what is the Braid Angle and Shield Coverage ?

The braid angle and the percent coverage of the braid shall be determined by the following formula:
Tan α = 2 π (D + 2d1) P/C
K = 100 (2F-F2)

Where:
K = percent coverage
F = EPd2/sin α
P = picks per inch of cable length
α = angle of braid with axis of cable
E = number of strands per carrier
d1 = diameter of one of the round shield strands or thickness of flattened strand
d2 = diameter of one of the round shield strands or width of flattened strands
D = diameter of cable under shield
D = Gb ( for cables with no fillers, cable factor from column G of Table 3-6)
D = Ab (for cables with fillers to round, use cable factor A of Table 3-6)
C = number of carriers
n = number of basic wires (see Table 3-6)
b = basic wire diameter

 


What is the percentage of optical coverage of a screen shall be calculation ?

D is the average diameter of the screen (diameter under the screen plus 2 d in mm);
d is the nominal wire diameter in mm (used for the screen);
S is the lay length of wires in the screen in mm;
m1 is the number of bunched wires in one direction (number of small spools);
m2 is the number of bunched wires in opposite direction (number of small spools);
n1, n2 are the number of wires used for each bunch

Calculating the Shield Coverage and Braid Angle

Simple formulas can be used to calculate shield coverage and braid angle. The shield should consist of a woven braid using strand material specified in the cable specification. Coverage should not be less than 85% for most cables, but may be increased to 90%. The angle of the braid with the axis of the cable should lie between 20º and 40º for diameters up to .600 inch (15.2 mm). For diameters larger than .600 inch (15.2 mm), the braid angle may be greater than 40º. Percent coverage, K, and angle of braid, a, should be calculated as follows:

K = (2F – F2) x 100
F = NPd/Sin a
a = Tan -1 (2π(D +2d) P/C)
where
F = Fill or space factor
K = Percent coverage
N = Number of wires per carrier
P = Picks per inch of cable length
d = Diameter of individual braid wire
in inches
a = Angle of braid with axis of cable
D = Diameter of cable under the
shield in inches
C = Number of carriers

You are not allowed to view links. Register or Login

    Filament diameter: the diameter of the individual metallic wires a braid is composed of. Another expression for filaments is "ends" (see figure below).

    Number of filaments in one carrier: number of individual wires (ends) which are grouped to a carrier (see figure below).

    Number of carriers:  number of carriers, usually 16 for the most telecommunication braided cables (see figure below).

The product of the three parameters from above specifies a length. This length is not allowed to exceed the double of the screen's circumference, which is implicitly defined by the Insulator inside setting (see figure of dialog box above). The fourth characteristic specifies the weaving style and can be expressed by one of the following three parameters:

    either Braid angle: the angle formed by the carriers with the longitudinal axis of the cable (see figure below).

    or Optical Coverage: the percentage of screen surface which is filled by metallic wires to the overall surface of the screen (= metal wires + apertures, see figure below)

    or Picks per unit length: the number of carrier crossing points per longitudinal unit length (see figure below).