CN2789892Y

CN2789892Y - Three-coaxial cable

Info

Publication number: CN2789892Y
Application number: CN 200320115865
Authority: CN
Inventors: 黄叙银
Original assignee: Individual
Current assignee: Individual
Priority date: 2003-11-14
Filing date: 2003-11-14
Publication date: 2006-06-21
Anticipated expiration: 2013-11-14

Abstract

The utility model discloses a three-coaxial cable and a using method thereof, which can be used in the high voltage substation with strong electromagnetic interference environment to serve as a transmission carrier for high frequency signals. As disclosed in the accompanying diagram 1, compared with the existing two-coaxial cable with the two ends of an external conductor contacting the earth, the differences of the utility model are that the utility model is added with an external shielding layer [5], and adopts continuous longitudinal coating art to form a metal tube shape external shielding body so as to form the three-coaxial cable. In application, the two ends of the external shielding body [5] contact the earth. One end of the external conductor which is the shielding layer contacts the earth directly, and the other end of the external conductor does not contact the earth or the other end of the external conductor contacts the earth through a capacitor. The disturbance current only can flow through the external shielding layer, which eliminates the disturbance of common impedance coupling, and the magnetic coupling disturbance is degraded further in reflection and energy absorption modes. The utility model adopts the good conductor and the magnetic conduction material to combine the shielding layer, which omits the earthed conductor which is parallel to the cable laying.

Description

Triaxial cable

1. technical field

The utility model relates to a kind of high-frequency signal transmission cable, the especially transmission cable of power-line carrier channel high-frequency signal and usage.

2. technical background

So far, the transmission cable of power-line carrier channel high-frequency signal is to adopt civilian common two coaxial cables always.This coaxial cable has only inside and outside two-layer conductor, and outer conductor promptly is jamming-proof screen, is again the return line of high-frequency signal.When it is installed on the abominable high voltage substation of electromagnetic environment as industrial products, by the needs of diamagnetic coupled interference, should be with its two-terminal-grounding.Under electrical network generation ground-fault condition, the big electric current of low frequency will produce for impedance coupling strong jamming high-frequency signal by outer conductor.This interference is blocked hf channel, even causes device damage.Cause circuit carrier current protection incorrect operation therefrom, the safe and stable operation of crisis electrical network and the reliability of power supply.For this reason, two coaxial cables have been taked " anti-accident measures ", promptly near cable laying 100mm ²The ground connection copper bar, add partiting dc capacitor, cable shield away from remedial measures such as primary equipment earth point ground connection.Though these measures can be played a role, can not deal with problems fully, by disturbing the accident that causes still to happen occasionally.

3. summary of the invention

Task of the present utility model provides a kind of triaxial cable, makes it to improve the fail safe of the high-frequency signal transmission under strong electromagnetic interference environment.For reaching this purpose, solution of the present utility model is to add one deck tubular outer shield layer again on the sheath of existing common two coaxial cables, constitutes triaxial cable.The outer shielding layer of triaxial cable is equivalent to the ground connection copper bar near cable, can play than common two coaxial cables and lay the ground connection copper bar, adds capacitance the better resisting interference effect is arranged.

In the use with the outer shielding layer two ends of coaxial cable metal shell ground connection through connected equipment, the direct ground connection of outer conductor one end, the other end is earth-free.Earth-current can only be flow through from outer shielding layer, be not loaded with the outer conductor of high-frequency signal, avoided the big electric current of low frequency that the common-impedance coupling that high-frequency signal produces is disturbed and do not flow through.On the other hand, vertically continuous tubular shielding body two-terminal-grounding can reduce the transfger impedance of coaxial cable, thereby can improve the anti-interference effect of reflection again, realizes further having suppressed the inductive coupled interference of high frequency magnetic field.Remedied existing coaxial cable disturbs powerless and diamagnetic coupled interference ability to the common-impedance coupling of low-frequency current generation shortcoming fully.

4. description of drawings

Below in conjunction with accompanying drawing the utility model is described in further detail:

Fig. 1: be the structural representation of triaxial cable.[1] among the figure, [3] are inner wire and outer conductor, are made of the soft copper conductor respectively; [2] be insulator in the polyethylene; [5] be the cast outer shielding layer that electric conducting material is done,, adopt wave structure for the flexibility and the screen cross section of cable; [4], [6] are polyethylene, polyvinyl chloride external insulation and oversheath.Wherein [5] should adopt good conductor to be overmolding to vertically continuous tubular shielding layer mainly as screen.

Fig. 2: be practical wiring schematic diagram.[7] are originally to be not less than 100 square millimeters of copper conductors along what cable louding laid among the figure; [8], [11] are the metal cabinet or the casings of coaxial cable two ends connecting device; [10] be the metal shell of coaxial cable two ends coupling arrangement.The outer shielding layer of coaxial cable [5] two ends are through the earthing of casing; Outer conductor [3] one end ground connection.

5. embodiment

Adopt the vertical job contract skill of rolling forging die to coat the tubulose outer shielding layer at the skin of common two coaxial cables.The seam of tubular outer shield layer is for flushing, and is not overlapping, to guarantee the requirement of concentricity.Adopt extrusion process to add the layer of polyethylene cable cover(ing) then on the outer shielding layer surface.Vertical bag of outer shielding layer and sheath extrusion molding can be finished on a production line.

When triaxial cable was used for power-line carrier channel and makes high frequency cable, its practical wiring was by shown in Figure 2.One end of inner and outer conductor [1], [3] and the output port of apparatus for transmitting signal join, and with [3] through the direct ground connection of the shell of transceiver (on during ground connection, ground connection) in addition as transceiver; The other end is connected the input port of road process equipment, direct ground network (can through capacitor grounding); The two ends of outer shielding layer [5] require to be connected to the metal cabinet or the casing of two ends connection device respectively with special connector, and accomplish reliably to link to each other with the bind earth mat.The earthing of casing downlead that note that outdoor passage process equipment not with the shared down conductor of down conductor of primary equipments such as capacitance type potential transformer.

Claims

1, a kind of high voltage substation of strong electromagnetic interference environment that is applicable to is made the triaxial cable of high-frequency signal transmission carrier, it is characterized in that: it has inner wire, outer conductor and 3 layers of conductor of outer shielding layer, and outer shielding layer adopts vertically continuous tubular shielding body.

2, triaxial cable according to claim 1 is characterized in that: outer shielding layer adopts sandwich construction, and each layer seaming position staggers, to improve the shielding benefit.

3, triaxial cable according to claim 1 is characterized in that: outer shielding layer adopts wrinkle structure, carvel joint, to increase flexibility and to guarantee concentricity.