FED-STD-228A
Method 1631.1
18 APRIL 2014
ANGLE OF BRAID, METAL ARMOR
1. SCOPE
1.1 This method is intended for use in determining the angle between the wire of braided metal armor
and the axis of the insulated wire or cable.
2. SPECIMEN
2.1 The specimen should be a piece of the inspection unit at least 12 inches in length from which any
covering over the armor has been removed.
3. APPARATUS AND REAGENTS
3.1 The apparatus and reagents shall be as described in the methods referenced in 4.
4. PROCEDURE
4.1 The specimen shall be free from mechanical damage. The number of picks per inch of the armor
shall be determined as described in method 8011 and the value recorded as P.
4.2 The number of carriers in the armor shall be determined as described in method 8021 and the value
recorded as C.
4.3 The armor shall be removed from the specimen and the diameter over the core (assembly under the
armor) shall be determined as described in method 1111 and the value recorded as D.
4.4 The thickness of the armor shall be determined as described in method 1221 and the value recorded
as T.
5. RESULTS
5.1 Calculation. The tangent of the angle of the metal armor at any place shall be calculated as follows:
Tangent of angle=2šP(D+T)/C
where:
P=the number of picks per inch
D=the diameter over the core, inches
T=the thickness of the armor, inch
C=the number of carriers in the armor
2š=6.28
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