Wire Calculations Formulas
Shield Coverage
Braided Shield Tan a= 2pi(D + 2d)P/C
Where: D = Diameter under sheild, inches
d = Diameter of 1 strand, inches
P = Picks per inch
N = Number of strands per carrier
a = Shield angle, degrees
K = Percent coverage
C= Number of carriers
When: K = (2F - F(squared)) x 100
and:
F = NdP / Sin a
Shield Resistance
The D.C. resistance for braided shields can be calculated using the following equation:
R = dR/Cos a (NC)
Where: R = D.C. resistance, ohms/unit length
dR = D.C resistance of 1 strand end, ohms/unit length
a = Braid angle, degrees
N = Number of strand ends in one carrier
C = Number of carriers
Wire Calculations
Insulation Weight: (((D(squared) -d(squared))/2) x K x G) = (lb/M')
Where: D= Diameter over insulation (inches)
d= Diameter over conductor (inches)
K= Constant 680
G= Specific gravity of insulation material
Shield Weight: ((NxCxW)/cosa) x 1.03 = (lb/M')
Where: N= No. of ends per carrier
C= No. of carriers
W= Weight of one shield strand (lb/M')
a= Braid angle
Jacket Weight: (((D(squared) -d(squared))/2) x K x G) = (lb/M')
Where: D= Diameter over the jacket (inches)
d= Diameter under the jacket (inches)
K= Constant 680
G= Specific gravity of jacket material
Tensile Strength Calculations for Insulation
Tube Insulation: PSI = F/ ((OD(squared) -ID(squared)) x .7854)
Where: F= Breaking force of specimen in pounds
OD=Diameter over the insulation (inches)
ID=Inner dimension of insulation or conductor OD (inches)
Sheath Insulation
Using 1/4" wide dumbell sample
PSI = F/(T x .25")
Where: F= Breaking force of specimen in pounds
T= Wall thickness of specimen (inches)
Tensil Strength Calculations for Conductor
Solid Conductor For Single Strand: PSI = F/((D(squared) x .7854)
Where: F= Breaking force of specimen in pounds
D= Diameter of solid conductor or single strand (inches)
Stranded Conductor
PSI =F/((d(squared) x No. of strands x .7854)
Where: F= Breaking force of specimen in pounds
d= Average diameter of a single strand(inches)