combined power cable containing at least three power wires (11) and a tube (1) for optical-fibre cable, especially a combined power cable (10) for low- tension networks up to 1 kV characterized in that a cross section of the power wires (11) has the shape of an annular sector where the inner diameter of this annulus corresponds to the outer diameter of the tube (1) and that the power wires (11) surround the tube (1) for the optical-fibre cable thus ensuring its stabilized position in a centre of the combined power cable (10).

2. The combined power cable according to Claim 1 characterized in that the tube (1) is surrounded by three power wires (11) and one protective wire (12) and that the cross sections of these wires (11 ,12) have the shape of an annular sector where the inner diameter of this annulus corresponds to the outer diameter of the tube (1) while the outer diameter of this annulus, in essence, corresponds to the outer diameter of the combined power cable (10) before it is wrapped with the outer insulation layer (13).

3. The combined power cable according to any of Claims 1 and 2 characterized in that the inner diameter of the tube (1) is 10 mm.

4. The combined power cable according to any of Claims 1 through 3 characterized in that the tube (1) is provided with seals at both its ends to prevent moisture from getting in.

5. The combined power cable according to any of Claims 1 through 4 characterized in that the tube (1) is made of a non-flammable material.

6. The combined power cable according to any of Claims 1 through 5 characterized in that the tube (1) is provided with a non-flammable insulation layer.

7. The combined power cable according to any of Claims 1 through 6 characterized in that the tube (1) is provided with shaped elements inside to decrease friction.

8. The combined power cable according to any of Claims 1 through 6 characterized in that the tube (1) is made of high-density polypropylene (HDPP).