Classifications

• • H—ELECTRICITY
  • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
  • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
  • H05K9/00—Screening of apparatus or components against electric or magnetic fields
  • H05K9/0007—Casings
  • H05K9/0018—Casings with provisions to reduce aperture leakages in walls, e.g. terminals, connectors, cables
• • 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
  • H02G3/00—Installations of electric cables or lines or protective tubing therefor in or on buildings, equivalent structures or vehicles
  • H02G3/22—Installations of cables or lines through walls, floors or ceilings, e.g. into buildings

Definitions

• the invention relates to a sealing system comprising at least one cable and at least two sealing rings at least in part made of an elastic material, which sealing rings are arranged round the cable in spaced-apart relationship for sealing confinement of the cable by collaring the same in a bushing extending co-axially with the sa-ble.
• Such a sealing system is generally known.
• an air space is present between the sealing rings, which air space is bounded by the bushing and, as already said before, the sealing rings.
• the excellent thermal insulation properties of said air space prevent the other side of the bushing becoming (too) hot for some time.
• the object of the invention is to improve the prior art sealing system in the sense that a high-quality, fire resistant, gas and liquid-tight sealing system is proposed, which system is furthermore optimally protected against electromagnetic overtension and/or interference.
• a sealing system of the kind referred to in the introduction is characterized in that the sealing system comprises an electrically conducting material which is present in a passage formed between the cable and the bushing, and which is in contact with an electrically conducting braiding of said at least one cable in the operative condition, earthing said braiding electrically.
• Electric installations and machines in which highly sensitive components are generally used, for example for control and registration purposes, are liable to interference from various external electromagnetic fields and pulses.
• Said external electromagnetic fields and pulses may be generated by, for example, radar installations, thunderstorms, nuclear explosions and electric equipment.
• steel structures which function as a Faraday cage, are frequently placed round a space intended for accommodating electronic equipment, so as to reduce such interference.
• Electric cables which are led into such a shielded space, may conduct undesirable electromagnetic fields and pulses into the electronic equipment yet, however. As a rule, this conduction will take place across the electrically conducting braiding of the cables in question that are being led through.
• said external, undesirable electromagnetic fields and pulses can flow away to earth via the electrically conducting braiding of a cable being led through.
• the term “cable” is understood to include an electrically conductive conduit, tube, pipe of the like, for example a metallic tube or pipe, with the present electrically conductive material being in electrically conductive contact therewith in the operative condition.
• the electrically conductive material comprises an electrically conductive tape.
• said electrically conductive tape is-.at least partially wound round the electrically conductive cable braiding in the operative condition.
• the electrically conductive tape is wound round the electrically conductive cable braiding near one end, whilst it is attached to the electrically conductive bushing (which is made of a metal, for example) fitted in, for example, an opening in a wall, being in electrically conductive contact therewith, near its other end.
• the earthing of the electrically conductive cable braiding by means of the electrically conductive material has been effected by selecting several pieces of electrically conductive tape material, whether or not folded together and/or several electrically conductive sleeve means or hose members arranged in said passage as the electrically conductive material, which sleeve means preferably extend in the same direction as said at least one cable .
• the electrically conductive tape and/or the electrically conductive sleeve means is/are at least substantially made of an electrically conductive rubber.
• Said rubber has been made electrically conductive in particular by chemical means, in particular by the addition thereto of carbon particles, preferably in the form of carbon black.
• said rubber is EPDM rubber, whilst said carbon particles are preferably concave shell-shaped, especially of the type "Ketjenblack EC" 300J or 600 JD TM.
• EPDM stands for Ethylene/Propylene/Diene/Monomer . It is noted that also other elastomers or plastomers can be used as materials for said tape and said sleeve means.
• the electrically conductive tape is a metal tape.
• the electrically conductive (rubber or metal) tape is flexible, that is, deformable, so that it can readily be led along other cables that are being led through the bushing.
• the electrically conductive tape has a contact width of at least about 20 mm, preferably about 40 mm.
• the tape is usually used for civil applications (attenuation factor -30 dB) , whilst a contact width of more than 100 mm (attenuation factor -60 dB) can be used for military applications.
• an optimum electrically conductive contact is effected so as to prevent electromagnetic overtension and/or interference .
• said electrically conductive material comprises a moulding paste, for example in the form of an injectable putty, in which the composition substantially consists of a binding agent and an electrically conductive component, in such an amount that the electromagnetic interference measurement in accordance with the EMC IEC 11.9.1 standard in the range between 30 MHz to 1 GHz will show a signal attenuation of at least >-60 dB .
• said binder has been selected from the group of elastomers, preferably silicones, and said electrically conductive material is carbon-based, preferably expandable graphite, since this form of graphite also exhibits fire-resistance.
• Said binder and said form of carbon are advantageous with a view to achieving low resistance values and a good viscosity. More preferably, oil and/or other agents, such as anti-static agents and viscosity- reducing agents, are added, as a result of which in particular a good workability is obtained.
• the invention provides a moulding paste which exhibits a suitable viscosity, so that the moulding paste is injectable, thus being suitable for a wide range of applications, and which has a surprisingly low resistance value.
• the moulding paste according to one preferred embodiment of the invention will be marketed under the name of CONDUCTON ® , which is a brand name of Beele Engineering B.V.
• Said CONDUCTON ⁇ moulding paste has additional properties: - specific weight 1.4 ⁇ 0.03 g/cm 3 tensile strength 0.8 MPa elongation at break 40% hardness 30 Shore A elasticity approx. 25% and in addition it adheres--well to metal surfaces, such as steel, zinc and copper.
• the resistance value of CONDUCTON ® moulding paste is less than 100 ohms, and in addition it is water repellent.
• the sealing rings comprise circular outer ribs and circular inner ribs, which outer ribs have an outside diameter which is larger than the inside diameter of the bushing, and in which the inside diameter of the inner ribs is at most at least substantially the same as the outside diameter of the cable.
• the sealing rings each comprise at least two shell members, whose abutting boundary surfaces extend at least substantially in axial direction, and the rear flanks, seen in the direction of insertion, of the outer, serrated ribs extend in radial direction whilst the inner ribs are arranged in pairs in the radial area of the outwardly extending tips of the outer serrated ribs.
• the inner ribs of the sealing rings are preferably trapezoidal in shape, seen in the direction of the axial longitudinal section.
• the spacing between the sealing rings is less than 25 mm, in which said sealing rings comprise an expandable material, in an amount and of a composition such that the sealing rings will expand in the case of a fire, to such an extent that they will wedge themselves in the bushing.
• the spacing .between the sealing rings is less than 120 mm, in particular about 40 mm.
• FIG 1 shows an opening 1 in a wall 2, in which a steel bushing 3 is fitted.
• a tape 10 of EPDM rubber on a winding roll 9 is used, which tape has been made electrically conductive by the chemical addition of carbon particles (for example carbon black particles) thereto, which tape is to be wound round the electrically conductive braiding 8.
• the tape 10 preferably has a width of 40 mm, so that an optimum electrically conductive contact with said electrically conductive braiding 8 is realised.
• the electrical earthing is ensured by winding the tape 10 to a diameter larger than that of cables 4, 5, 6, as is shown in Figure 1 and as will be explained in more detail yet.
• hose members 11 of an electrically conductive material are placed in the passage formed between the bushing 3 and the cables 4, 5, 6, whilst it is also possible to use folded-together pieces 12 of the tape 10 in addition thereto or instead thereof.
• the hose members 11 are made of the same electrically conductive material as the tape 10, viz. of EPDM rubber which has been made electrically conductive by the addition of carbon particles, the electrically conductive braiding 8 is connected, being earthed electrically, to the steel bushing 3 via the tape 10 and the hose members 11 and/or the pieces of tape 12.
• the tape 10 has been wound to a diameter larger than that of the cables 4, 5, 6 so as to guarantee the electrically conductive contact between the tape 10 and the hose members 11.
• Figure 3 corresponds to Figure 2, with this difference that an electrically conductive moulding paste 13 is used instead of the hose members 11 and/or the pieces of tape 12 so as to effect electrical conduction between the (electrically conductive braiding 8 of the) cables 4, 5 and 6 and the electrically conductive (steel) bushing 3.
• an electrically conductive moulding paste 13 is used instead of the hose members 11 and/or the pieces of tape 12 so as to effect electrical conduction between the (electrically conductive braiding 8 of the) cables 4, 5 and 6 and the electrically conductive (steel) bushing 3.
• the electrical conductivity of a moulding paste according to the invention was measured by experiment.
• the electrical resistance was less than 1,000 ohms at all times, and preferably less than 100 ohms.
• the resistance values were determined in accordance with ISO 2878 standard methods in all cases.
• FIG. 1 A sample plate dimensioned 100 x 100 x 10 mm was used for determining the resistance value.
• Figure 4 shows how the bushing 3 is sealed, both in the preferred variant of Figure 3 and in the one of Figure 2, by fitting sealing rings 14 round the cable 4 on either side for sealing confinement of the cable through collaring in the bushing 3 that extends co-axially therewith.
• the sealing rings 14 are fitted in spaced-apart relationship round the cable 4 in the passage 15 between the cable 4 and the bushing 3, so as to confine the cable 4 in the bushing 3 in a gastight and watertight manner.
• the bushing 3 is fitted in a steel ship's deck, a wall, a partition, or the like.
• Each sealing ring 14 made of a resilient rubber is preferably formed by two identical, shell-shaped ring halves 14', 14'', the abutting boundaries surfaces of which extend in axial direction.
• the ring halves 14', 14' have ribs 16 of right- angled triangular cross-section on the outer side and trapezoidal ribs 17 on the inner side.
• an expandable material for the sealing rings 14 in such an amount and of such a composition that the sealing rings 14 will expand to such an extent in the case of a fire that the sealing rings will wedge themselves in the bushing 3.
• the thermally insulating properties of the air space 18 that may be present will be retained in the case of a fire, whilst the risk of a pressure build-up of such a magnitude that the sealing rings 14 will be forced out of the passage 15 is ruled out under all circumstances.
• the sealing rings will be forced out a few millimetres, that is, over a width of one or more ribs 17, but the original position of the sealing rings, and thus their sealing function, will be substantially retained in such a case.
• the expandable rubber material of the sealing rings 14 in particular comprises expandable graphite. Experiments have shown that said graphite is excellently suitable for causing the sealing rings 14 to expand in the case of a fire.

Landscapes

• Engineering & Computer Science (AREA)
• Architecture (AREA)
• Civil Engineering (AREA)
• Structural Engineering (AREA)
• Microelectronics & Electronic Packaging (AREA)
• Installation Of Indoor Wiring (AREA)
• Shielding Devices Or Components To Electric Or Magnetic Fields (AREA)

Applications Claiming Priority (3)

Publications (1)

Family

ID=19773526

Family Applications (1)

Country Status (3)

Families Citing this family (2)

Family Cites Families (3)

• 2001
  • 2001-06-12 NL NL1018262A patent/NL1018262C2/nl not_active IP Right Cessation
• 2002
  • 2002-06-03 EP EP02741516A patent/EP1407524A1/de not_active Withdrawn
  • 2002-06-03 WO PCT/NL2002/000360 patent/WO2002101898A1/en not_active Application Discontinuation

Non-Patent Citations (1)

Also Published As

Similar Documents

Legal Events