【 Weak current college 】 computer cable cost accounting methods

Cable design and material consumption calculation cable structure design is to wire the components of the arguments written in the design process, notably the relevant standards according to the wire, combined with our production capacity, to meet customer requirements, and the results expressed in writing, provide a basis for production of materials usage calculation is-according to the design of the material when the selection of wire rod and structure parameters, calculate the amount of materials, cost for accounting and warehousing, material basis. part of the conductor design and computing: conductor in structurally solid and stranded wire two, while its composition has a pure metal-alloy plating and enameled wire, etc.. in the design process, for different wire use these conductors, based on the following aspects:
1. the wire after using the site and order processing mode.
2. the conductor material properties: conductivity, heat resistance-tensile strength. processing. elasticity, etc.
1. conductor stranded pitch design: strand stranded pitch size in General according to stranded conductor wire gauge select (mainly for UL e line series, power cord, UL444 series, CSATR-4 series on conductor pitch is required, need based on standard design), sometimes in order to improve the performance of a certain other optional as communication wire pitch-to-use small pitch decay, in order to provide good bending performance selection smaller pitch .2. multiple root stranded conductor stranded outside diameter calculation: conductor stranded with bunch of twisted way, stranded outside diameter using the following two methods of calculation:
Method 1: method 2: d--single conductor diameter D---stranded conductor stranded after N-od--conductor elements of these two methods,
Method 2 is suitable for beam stranded conductor stranded outside diameter calculation methods:
3. the amount of computation: conductor
1. single conductor
2. stranded conductor d----single conductor diameter and density ρ-conductor N-conductor stranded cable λ-conductor stranded in the calculation of the coefficient Note: dosage to single-dose, when the conductor when more cores to be taken into account when stranded wire stranded in coefficients.
4. conductor anti-oxidation. to prevent oxidation of the conductor, the conductor stranded, combined with the BAT or DOP oil (such as power cables, transparent line). Extrusion parts of the design and calculation: extruder section includes insulation extruder was out of the inner and outer was out, custody out process, due to different requirements on the wire using a charge out of the way different. normally, insulated with extrusion-extruder, sheath with protective coverings used half a squeeze tube-sometimes in order to meet the performance requirements using squeeze tube-specific Select method, the reference to the extruder technology.
1. charge the material of choice: the design process in the material of choice for the main purpose of under rubber compound, temperature levels, luster, soft degrees, plasticizer resistant to migration, non-toxic properties, to select.
2. the charge out outside diameter: D2 = D + 2 * TD------extruder diameter D2 before----charge out outside diameter T------extruder thickness extruder thickness (T) primarily on the basis of relevant criteria, combined with wire plant equipment production capacity to meet customer requirements.
3. compound fertilizer: extruding using different modalities, extruding compound dosage calculation formulas differ. squeeze tube extrusion-W = (S products section-S cable core contents) * ρ ρ-sizing material density. considering the wire tolerance, current cable companies generally use the following calculation method .W = 3, 14159 * 1.05 * T * (2 * D + T) * ρ core wire stranded on the design and calculation of: core wire stranded internally called the cabling that is most multi-core cable production of one of the important processes. The number of the insulated conductors or cell groups stranding core process called core wire stranded. The principle is similar as conductor stranded, core wire stranded General technical parameters calculation and core in stranded during deformation and strand. Core wire stranded as stranded insulated conductors diameter is the same as divided into symmetric stranded and asymmetric stranded. Because the core wire in stranded in the process of bending deformation, some thicker insulated cores in stranded procedure takes retreat-spiralling. If UL2919, CAT.5, IEEE1394, DVI cores and other high foam insulated cores.
The following points describe several aspects of the core wire stranded process parameters calculation:
1. twisted pair: the strand of equivalent diameter: D = 1.65d or 1.71d (soft use 1.65d, hard to use 1.71d), sometimesD = 1.86d complex on strand equivalent diameter: D = 2.6d multiple logarithmic strand equivalent diameter: twisted pair pitch according to twist the logarithm, core wire outer diameter selection.
2. multi-core stranded: stranded outside diameter when not many core elements, the calculation by the formal stranded-see form. arrangement and core wire core wire stranded outside diameter calculation according to the following table: when more cores number and diameter of smaller cases, you can beam stranded approximate calculation (conductor stranded outside diameter calculation formula) stranded pitch General stranded pitch get stranded outside diameter of 15-20 times-sometimes in order to improve performance, you can choose wire suitable pitch. If in order to improve the performance of bended wires twisted pitch .USB cable in order to reduce the core wire deformation, big pitch.

3. stranded in the base circle diameter. the pitch diameter. stranded outside diameter
Base diameter: for a stranded wire, stranded wire diameter said before the base circle diameter.
Pitch circle diameter: single-stranded in a cylinder of a diameter D0 to single line on axes to strand axis distance of RADIUS circle to its diameter, pitch to pitch circle diameter.
Stranded outside diameter: layer strand of the external diameter of the cable external diameter.
The figure for the third layer stranded: base circle diameter D0 (that is, the second layer (1 + 6) stranded in stranded outside diameter)
Pitch circle diameter is D ' D ' = D0 + d
The twists of the outer diameter is D ' + DD = d
4. stranded in the coefficient:
Core wire stranded in stranded in the coefficient is 1 + (PI X stranded outside diameter/stranded pitch) of the second party.
D-stranded outside diameter.
H-----stranded pitch.
In the strand, for multiple-core and core layer, although as a bunch of twisted, each core wire strand into the coefficients are not the same, in order to increase safety for the sake of conservativeCoefficient, and reduced calculation, so in the above stranded in the coefficients of the adoption of core wire stranded in D's stranded outside diameter (in theory, the layer of stranded coefficient should be a section on the circle diameter substitution-calculation).
Oblique package for the design and calculation of
Cross package in wire shielding effect of the main play, sometimes as coax's outer conductor.
Shield is designed to eliminate the external dry Flex, for coaxial cables, because of the impedance of the shield to match, reduce signal or transmission loss of energy.
From shielding effect, rather than stay package, its braided shielding effect directional, bending shielding characteristics change but its complete outer diameter is small, wire soft, the price is relatively low. Suitable for low-frequency shielding. The following narrative from several aspects of helical structure design of the package:
1. number of copper ramp package approximate calculations:
Integer part of the
D-inclined package before outer diameter.
D------diameter of oblique packagecopper wire.
If this is the second, three-wire stranded, stranded after not rounded, D (oblique package) outer diameter is equivalent diameter.
The design of the front outer diameter D oblique package, corresponding strand base diameter. Speaking from the theoretical calculations, to achieve 100% cross package D pitch diameter should be used, but in order to prevent sometimes because of pitch selection less, and other factors had a full (easy unit). D use of oblique package front outer diameter (base diameter). In actual production, because of the oblique package copper wire typically 0.10mm, 0.12mm fine lines, its value in the above calculation ignores. Use the above formula, the oblique package full of up to 90% or more, the performance impact on the wire.
2. the choice of stay package pitch:
Oblique package pitch diameter under diagonal size choice before the package, typically the following tuning pitch selection (this tuning pitch the cost, adhesion, appearance, etc., and through the long production verification).
The finished diameter oblique package pitch
d<1.0mm
About 15.5mm
1.0<=d<1.2mm
About 18mm
1.2<=d<2.0mm
About 22mm
2.0<=d<2.2mm
About 25mm
2.2<=d<2.4mm
About 27mm
2.4<=d<3.0mm
About 32mm
3.0<=d<3.5mm
About 36mm
3. stranded in the coefficient:
Oblique package twisted into the coefficient is 1 + (PI X diameter/after the oblique package inclined package pitch) of the second party.
D-inclined Pack outer diameter.
H-inclined package pitch.
4. the amount of skew package copper wire:
D-helical bundle conductor diameter
Ρ-helical bundle conductor density
N-inclined package conductor elements
Λ-inclined package conductor stranded in coefficients
5. Select oblique orientation package.
Oblique package generally use and cabling of the opposite direction: oblique package wire production process, and oblique inclined package copper wire rod rotational direction before the package, on the contrary, if the skew package orientation and cabling in the same direction as the oblique package will start for the cabling wire first reverse twist to make wire loose so inclined package prone to bad. However using reverse slant package wire relatively hard, bending performance difference. For those less cabling cores, core wire diameter is large, there is no isolation layer of wire can only be used with the cabling in the opposite direction.
6. external oblique package wire was out:
In oblique package wire was out before adoption down axis to prevent broken wires in charge out eyes caused breakage when die
Knitting-related design and calculation
Braided and inclined package similar to that in wire rod in a shielded against external electric field and magnetic fields influence, improve wire stem torsion directivity, and inclined package, aluminum foil has the following characteristics:
1. shielding the without direction.
2. good high-frequency shielding characteristics, suitable for high-frequency shielding.
3. adoption of the multiple layer masking, masking effects of up to 100%.
4. bending shielding characteristics without change.
1. weave the calculation formula:
Braiding angle tangent:
Braid coefficient:
Braided density:
Braided dosage:
H-braided pitch.
D-braided line diameter.
A-----woven into half the number of neutrons.
N-weaving and line number.
Α-braiding angle
2. weaving each parameter:
1. in accordance with the cable core diameter size, and weaving density size selected knitting machine types (16 or 24 high spindle speed knitting machine spindle)
2. Select adaptation of braided knitting machine of single wire (tinned or bare copper wire Φ Φ 0.08 m m m m, 0.10, Φ. 12 m m).
3. the density M. braided angle α. determination of the pitch H.
Note: the number of each ingot in 3-9 root, because the number of small woven disconnection and elements too much makes weaving layer within the same layer, braided copper conductor overlapping angles are typically 50-70 range, to increase productivity are braided to almost 70 by value, by the above formula parameters, use the budget together algorithm to determine the appropriate number of weaving, knitting, weaving the pitch angle, braided density. Computing section of braided calculation is using the above formulas, calculated using an enumeration method other structural design and calculation:
In cable design, sometimes in order to improve the quality of the need to join the other wires. In order to make wire round, stranded in the core wire; when you join the filler to prevent oxidation of the conductor stranded conductor surface coating adhesion b.t.a in order to improve the wire insulation charge out the conductor surface coating DOP or silicone oil, was out in the core wire surface drag talcum powder or MICA powder. The following classification in accordance with its role of different narrative:
1. filler design and calculation:
Filler yarn mainAnd PP ropes, design time mainly according to fill the gap size, wire performance requirements and material using the site, choose fill cotton yarn, PP rope or other.
Filler elements calculation
N = (S gap/S single root filling material) integer part
Filler content
W = single root weight * N * λ
Λ-----stranded for core wire into the coefficient of the wire.
2. the isolation level of the design and calculation:
Isolation material choice: the paper tape from the wire only; separate role in aluminum foil in the wire and the shielding effect of separated role. When the wire just separated, optional paper tape; otherwise it selects the aluminum foil. Sometimes in a number of high-performance communication line isolation layer using non-woven or foamed PP tape (such as SISC)
Technology way
In a separate layer in the manufacturing process, in order to save work, according to the case wrapped. drag-and packet-coated in three different ways. (Notes wrapped. drag-and packet is angle α = 40-60; longitudinal package angle α = 90).
Material usage
N-number for isolation layer.
T-for belt thickness.
Ρ---for isolation material density.
K-rate for belt overlap.
3. the relevant strand-in rate:
M-----for pitch diameter ratio.
H------as pitch.
D------stranded wire outer diameter.
Note 1: the above twisted into coefficient calculation for a process of calculation, in the actual calculation of the amount of time, you should consider the entire production process, so the total of stranded in coefficients may be multiple processes stranded in coefficient of product.
Note 2: the design calculation should take the lower value of the pitch range, in order to gain the maximum quota of stranded in coefficients (and in producing close to the maximum value of the pitch, you not only to increase efficiency and reduce the normal production of material consumption).
Electrical performance computing part
With contemporary electric communication business booming, the transmission signal wires and cables with electrical performance requirements are also getting higher and higher, so communication wire structure design, wire and electrical performance should be a focus on the object, the following section describes common communication wire basic electrical performance calculation method:
Foam insulated equivalent dielectric constant calculation formula:
Foam insulation is a combination of insulation, mainly in order to reduce the equivalent dielectric permittivity, improve wire electrical performance. Foam insulated media equivalent dielectric constant is between air insulation and plastic insulation dielectric constant, between the design process can use the following two methods to the foam insulation dielectric permittivity of equivalent.
Method (1):
Ε-media materials of equivalent dielectric constant
P-foaming degree%, which represents the foam medium, all small bubble size and insulation ratio of the total volume.
(2):
D-----foam medium weight
D material-media materials themselves that proportion
Ε e-----solid insulation dielectric constant
Ε------foam insulation dielectric constant
Symmetric cables structure calculation:
Symmetrical communication cable is composed of many insulated conductors, synthesis via twisted pair cable core and sheath of the package to the composition, cable pair or pairs with the same diameter and the same structure of two insulated conductors on symmetric permutations, so called symmetric cables. Symmetric cables of conductive core is used to guide the direction of electromagnetic wave transmission, so first of all requires conductive properties, to have good flexibility and sufficient mechanical strength, but also should consider its processing, and use of convenience.
The following points once transmission parameters and secondary transmission parameters to describe the main symmetrical cables: electrical performance
1. the first transmission parameters
R.L.C.G called cable line of transmission parameters: these parameters and the transmission of electromagnetic wave voltage and current regardless of size, and the cable material structure and current of frequency:
1.1 effective resistance.
Effective resistance is when Exchange flow through symmetric circuit resistance, including DC resistance and through the exchange of additional resistance.
R r = R turn straight +
R R o + turn = R set + R gold
Λ-total of stranded in coefficients
Ρ-conductive core of resistivity ohm * mm2/m
L------cable length m
S------conductive core of cross-sectional area mm2
D-conductive core diameter mm
A-loop distance between the two conductors Center mm
K-------Vortex factor
U------for magnetic permeability
Σ-----conductivity
1.2 symmetrical cable inductance
When the loop passes to AC, you in the loop ofconductive core and loop around flux, in conductive core within the magnetic flux within called, in conductive core, called the foreign flux. caused by inductively to the flux and vortex's current ratio, therefore, appropriate to the inner and the outer magnetic flux flux with inner inductance L inner and outer inductance L, total inductance for L = L + L within. when symmetric circuit has a shield, symmetrical cable shielded Loop inductance L, in addition to the inductance L, there are shield to the transmit circuit brings additional inductance.
1.2.1. screened:
(H/Km)
Λ-total of stranded in coefficients
D-conductive core diameter mm
A-loop distance between the two conductors Center mm
K-------Vortex factor
U------for magnetic permeability
Σ-----conductivity
The Q (X) is calculated as described in the communication cable 54 pages
1.2.2. the shield:
(H/Km)
Λ-total of stranded in coefficients
D-conductive core diameter mm
A-loop distance between the two conductors Center centsM
K-------Vortex factor
U------for magnetic permeability
Σ-----conductivity
1.3 symmetrical cable capacitance
Cable to the back of capacitance and capacitance of the capacitor is generally similar to. both conductive core equivalent to two electrode, conductive
Core insulation between equivalent of capacitor plate between media.
When the loop of the two conductive core with equal amounts of specific charge, the charge power Q and two conductive core potential difference between U ratio, as the circuit of capacitor that C = U/Q.
Symmetric cables circuit capacitance is more complex, because cable often include many lines, and the outside and a shield or metal casing, all any adjacent conductors or between core and the shielding layer. metal sleeve will have the presence of the capacitance of the capacitor circuit-refers to the sum of the parts.
Symmetric cables circuit capacitance has two parts: the work of capacitance and capacitance. one transmission parameters of capacitor capacitance that work (work-capacitor capacitance for the portion of the form).
Unshielded symmetrical cable (UTP) capacitance press-type calculations:
F/m
Applies to two conductors around a parallel, and no other lines on the ideal situation.
A-two conductors of Center distance (mm)
D-Center conductor diameter (mm)
Ε e-insulation materials of equivalent dielectric constant
For more on the structure of symmetric cables, should consider the effect of the stranded wire and adjacent lines and other factors, its capacitance
Formula:
F/m
Λ-stranded coefficient
Φ-correction factor, considered proximity line or lines on the screen for capacitance effects.
Correction coefficient of φ and the relationship between structural parameters.
Shielded twist
Unshielded twist
A-------symmetric Center distance of the cable conductor
DS-shield diameter (mm)
D2-twisted pair of outer diameter (mm)
D1-insulated cores of outer diameter (mm)
1.4. symmetric cables insulated with conductivity.
Insulated conductance G this parameter describes the cable core insulation quality and electromagnetic energy online core insulation for wear. insulation dielectric conductivity is determined by the nature of the decision, that is, the volume of the dielectric insulation resistance coefficient and dielectric loss angle tangent to decide. insulation conductance G by DC insulation conductance G0 and AC guide G ~ combination. calculated as follows:
G=G0+G~
G~=ω*Ctg(δ)
G0------DC loss
G ~------exchange losses
Ω------current frequency
C-------capacitance
Tg (δ)---dielectric loss angle tangent
2. the second transmission parameters
Secondary transmission parameters for characterization of transmission line of argument, it includes the characteristic impedance ZC, attenuation constant α, and phase shift constants.
2.1 characteristic impedance
Characteristic impedance is electromagnetic wave propagation along uniform cable line without reflecting the impedance, and its value only and line of transmission parameters and the frequency of electric current, and has nothing to do with the length of the lines, and transmission voltage and current size and has nothing to do with negative planted impedance:
Unshielded symmetrical cable (UTP):
Europe
Europe
Shielding symmetrical cable (STP):
Europe
Europe
When a symmetric Cable Center conductor is wire structure, shielding for weaving, the formula is: Europe
K3 is braided and empirical correction coefficient, value 0.98 ~ 0.99
Correction factor for conductor K1, conductor construction correction factor K! and the relationship between the number of conductors:
Strand conductor wire elements within the
N
1
3
7
12
19
Inner conductor structure of correction factor
K1
1.000
0.871
0.939
0.957
0.970
Strand conductor wire elements within the
N
27
37
50
70
90
Inner conductor structure of correction factor
K1
0.976
0.980
0.983
0.986
0.988
2.2 attenuate:
RF cable attenuation is the most important one of the parameters, it reflected electromagnetic energy along the cable transmission loss of the size of the cable attenuation said cable in traveling wave State when the transmit power or voltage loss level.
Symmetric cables in RF attenuation of high-frequency can be calculated as follows: simplified formula
2.2.1. the unshielded symmetric cables:
2.2.2. shielding symmetric cables:
F-----frequency
De-stranded conductors--electrical equivalent diameter
D-stranded conductor diameter
Ds--shielded inner diameter
A-symmetric Center distance of the cable conductor
E-ε-insulated equivalent dielectric constant
Tg (δ)---insulated equivalent dielectric loss angle tangent
Kp1-conductor of the radio frequency RF cable resistance coefficient see structural design in sheets4.5
Kp2-shielded RF resistance coefficient see RF cable structure design in sheets 4.5
Ks-------strand conductor resistance coefficient 1.25
KB-a-braid shield of resistance coefficient 2.0
K3------braid coefficient of impedance 0.98 ~ 0.99
Coaxial cables of electrical parameters calculation:
A loop is coaxial cables coaxial for, it is not on the groundSymmetrical in metal tubes (called the outer conductor), configure another round conductor (known as the inner conductor), dielectric insulation between each other and stay to axial heavy to match, so the line on symmetric coaxial. Coaxial cable can be used to open multiple planting wave communication or transmission of television programmes, you can also use a coaxial cable to transmit high digital data information (such as UL2919 screen lines)
1. the first transmission parameters:
Coaxial cable of a transmission parameters key with current of frequency and cable D/d changes.
(1) effective resistance, with the frequency of grows. internal and external conductor diameter than no direct relationship.
(2). the increase of the frequency inductance and decrease, with inner and outer conductor diameter ratio grows.
(3), capacitance and frequency vary with the diameter ratio of increase and decrease.
(4). the electrical conductivity and frequency proportional to basically, with the diameter of the increase and decrease.
The specific calculation formula is as follows:
1.1. effective resistance:
Coaxial cable of effective resistance including inner conductor of effective resistance and outer conductor of effective resistance, when the inner and outer conductors are copper conductor, effective resistance in General:
(Ohm/km)
1.2 effective inductance:
Coaxial Loop inductance from inside to outside of the inner conductor-inductance and inner and outer conductors consisting of external inductance between, when the inner and outer conductors are copper, Loop inductance:
(Heng/km)
Coaxial cables of electrical parameters calculation:
A loop is coaxial cables coaxial for, it's on to asymmetrical in metal tubes (called the outer conductor), configure another round conductor (known as the inner conductor), dielectric insulation between each other and stay to axial heavy to match, so the line on symmetric coaxial. Coaxial cable can be used to open multiple planting wave communication or transmission of television programmes, you can also use a coaxial cable to transmit high digital data information (such as UL2919 screen lines)
1. the first transmission parameters:
Coaxial cable of a transmission parameters key with current of frequency and cable D/d changes.
(1) effective resistance, with the frequency of grows. internal and external conductor diameter than no direct relationship.
(2). the increase of the frequency inductance and decrease, with inner and outer conductor diameter ratio grows.
(3), capacitance and frequency vary with the diameter ratio of increase and decrease.
(4). the electrical conductivity and frequency proportional to basically, with the diameter of the increase and decrease.
The specific calculation formula is as follows:
1.1. effective resistance:
Coaxial cable of effective resistance including inner conductor of effective resistance and outer conductor of effective resistance, when the inner and outer conductors are copper conductor, effective resistance in General:
(Ohm/km)
1.2 effective inductance:
Coaxial Loop inductance from inside to outside of the inner conductor-inductance and inner and outer conductors consisting of external inductance between, when the inner and outer conductors are copper, Loop inductance:
(Heng/km)
1.3 coaxial cable capacitance:
With no external electric field on coaxial cable, coaxial capacitance on work to coaxial on part of the inner and outer conductors, capacitor capacitance calculation by cylindrical capacitor capacitance formula to calculate:
Dw-outer conductor structure of correction factor (the ideal outer conductor Dw = 0, a non-ideal outer conductor Dw = weave outer conductor diameter in-line)
K1-inner conductor structure of correction factor,
D1-coaxial cable outer conductor diameter (mm)
1.4 insulated conductance:
Coaxial to the insulated conductors G consists of two parts: one is made of insulated media polarization induced by AC guide G ~, another part is due to the defective insulation from direct import G0:
G=G0+G~
G~=ωCtg(δ)
G0------DC loss
G ~------exchange losses
Ω------current frequency
C-------capacitance
Tg (δ)---dielectric loss angle tangent
2. the second transmission parameters:
Secondary transmission parameters for characterization of transmission line parameters, it includes the characteristic impedance ZC, attenuation constant α, and phase shift constants.
2.1. coaxial impedance:
2.1.1. for oblique bags, aluminum foil coated can be approximated as ideal outer conductor, calculated as follows:
2.1.2. the weave outer conductor, stranded wire inner conductor is calculated as follows:
D---outer conductor diameter
D-inner conductor diameter
Dw-braided conductor diameter
K1-conductor construction correction factor
2.2 coaxial cable attenuation calculation formula:
Α R-conductor resistance loss caused by the decaying, conductor attenuation (resistance attenuation)
When the inner and outer conductors are cylindrical conductor:
db/km
When the inner conductor is wire, outer conductor is woven:
db/km
D.d-outer conductor diameter. inner conductor diameter
K1-conductor construction correction factor
Ε-insulating dielectric constant
KS-strand cables resistance due to shoot ping increased coefficient, KS = 1.25
KB-braided cable resistance due to shoot ping increased coefficient
Dw-weave outer conductor diameter in-line
KP1 and KP2-represent the outer conductor and standard soft copper is not at the same time cause radio frequency resistance increase or decrease the
The coefficient.
Braid coefficient calculation is also available as KB method to find out:
M-for weaving spindles
N-line for each ingot braided conductor elements in
Β-angle for weave (braided wires and cables for the angle between the axis direction)
Α G-dielectric loss suffered as a result of decaying, known as media attenuation (electricImport attenuation)
T g σ e-equivalent dielectric loss angle tangent
Ε e-------equivalent dielectric constant
2.3 delay:
Latency refers to the signal along the cable transmission, its unit length of the delay time.
Coaxial cable of delay and cable size-independent, just depends of dielectric constant.
SEC/m
V-signal on the propagation speed of the cable
Ε e-equivalent dielectric constant