CN1412785A - SFTP extra five metal braided shielded cable - Google Patents

Abstract

The present invention relates to network communication products, in particular to a SFTP category five metal braided shielded cable improved on the basis of UTP and FTP cables. For the four pairs of wire cores, an aluminum-plastic composite tape shielding layer is provided in the sheath layer to cover the wire cores, and it is characterized in that, between the sheath layer and the aluminum-plastic composite tape shielding layer A metal wire braided shielding layer is also provided, and a metal wire for grounding extending along the network cable is provided between the aluminum-plastic composite tape shielding layer and the metal wire braided shielding layer. This kind of cable has the electrical performance of super-category five cables. It not only has an aluminum-plastic composite tape shielding layer, but also has a layer of metal braided shielding layer with a density of 92%, which greatly improves the shielding effect of the cable.

Description

SFTP super five-class metal braided shielded cable

Technical Field

The invention relates to a network communication product, in particular to an SFTP (Small form-factor pluggable) super-five metal braided shielding cable with strong anti-electromagnetic interference capability, which can be applied to the fields of multimedia, data communication and the like.

Background

In the signal transmission with higher speed, the mutual crosstalk and the external interference between the cable loops can influence the transmission quality to generate signal distortion and distortion, the principle of cable shielding is to utilize a metal shielding body to weaken the electromagnetic field of an interference cable, and the cable shielding has three types:

1. electrostatic shielding: its function is to terminate the electric field on the metallic surface of the shield (shield layer) and to transfer the charge to ground through grounding means.

2. Magnetostatic shielding: the function of which is to confine the magnetic field inside the shield, which is usually a ferromagnetic material such as steel.

3. Electromagnetic shielding: the shielding mode is adopted by the shielding net wire, and the shielding effect is realized by utilizing the reflection of the shielding body and the attenuation of high-frequency energy in the shielding body at high frequency. For example, the wave impedance of the shielding layer is different from the wave impedance of the surrounding medium, which causes electromagnetic wave reflection and loss caused by eddy current in the metal material, thereby achieving the purpose of shielding.

With the advancement of technology and the rapid development of information technology, the communication trunk is gradually replaced by the optical cable, but the signal transmission of the last kilometer still needs to be completed by using the twisted pair cable, the applications of the five types of cables in the last kilometer are more and more extensive, and the transmission performance requirement of the five types of cables is also continuously increasing, the UTP five type cable (referred to as UTP CAT5 for short) is one of the widely used network cables, and the structure of the cable is shown in fig. 1.

As can be seen from fig. 1, the UTP CAT5 cable 1 includes cores 12, insulation 18 respectively covering each core 12, a polyester tape layer 16 for ensuring cable roundness, and an outermost sheath layer 11 having a tear line 17 on its inner surface for facilitating tearing of the sheath layer 11. The conductor of the wire core 12 is a single tinned copper wire conductor or a multi-strand tinned copper wire stranded conductor of 24AWG generally; the insulating material 18 is polyethylene plastic with a better dielectric coefficient; the sheath layer 11 is made of polyvinyl chloride sheath material with better flame retardant property by drawing. The UTP CAT5 cable has the advantages of special processing technology compared with the common symmetrical cable, high precision of the diameter of the conductor and the outer diameter of the insulation, good uniformity, the precision of the outer diameter of the insulation is below 0.03mm, the precision of the diameter of the conductor is below 0.001mm, the higher the precision of the outer diameter is, and the better the uniformity of the impedance is. The UTP CAT5 cable 1 is formed by twisting 4 pairs of wire pairs with different pitches, and then a layer of flame-retardant polyvinyl chloride is extruded to be used as a sheath layer 11, so that a finished cable is obtained, and the polyvinyl chloride with different grades is selected, so that the cable can meet the requirements of different flame-retardant grades.

The general structural parameters of UTP CAT5 cable are as follows:

(1) conductor direct current resistance: less than or equal to 93.8 omega/100 m;

(2) insulation resistance: not less than 5000M omega.km;

(3) capacitance imbalance between line pairs: less than or equal to 330pF/100 m;

(4) resistance imbalance: is less than 5 percent.

The electrical performance parameters of UTP CAT5 cable (single conductor) such as characteristic impedance, return loss, attenuation, near-end crosstalk power and equivalent operating crosstalk are shown in table one:

watch 1

Frequency MHz	Characteristic impedance ohm	Return loss dB	Attenuation dB/100m	Near-end crosstalk dB	Near-end crosstalk power sum dB	Equivalent far-end crosstalk dB
							0.772	100±15	16.7	1.8	64.0	64.0	63.0
1.0	17.0	2.0	62.3	62.3	60.8
						4.0	18.8		4.1	53.3	53.3	48.7
8.0	19.7	5.8	48.8	48.8	42.7
						10.0	20.0		6.5	47.3	47.3	40.8
16.0	20.0	8.2	44.3	44.3	36.7
						20.0	20.0		9.3	42.8	42.8	34.7
25.0	19.3	10.4	41.3	41.3	32.8
						31.25	18.6		11.7	39.9	39.9	30.9
62.5	16.5	17.0	35.4	35.4	24.8
						100	15.1		22.0	32.3	32.3	20.8

In early lan networks, category 5 cables in UTP architecture were often selected for the network cabling. The UTP cable has no shielding protection measure, electromagnetic interference energy is generated in the process of transmitting signals on the cable and can be transmitted outwards through the space, and the cable does not have the capacity of resisting external electromagnetic interference and cannot prevent the interference of an electromagnetic field of the external space. The UTP cable has no shielding layer, and can only balance and filter the interference through a medium, a filter and a balance-unbalance converter so as to achieve the purpose of preventing the interference; in addition, the adaptive connector used with the UTP5 cable is also a non-shielded model socket and a non-shielded model plug, so the UTP cable cannot achieve the shielding effectiveness of the cable, and cannot meet the requirement of product design in terms of EMC.

In order to internationalize products and meet the requirements of product design EMC, cables in the form of FTP structures are produced. The FTP CAT5 cable structure is shown in fig. 2, and it can be seen from fig. 2 that the FTP cable 2 comprises a single-sided aluminum-plastic composite tape layer 23 between the polyester tape layer 26 and the sheath layer 21, in addition to the core 22 surrounded by the insulation material 28, the polyester tape layer 26 for ensuring the cable roundness, and the outermost sheath layer 21, the aluminum-plastic composite tape layer 23 has an inward side of aluminum foil and an outward side of PE plastic. Namely, a layer of wrapped aluminum foil 23 is added in the structure of the UTP five-type cable, and a grounding wire 24 is arranged on the aluminum foil surface of the aluminum-plastic composite tape 23 to facilitate shielding and grounding. As with the UTP cable, a tear line 27 is provided on the inner surface thereof to facilitate tearing of the sheath layer 21.

Compared with the FTP CAT5 cable and the UTP CAT5 cable, the FTP CAT5 is structurally provided with a layer of aluminum foil 23 and a grounding conductor 24, and the grounding conductor can enable the shielding of the cable to be grounded easily. FTP CAT5 cable and UTP CAT5 cable have substantially identical performance requirements in electrical performance. The difference is that FTP CAT5 cable increases shielding effectiveness over UTP CAT 5. UTP CAT5 cable itself is free of any shielding protection, while FTP CAT5 achieves a considerable degree of shielding effectiveness.

It can be seen that the shielding of the FTP cable is realized by a layer of aluminum foil 23 and a grounding wire 24, the effect and the range of electromagnetic interference shielding are small, the thickness of the aluminum foil is limited, the conduction of electromagnetic radiation can not be effectively prevented in a high-frequency electromagnetic field, and the capacity of reflecting the electromagnetic energy in the space is small; and when the cable is bent in use, the aluminum foil is easy to damage due to the fragility, so that the cable cannot play a shielding role. The EMC test is to investigate the overall shielding effectiveness, and partial loss of the shielding function is equivalent to deterioration of the overall shielding function.

With the development of information technology, a great number of high-frequency transmission modes are adopted between the inside of the communication equipment and the communication equipment, and meanwhile, a great number of stronger electromagnetic interferences are derived to cause distortion of signal, image and data transmission, so that the aluminum foil shielded cable FTP is increasingly disfavored in the aspect of electromagnetic interference prevention. Therefore, it is required to design a cable having a better shielding performance on the cable connection of the device.

Disclosure of Invention

The technical problem to be solved by the invention is to provide an SFTP extra-five metal braided shielded cable (SFTP CAT5e) aiming at the above defects of the existing UTP CAT5 cable and FTP CAT5 cable in the shielding aspect, which has better shielding effect and the electrical performance of the extra-five cable.

The technical scheme of the invention is that the SFTP super five-class metal braided shielded cable is characterized in that a metal wire braided shielding layer is arranged between the sheath layer and the aluminum-plastic composite tape shielding layer, and a metal wire which extends along the network wire and is used for grounding is arranged between the aluminum-plastic composite tape shielding layer and the metal wire braided shielding layer.

In the cable, the overlapping rate of the shielding layers of the aluminum-plastic composite belt is more than 30 percent; the plastic-aluminum composite tape shielding layer is also internally provided with a polyester tape which wraps the wire core, so that the roundness of the wire core of the cable can be improved.

In the cable, the metal wire braided shielding layer is a tinned copper wire braided shielding layer, and the braiding density of the metal wire braided shielding layer is 92%; the specification of the tinned copper wire braided shielding layer is 16 multiplied by 8 multiplied by 0.16, which means that 16 copper wires are braided in the shielding layer, each copper wire has 8 copper wires, and the outer diameter of each copper wire is 0.16 mm.

In the cable of the present invention, the metal wire for grounding is a tinned copper wire of 24 AWG.

In the cable of the invention, the insulating material is foamed PE with low dielectric loss coefficient, the insulating outer diameter is 1.00 +/-0.03 mm, and the insulating resistance is more than 10000 MOmega-km.

In the cable, the core conductor is a single 24AWG tinned copper conductor, the diameter of the core conductor is 0.525 +/-0.005 mm, and the direct-current resistance of the core conductor is less than 9.38 omega/100 m. The conductor with the wire core has the advantages of good tensile strength, good elongation at break and good diameter stability.

In the cable, the pitch of the four pairs of wire cores is 12-21 mm, and the color spectrums of the twisted pair wires are respectively blue-white blue, orange-white orange, green-white green and brown-white brown.

In the cable, the sheath layer is made of flame-retardant polyvinyl chloride (PVC), the average thickness of the sheath layer is 0.57mm, the thinnest thickness of the sheath layer is 0.52mm, and the outer diameter of the sheath layer is 6.8 +/-0.2 mm.

It can be seen that the SFTP super five-class metal braided shielded cable (SFTP CAT5e) provided by the invention not only has an aluminum-plastic composite tape shielding layer, but also has a metal braided shielding layer with the density of 92%, so that the shielding effect of the cable is greatly improved. In addition, the cable has the electrical performance of a super-five-type cable.

The invention will be further explained with reference to the drawings and the embodiments.

Drawings

Fig. 1 is a schematic cross-sectional structure of an UTP cable;

FIG. 2 is a schematic cross-sectional structure of an FTP cable;

FIG. 3 is a schematic cross-sectional view of SFTP CAT5e in accordance with the present invention;

FIG. 4 is a schematic representation of SFTP CAT5e with portions of the jacket peeled away.

Detailed Description

Although SFTP cables have been proposed in the industry for many years, no metal braided shield is used in the country on the category of extra-five cables, and no precedent is found in applying SFTP CAT5e to products. The invention provides parameters such as complete SFTP CAT5e electrical performance, structural size and the like according to the design requirement of a product and the characteristics of a shielding network cable processing technology. In electrical performance, the transmission characteristics of the cable are mainly determined according to EIA/TIA 568A (commercial building integrated wiring standard) and EIA/TIA 568A-5 (4-100 omega enhanced category 5 cable); in terms of structure size, proper cable structure parameters are selected mainly according to the structure characteristics of the original UTP CAT5 and FTP CAT5 so as to meet the electrical performance requirements of the ultra-five cable. The physical and mechanical properties of the SFTP CAT5e are required to meet the requirements of relevant national standards or the standards of the post and telecommunications industry, and the flame retardant performance of the cable can pass the relevant flame retardant grade of the NEC standard and the safety certification of the test and UL relevant grade.

The SFTP CAT5e is constructed as shown in fig. 3 and 4, and the cable 3 has four pairs of cores 32, each pair being surrounded by insulation 38; then, a layer of polyester tape 36 is wrapped around the four pairs of wire cores 32 to completely wrap the four pairs of wire cores, so that the roundness of the cable core can be improved; and the aluminum-plastic composite tape shielding layer 33 and the copper wire braided shielding layer 35 are adopted for double-layer shielding, so that the shielding effect is better than that of the original single-layer aluminum foil shielding cable FTP, the shielding coverage rate of the wires exceeds 90 percent, a copper conductor grounding wire 34 is arranged between the aluminum-plastic composite tape shielding layer 33 and the copper wire braided shielding layer 35, and the good continuous conductor can ensure the continuity of grounding. Meanwhile, there is a tear line 37 in the sheath layer 31. The SFTP CAT5e cable is formed by adding a layer of copper wire braided shield 35 on the basis of the original FTP CAT5 cable structure. The cable not only has the electrical performance of the super-five types of cables, but also meets the requirements of EMC (electro magnetic compatibility), on one hand, copper in the copper wire braided shielding layer 35 has good conductivity, and can quickly leak electromagnetic interference energy to the ground in a grounding mode, and on the other hand, the copper wire braided shielding layer 35 isolates the cable from external signals around a cable core, like a barrier, and prevents electromagnetic interference energy radiation.

The main features of the SFTP CAT5e cable will be described in detail below:

a conductor

In SFTP CAT5e, the conductor in the wire core 32 adopts a 24AWG single tin-plated copper conductor, and has better tensile strength, elongation at break and diameter stability. Wherein,

diameter of the conductor: 0.525 +/-0.005 mm;

direct current resistance: less than or equal to 9.38 omega/100 m.

Second, the core insulation

In SFTP CAT5e, the insulating material 38 outside the wire core 32 is made of foamed pe (foam pe) with a low dielectric loss coefficient, and the insulating material 33 has good stability of the outer diameter of the insulation, proper elongation at break and insulation stripping degree. Wherein,

insulating outer diameter: 1.00 +/-0.03 m;

insulation resistance: more than 10000M omega km.

Triple, double twist pitch

In SFTP CAT5e, the pitches of four groups of twisted pairs of a wire core 32 are controlled between 12mm and 21mm, and the chromatograms of the twisted pairs are respectively as follows: blue-white blue, orange-white orange, green-white green, brown-white brown.

Four, cabling

In SFTP CAT5e, the total cabling pitch of four pairs of twisted wires of a wire core 32 is about 300 mm-400 mm, the four pairs of core wires with different chromatograms are cabled according to a certain set pitch, then a polyester tape 36 is wrapped, a plastic-aluminum composite tape 33 is wrapped, finally a layer of tinned copper wire 35 is woven, the specification of the woven copper wire is 16 x 8 x 0.16, which indicates that the woven copper wire has 16 ingots, each ingot has 8 copper wires, the outer diameter of each copper wire is 0.16mm, and a tinned copper wire 34 of 24AWG for grounding is added between the plastic-aluminum composite tape 33 and the copper wire braided layer 35. Wherein, the overlapping rate of the aluminum-plastic composite belt 33 is required to be more than 30%, and the density of the copper wire braided layer 35 is required to be 92%.

Five, sheath layer

In SFTP CAT5E, the material of the sheath layer 31 is flame-retardant PVC, the average thickness is 0.57mm, the thinnest is 0.52mm, the outer diameter of the sheath is 6.8 +/-0.2 mm, and the color of the cable sheath is gray (refer to a standard color plate: PANION 445U, the color difference Delta E is less than or equal to 1.00). The lettering of the sheath of the cable includes, but is not limited to, the following: UL CM 4PR 24AWG SFTP CAT5e 75 ℃.

Sixth, safety

According to UL1581 standard, SFTP CAT5e cable passes vertical burning test and reaches CM flame retardant grade of NEC standard.

Seventh, the electrical properties of SFTP CAT5e are shown in Table two

Watch two

Frequency MHz	Characteristic impedance ohm	Return loss dB	Attenuation dB/100m	Near-end crosstalk string dB	Near-end crosstalk power sum dB	Equivalent far-end crosstalk dB	Equivalent crosstalk power sum dB
								0.772	100±15	19.4	1.8	67.0	64.0	66.0	63.0
1.0	20.0	2.0	65.3	62.3	63.8	60.8
							4.0	23.0		4.1	56.3	53.3	51.7	48.7
8.0	24.5	5.8	51.8	48.8	45.7	42.7
							10.0	25.0		6.5	50.3	47.3	43.8	40.8
16.0	25.0	8.2	47.3	44.3	39.7	36.7
							20.0	25.0		9.3	45.8	42.8	37.7	34.7
25.0	24.3	10.4	44.3	41.3	35.8	32.8
							31.25	23.6		11.7	42.9	39.9	33.8	30.9
62.5	21.5	17.0	38.4	35.4	27.8	24.8
							100	20.1		22.0	35.3	32.3	23.8	20.8

Compared with the electrical performance (table one) of the five-type UTP cable, the electrical performance (table one) of SFTP CAT5e has the performance indexes of return loss, near-end crosstalk power sum, equivalent far-end crosstalk power sum and the like of the cable under the same condition.

Eight, main applications

Table three shows the differences in the application of the seed cables:

watch III

Kind of cable	Transmission Bandwidth (MHz)	Transmission Rate (Mbps)	The main application
				UTP CAT5	100	100	Fast Ethernet
FTP CAT5	100	100	Fast Ethernet
				SFTP CAT5e	100	155	Gigabit Ethernet

By comparing the various performances of the three cables UTP, FTP and SFTP CAT5e, it can be seen that:

for FTP cable, the shielding efficiency is low because only one layer of aluminum foil total shielding is provided, but the SFTP CAT5e cable not only has the aluminum foil total shielding, but also has a metal braided shielding layer with the density of more than 90 percent, and the shielding efficiency of the cable can be greatly improved.

As the most core technology of the invention, the SFTP CAT5e is obtained by improving the original UTP CAT5, namely the copper wire braided shield is added in the structure of the five-class cable, the braiding density is positioned at 92 percent in the invention, and the cable reaches the electrical performance index of the super five-class cable through the control process of a cable production workshop. The shielding effects of the FTP cable and the SFTP cable with the metal wire braided shielding density of 92% are tested and compared, and the table shows the shielding efficiency test results of the FTP cable with the length of 100m and the SFTP cable within the range of 30MHz to 250MHz and four pairs of twisted pairs at 8 frequency points respectively; as can be seen from table four, the average value of the shielding effectiveness of the FTP cable is 43.5 dB; the average value of the shielding effectiveness of the SFTP cable with the metal wire braided shielding density of 92 percent can reach 81 dB. Therefore, the metal wire braided shield SFTP cable has better EMC performance than the FTP cable.

Watch four

Test Item	Unit	Test results Test Result
				Coupling loss		1#FTP	2# SFTP (90% braided shield)
30MHz	dB	Orange-white orange: 47.2 white-white brown: 42.1 Green-white Green: 48.6 blue-white blue: 52.6	Orange-white orange: 72.1 Brown-white Brown: 74.0 Green-white Green: 72.9 blue-white blue: 73.2
				62.5MHz	dB	Orange-white orange: 41.3 Brown-white Brown: 43.3 Green-white Green: 42.2 blue-white blue: 48.4	Orange-white orange: 84.6 brown-white brown: 80.7 Green-white Green: 84.9 blue-white blue: 84.4
90MHz	dB	orange-white orange: 36.9 brown-white brown: 51.3 Green-white Green: 35.9 blue-white blue: 45.4	Orange-white orange: 84.2 brown-white brown: 80.3 Green-white Green: 83.3 blue-white blue: 79.6
				100MHz	dB	Orange-white orange: 38.6 brown-white brown: 36.2 Green-white Green: 34.0 blue-white blue: 44.6	Orange-white orange: 94.8 brown-white brown: 87.5 Green-white Green: 83.4 blue-white blue: 85.9
125MHz	dB	Orange-white orange: 42.0 brown-white brown: 39.8 Green-white Green: 37.6 blue-white blue: 43.6	Orange-white orange: 87.3 Brown-white Brown: 84.3 Green-white Green: 76.6 blue-white blue: 78.7
				150MHz	dB	Orange-white orange: 40.5 brown-white brown: 41.2 Green-white Green: 40.7 blue-white blue: 52.5	Orange-white orange: 74.5 brown-white brown: 79.3 Green-white Green: 75.7 blue-white blue: 78.3
200MHz	dB	Orange-white orange: 50.7 brown-white brown:45.4 Green-white Green: 43.4 blue-white blue: 47.5	Orange-white orange: 80.5 Brown-white Brown: 83.8 Green-white Green: 77.2 blue-white blue: 82.8
				250MHz	dB	Orange-white orange: 38.6 brown-white brown: 46.0 Green-white Green: 49.2 blue-white blue: 49.5	Orange-white orange: 82.1 brown-white brown: 80.1 Green-white Green: 83.4 blue-white blue: 82.6

Claims (10)

1. An SFTP category five metal braided shielded cable, the outermost layer is a sheath layer, and the innermost layer is four pairs of wire cores wrapped by insulating materials, and an aluminum-plastic composite layer is arranged in the sheath layer. A shielding layer encloses the wire core, and it is characterized in that a metal wire braided shielding layer is also provided between the sheath layer and the aluminum-plastic composite tape shielding layer, and between the aluminum-plastic composite tape shielding layer and the A metal wire for grounding extending along the network cable is also provided between the wire braided shielding layers. 2. The cable according to claim 1, characterized in that, a polyester tape wrapping around the wire core is further arranged in the shielding layer of the aluminum-plastic composite tape. 3. The cable according to claim 1, characterized in that the metal wire braided shielding layer is a tinned copper wire braided shielding layer, and the braiding density of the tinned copper wire braided shielding layer is 92%. 4. The cable according to claim 3, characterized in that the specification of the tinned copper wire braided shielding layer is 16×8×0.16, wherein there are 16 braided copper wires, and each ingot has 8 copper wires, The outer diameter of each copper wire is 0.16mm. 5. The cable according to claim 1, wherein the metal wire for grounding is 24AWG tinned copper wire. 6. The cable according to claim 1, wherein the insulating material is foamed PE with a low dielectric loss coefficient, the outer diameter of the insulation is 1.00±0.03mm, and the insulation resistance is greater than 10000MΩ·km. 7. The cable according to claim 1, wherein the core conductor is a 24AWG single tinned copper conductor with a diameter of 0.525±0.005mm and a DC resistance of less than 9.38Ω/100m. 8. The cable according to claim 1, wherein the pitch of the four pairs of wire cores is between 12 mm and 21 mm, and the color spectrum of the twisted pair wires is blue-white-blue, orange-white-orange, green-white-orange, respectively. White-green, brown-white-brown. 9. The cable according to claim 1, characterized in that, the sheath layer is flame-retardant polyvinyl chloride, its average thickness is 0.57 mm, the thinnest thickness is 0.52 mm, and the outer diameter of the sheath layer is 6.8 ±0.2mm. 10. The cable according to claim 1, characterized in that the overlapping ratio of the shielding layer of the aluminum-plastic composite tape is greater than 30%.