Classifications

• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
  • H01B7/00—Insulated conductors or cables characterised by their form
  • H01B7/36—Insulated conductors or cables characterised by their form with distinguishing or length marks
  • H01B7/361—Insulated conductors or cables characterised by their form with distinguishing or length marks being the colour of the insulation or conductor
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
  • H01B9/00—Power cables
  • H01B9/02—Power cables with screens or conductive layers, e.g. for avoiding large potential gradients
  • H01B9/028—Power cables with screens or conductive layers, e.g. for avoiding large potential gradients with screen grounding means, e.g. drain wires

Definitions

• the present invention refers to a contrivance at mains cables for shielding the cables from radiation of electric alternating fields.
• Every unscreened mains cable is radiating an electric alternating field. This field influences other electric equipment in its surrounding. For example, we get hum in our hifi equipments if we do not screen the low signal interconnect cables. We get disturbances in data transference and process controllers if we do not screen the transmission cables and sensitive parts of the equipment. Disturbances may as well emanate from transients on the mains net work, caused by other mains equipment, for example thyristor controlled lamps and machines.
• exisiting screened mains cables are constructed as an ordinary 3-conductor mains cable, but provided with an exterior screen of aluminum foil and inside this aluminum screen there is a naked wire in contact with the screen, along the entire cable. This naked wire serves as a screen connection conductor.
• the main purpose with the present invention is to achieve a contrivance regarding mains cables that enables a screening of the cable without the additional screen connection conductor, and that the cable can be handled as any ordinary mains cable.
• the mentioned purpose is achieved by means of a contrivance in accordance with the present invention which is mainly characterized in that between fields of insulation arranged to encircle an earth conductor which is received on the inside of an along the entire cable running screen, an electric conductor is received, which is arranged to connect the earth conductor with the mentioned cable screen.
• a variant of the invention is characterized in that a jacket preferably made of a multi-coloured, for example green/yellow, electrically semiconductive or conductive mixture of polymers, which for example is formed by additive polymer materials, is extending around an earth conductor, which is received on the inside of an along the cable extending cable screen, which earth conductor jacket is arranged so as to connect the earth conductor with said surrounding cable screen.
• a jacket preferably made of a multi-coloured, for example green/yellow, electrically semiconductive or conductive mixture of polymers, which for example is formed by additive polymer materials, is extending around an earth conductor, which is received on the inside of an along the cable extending cable screen, which earth conductor jacket is arranged so as to connect the earth conductor with said surrounding cable screen.
• Fig. 1 shows a cross sectional view of a screened mains installation cable in accordance with the present invention and which comprises three conductors,
• Fig. 2 shows a perspective view of an earth conductor in accordance with the invention
• Fig. 3 shows a variant of a screened mains installation cable in cross section.
• This marking line consists of semi- conductive plastic.
• This marking line constitutes a connection between the earth conductor and the surface of the insula ⁇ tion along the line, which in its turn is in contact with the screen. In this way we have got an automatic screen connection.
• the screen connection surface of the semiconductive plastic is consid- erably larger than the surface that might touch another current carrying component or touch a part of the human body, and thus enabling the semiconductive plastic to keep a high value of Ohm x meter.
• the purpose is to adapt the conduct ⁇ ivity of the semiconductive plastic down to a level of harm- lessness which can be approved by SEMKO after exemption from the authorities of electric safety.
• the cable is also to be secured against interior electric surge breakdown.
• PVC insulation can exhibit pores that go all the way through and such pores might cause electric surge breakdown. Therefore, an insula ⁇ tion similar to the insulation of the two other conductors is required also on the earth conductor.
• the periphery of the earth conductor of our cable is not entirely PVC insulated owing to the semiconductive line. This is solved by putting a double insulation on each of the two current carrying conductors instead. Then the probability of two through- going pores in contact with each other remains equally small.
• a contriv- ance 1 at a mains cable 2 which is meant to make a screen ⁇ ing of the cable from electric alternating field, what is called the E-field, is designed in such a way that between fields 3, 4 of electric insulation, which is arranged to encircle an earth conductor 5, for example a common concen- trie multistrand copper conductor with strand diameter and oh ic resistance in compliance with the regulations, and which is interiorly received in a tube shaped cavity 6 in an along the cable 2 extending connecting screen 7, a conductor 8, 9 is received, which is arranged to connect the earth conductor 5 with the surface 10A of its insulation 10, for conductive connection with said connecting screen 7 of the mains cable 2.
• an earth conductor 5 for example a common concen- trie multistrand copper conductor with strand diameter and oh ic resistance in compliance with the regulations
• said conductor 8, 9 preferably consists of semiconductive plastic which can be designed as a sector shaped line extending to the connecting surface between the earth conductor 5 and the insulation 10 along ⁇ side the line 8, 9.
• connection conductors 8, 9, which preferably are two conductors located opposite each other on the earth conductor 5, run helically around the earth conductor 5.
• Said insulation 3, 4 is made of plastic material, preferably PVC and more exactly comprising two differently coloured fields 3, 4 of insulation, green/yellow which lenghtwise are limited by the connection conductors 8, 9 along lateral edges 8A, 8B, 9A, 9B, respectively, extend ⁇ ing along the earth conductor 5 for surface connection with the lateral edges 3A, 3B, 4A, 4B of the insulation fields 3, 4.
• the intermediate connnection conductors 8, 9 are black coloured.
• the earth conductor 5 as well as additional conductors 11, 12 can be surrounded by individual layers 13, 14 of insulation, preferably with double layers 13, 13A; 14, 14A of PVC.
• a semiconductive nylon screen 7 preferably forms a cable screen exteriorly around all the conductors 5, 11, 12, and the conductors 5, 11, 12, which are evenly distributed inside the semiconductive nylon screen 7, are also surrounded by an around said nylon screen 7 extending, exterior insulating jacket 15 of electrically insulating material, preferably of PVC.
• the contrivance 101 at a mains cable 102 which is intended for screening of the cable from electric alternating field, comprises a jacket 150 extending around an earth conductor 105, which is received interiorly in a cable screen 107 extending along the cable 102, which jacket 150 is preferably made of multi ⁇ coloured, for example green/yellow, electrically semicon ⁇ ductive or conductive polymers, i.e. plastic.
• Said plastic is formed by polymer materials, preferably PVC containing for example a number of organic additives in order to obtain the desired properties of electric conductivity as well as the wanted colour of the product.
• Said jacket 150 of the earth conductor is likewise arranged so as to via connecting surface 151 between screen 107 and electrically conductive or semiconductive jacket 150 electrically connect the earth conductor 105 with said cable screen 107.
• this cable 102 may exhibit an electri ⁇ cally semiconductive nylon screen 107 forming a cable screen exteriorly around the earth conductor 105 and two conductors 111, 112.
• said conductors 105, 111, 112 which are evenly distributed inside the semiconductive nylon screen 107, may also be surrounded by an around said nylon screen 107 extending exterior insulating jacket 115, prefer ⁇ ably made of PVC.
• Cables exhibiting the desired properties can be produced for example by adding suitable additives to the electrically conductive or semiconductive polymer material in question which is possible to colour.
• suitable additives i.e. concerning electric conductivity and colour
• one example is to add compounds with the designation CEE 0841 and CEE 0851, respectively, from the company Borealis Compounds AB.
• the design is that a semiconductive nylon screen surrounds a mains cable with three conductors, where the earth conductor is not insulated, but provided with a jacket of yellow/green semiconductive plastic. The yellow/ green plastic bears against the screen, whereby the screen is automatically connected.
• the bending fatigue limit of the nylon screen is far higher than that of a common copper twist. Also the environmental immunity is higher as far as the capacitive influence of humidity is concerned, and also the interference immunity is higher.
• the idea of the invention is to colour it yellow/green and in this way automatize the screen connec ⁇ tion and still comply with the requirements.
• a screened cable where it is not necessary to connect the screen by means of a separate secondary conductor, but which is automatically screened by means of the yellow/green earth conductor.
• the very idea of the invention is t h e use of yellow/green coloured semicon d uctive plastic.
• this can b e solve d b y means of a double insulation of the two current carrying conductors.

Landscapes

• Communication Cables (AREA)
• Insulated Conductors (AREA)
• Laying Of Electric Cables Or Lines Outside (AREA)
• Measuring Leads Or Probes (AREA)

Priority Applications (3)

Applications Claiming Priority (2)

Publications (1)

Family

ID=20393096

Family Applications (1)

Country Status (7)

Cited By (2)

Citations (4)

• 1994
  • 1994-02-25 SE SE9400670A patent/SE503975C2/sv not_active IP Right Cessation
  • 1994-08-10 TW TW083107284A patent/TW247366B/zh active
• 1995
  • 1995-02-24 AT AT95910849T patent/ATE187576T1/de not_active IP Right Cessation
  • 1995-02-24 DE DE69513807T patent/DE69513807T2/de not_active Expired - Lifetime
  • 1995-02-24 WO PCT/SE1995/000202 patent/WO1995023418A1/en active IP Right Grant
  • 1995-02-24 EP EP95910849A patent/EP0746858B1/de not_active Expired - Lifetime
  • 1995-02-24 AU AU18660/95A patent/AU1866095A/en not_active Abandoned

Patent Citations (4)

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