I don't know if you have any knowledge about the requirements of the integrated wiring standard indicators. What are the requirements for the integrated wiring standard test indicators? Today, Xiaobian will discuss with you, and let's follow the editor to see it!
Integrated wiring standard test
First, the progress of integrated wiring standards
Some time ago, the twisted pair cables of integrated wiring copper cables on the market were mostly Category 3 and Category 5 twisted pair cables, and the optical cables used 62.5/125μm multimode optical cables. In recent years, the twisted pair cable has used Category 5e and Category 6 twisted pair cable. Optical cables have progressed from the latest published standards to 62.5/125μm and 50/125μm multimode optical cables used side by side. The computer network has progressed from 10Mbit/s, 100Mbit/s adaptive Ethernet network to 1000Mbit/s Ethernet network, which has new requirements for the integrated wiring transmission network.
The user determines which copper cable and optical cable to use in the project, and must carry out the project test of the integrated wiring to meet the index requirements, and then the project can be qualified for acceptance, otherwise it will not meet the standard requirements, which will affect the use. According to the communication industry standard of the People's Republic of China YD/T1013-1999 "General Test Method for Electrical Characteristics of Integrated Wiring System" and the 2000 Chinese version of Building Intelligence Industry Information "Foreign Standard for Integrated Cabling System", the latest standard test index requirements for integrated wiring are listed.
Two, twisted pair horizontal wiring link test parameters and technical indicators
1. Wiring diagram
In the preliminary work of the test, the connection diagram of the test shows the actual state of the connection of the 8 wires of each cable to the connection port. The correct wire pairs are: 1/2, 3/6, 4/5, 7/8.
2. Cable link length
The physical length of a wired cable link is derived from the measured round-trip propagation delay T of the signal over the link. In order to ensure the accuracy of length measurement, the NVP value (rated transmission speed) of the cable under test should be checked before this test. NVP=(speed of signal propagation in cable/speed of light)×100%, this value varies with different cable types. Typically, NVP ranges from 60% to 90%.
3. Characteristic impedance
Characteristic impedance refers to the resistance presented by the link over the specified operating frequency range.
The cable used for integrated wiring is 100Ω, no matter whether it is Category 3, Category 4, Category 5, Category 5e or Category 6 cable, the characteristic impedance of each pair of core wires should be constant and uniform throughout the entire working bandwidth range. Impedance discontinuities at any point on the link will cause signal reflections and signal distortions for that link. The difference between the characteristic impedance of the link and the standard value is less than or equal to 20Ω.
4. DC loop resistance
No matter Category 3, Category 4, Category 5, Category 5e or Category 6 broadband cable, in basic link mode, permanent link mode or channel link mode, the DC loop resistance of each wire pair of the cable is 20 The maximum value in the environment from degrees Celsius to 30 degrees Celsius: Category 3 links do not exceed 170Ω, and links above Category 3 do not exceed 30Ω.
5. Attenuation
Due to factors such as skin effect, insulation loss, impedance mismatch, connection resistance, etc., the energy of signal transmission loss along the link is called attenuation, which is expressed as the transmission loss value of the test transmission signal between the two ends of each pair and the same cable The difference between the attenuation of the worst of all pairs in the set relative to the maximum attenuation allowed. For a cabling link, the attenuation consists of the following components.
(1) The attenuation of each connector to the signal;
(2) The attenuation of the 10m jumper that constitutes the channel link mode or the 4m equipment wiring that constitutes the basic link mode to the signal;
(3) The attenuation of the signal by the wiring cable.
The maximum allowable attenuation value of each link for different types of cables at different frequencies and different link modes.
During the actual test, according to the site temperature, for the link formed by Category 3 cables and connectors, the attenuation increases by 1.5% for every 1 degree Celsius increase. For the link composed of Category 4 and Category 5 cables and connectors, the attenuation changes by 0.4% when the temperature changes by 1 degree Celsius. When the cable moves closer to the metal surface, the attenuation increases by 3%, and the correction above Category 5 can be determined.
6. Near-end crosstalk loss (NEXT) In a link, the signal coupling caused by electromagnetic induction of a certain transmitting line pair on one side of the cable to other adjacent (receiving) line pairs on the same side, that is, near-end crosstalk. The difference (dB) between the near-end crosstalk value (dB) and the transmitted signal (the reference value is set as 0dB) that causes the crosstalk is defined as the near-end crosstalk loss. The larger the NEXT value, the greater the NEXT loss. Near-end crosstalk is related to cable type, connection method, and frequency value.
7. Far-end near-end crosstalk loss (RNEXT)
Corresponding to the near-end crosstalk loss, at the other end of a link, the crosstalk caused by the electromagnetic induction coupling between the pair of transmitting signals and other adjacent (receiving) pairs on the same side is defined as the far-end near-end crosstalk loss. See Table 3 for the list of minimum near-end crosstalk losses for the technical specifications of the far-near-end crosstalk loss value. For a link, NEXT and RNEXT may be completely different values, and tests need to be carried out separately.
8. Adjacent pair combined near-end crosstalk (PSNEXT)
On one side of a 4-pair twisted pair, the sum of the crosstalk generated by the 3 transmitting signal pairs to the other adjacent receiving pair is approximately:
Among them, N1, N2, and N3 are the near-end crosstalk values of line pair 1, line pair 2, and line pair 3, respectively.
9. Near-end crosstalk and attenuation difference (ACR)
The definition of crosstalk attenuation is: the difference (unit is dB) between the crosstalk loss (NEXT) and the transmission signal attenuation value (A) of the current pair on the pair that is crosstalked by the adjacent sending pair, that is, ACR (dB) =NEXT(dB)-A(dB) For the link formed by Category 5 and higher cables and similar connectors, due to high frequency effects and various interference factors, the standard parameters of ACR are not simply crosstalk loss from Table 3 The direct algebraic difference between the value NEXT and the attenuation value A in Table 2 at each corresponding frequency is derived, and the link ACR can usually be improved by increasing the link crosstalk loss NEXT or reducing the attenuation A level. The ACR requirement is positive at 200MHz for Category 6 cabling links, and Category 6 cabling links are required to measure up to 250MHz.
Note: This table is given with reference to the classD link in 6.2.5 of the ISO11801-1995 standard
10. Equivalent Far End Crosstalk Loss (ELFEXT)
It refers to the difference between far-end crosstalk loss and line transmission attenuation. A signal is sent from a pair of cables at the near end of the link. The signal is attenuated by the line and interferes with the adjacent receiving pair from the far end of the link. The far-end crosstalk value is defined as FEXT. FEXT is an amount that varies with link length (transmission attenuation).
Definition: ELFEXT=FEXT-A (A is the transmission attenuation of the crosstalk receiving pair)
11. Sum of far-end equivalent crosstalk (PSELFEXT)
The limit value of the equivalent crosstalk ELFEXT sum of the adjacent pairs of adjacent pairs on the disturbed receiving pair at the far end of the cable.
12. Propagation delay T
In channel connection mode, basic connection mode or permanent connection mode, when transmitting signals with frequencies of 10 to 30 MHz for Category 5 and below links, the transmission delay of any pair in the cable is required to be T≤1000ns; for Category 5e , Category 6 link requires T≤548ns.
13. Propagation delay difference between pairs
The delay value of the line pair with the smallest signal propagation delay in the same cable is used as a reference, and the delay difference between the remaining line pairs and the reference line pair shall not exceed 45ns. If the line-to-line delay difference exceeds this value, the data frame structure will be seriously damaged when four line pairs transmit data signals in parallel under the high-speed data transmission of the link.
14. Return Loss (RL) Return loss is caused by power reflections caused by cable characteristic impedance and link connectors deviating from standard values. RL is the difference between the amplitude of the input signal and the amplitude of the signal reflected back by the link, and Table 8 lists the standard value of return loss.
15. Link impulse noise level
This refers to the electrical shock interference on the wiring link caused by the intermittent startup of high-power equipment. The statistics of the number of impulse noises higher than 200mV occur in the wiring link without connecting active devices and equipment, and the number of impulse noises captured within 2 seconds of the test is not more than 10.
16. Background noise refers to high-frequency interference, electromagnetic interference and stray broadband low-amplitude interference caused by general electrical equipment. When the wiring link is not connected to active equipment and equipment, the noise level should be less than or equal to -30dB.
17. Safety inspection of integrated wiring grounding system
When the integrated wiring system adopts shielding measures, there must be a good grounding system, and it should meet the following requirements:
(1) The grounding resistance value of the protective ground wire should not be greater than 4Ω when the grounding body is set alone; when the combined grounding body is used, it should not be greater than 1Ω.
(2) When using a shielded wiring system, all shielding layers should maintain continuity.
(3) When using a shielded wiring system, the wiring equipment (FD or BD) end of the shielding layer must be well grounded, the user (terminal equipment) end should be grounded according to the specific situation, and the grounding at both ends should be connected to the same grounding body. If there are two different grounding bodies in the grounding system, the grounding potential difference should not be greater than 1Vrms.
(4) When the shielded wiring system is used, the wiring cabinets on each floor should be individually wired to the grounding body with copper wires of appropriate cross-section, or the centralized copper bars or thick copper wires in the shaft can be used to lead to the grounding body, and the wires or The cross-section of the conductor shall comply with the standard. The grounding wire should be connected to a tree-like grounding grid to avoid forming a DC loop.
(5) When the cables of the integrated wiring are laid with metal channels or steel pipes, the channels or steel pipes should maintain continuous electrical connection, and there should be good grounding at both ends.
(6) Measure the potential difference between the shielding layer of the shielded cable and the grounding layer of the shielded cable at both ends of the link and the grounding layer at both ends is ≤5V.
3. Optical cable transmission link
The main technical parameters of the multimode fiber used in the wiring in the building are: attenuation and bandwidth. The 62.5/125μm fiber operates in the 850μm, 1300μm dual wavelength window.
Satisfy the working bandwidth of 160MHz under 850μm;
Satisfy the working bandwidth of 550MHz under 1300μm;
Transmission attenuation is the most important technical parameter of optical fiber links under the guaranteed working bandwidth.
A light=αL=10~10(P1/P2)α: attenuation coefficient; L: fiber length P1: the optical signal generator injects optical power into the fiber at the beginning of the fiber link P2: the optical signal receiver receives of optical power
Optical fiber link attenuation calculation: A(total)=Lc+Ls+Lf+Lm
in:
Lc: connector attenuation; Ls: connector attenuation; Lf: fiber attenuation; Lm: margin.
When the fiber length in the building does not exceed 500m, A (total) should be: 850μm: A (total) ≤ 3.5dB 1300μm: A (total) ≤ 2.2dB
The above are the indicators of multimode fiber.
4. Single-mode fiber optic cable
Attenuation at 1310μm≤0.3～0.4dB/km; transmission gigabit network attenuation <4.7dB/km.
Fiber optic cables can be tested using the FLOKEDSP/4000 instrument. Multimode optical cable uses FTK accessories and LED light source to measure two wavelengths of 850nm and 1300nm. Single-mode fiber uses LS accessories and laser light source to measure two wavelengths from 1310nm to 1550nm.
The above is all the content of the requirements of the integrated wiring standard test indicators. I hope this article can give you some help! More exciting things are waiting for you in Qianjiawang!
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