Armour resistance

Nominal conductor area (mm ) Single core in trefoil 3 and 4 cores Approximate armouring resistance ... 

Nominal Current conductor rating area (mm ) at 40°C (amps) 3-core conductor GSWB armouring resistance (ohms) Ra... 

Once the threat has been defined, the impact conditions have been established. The next step is to assess how well personal armour resists attack. What can it stop What does it allow through What are the conditions behind the armour What areas of the body are uncovered ... 

Estimation of armour resistance depends on what can be stopped arrd what is let through. It combines knowledge of areas that are covered arrd uncovered. Importantly, the designer must specify the conditiorrs behirtd armour during an attack. 

Specification for 600/1000V and 1900/3300 V armoured electric cables having thermosetting insulation Fire resisting characteristics of electric cables Performance requirements, sample and lest conditions - BS 5467/1997... 

Shell for penetrating armour have heavier steel bodies with at least the nose of specially hardened metal. The proportion of explosive is smaller and it must also be exceptionally resistant to detonation by impact, so that the shell can penetrate the armour before the explosive is detonated by the fuze. Suitable fillings are therefore TNT or desensitised TNT/RDX mixtures. The latest armour-piercing projectiles for anti-tank use contain no explosive, but have high density cores made of tungsten. 

In 1889 James Riley of Glasgow drew attention to the various special properties of nickel steels. This interested, amongst others, the American Naval Authorities, who, in 1891, purchased plain steel plates from British and French manufacturers and nickel steel plates from Le Creusot works of Schneider in France. On testing these, the last named proved much more resistant to projectile attack than the others. The results attracted world wide attention and the introduction of alloy steels for naval armour plate dates from this time. 

Steel wire armour as opposed to steel wire braid has lower electrical impedance for a given length of cable. This is an important benefit in networks that are solidly earthed at their power source. Some special applications that require as low an impedance as is practical to achieve in the cable have some of the armour wires replaced by copper wires. Hence the parallel circuit consisting of the steel and copper wires has a lower total impedance than the steel wires on their own. The impedance of the armouring, with or without the copper wires, is predominantly resistive and so the inductive reactance at the power frequency can therefore be ignored. 

There may be additional materials within the cable such as semiconductor screens for the coreinsulation interface jute, hessian or bitumen for giving extra water resistance to the wire armouring ... 

Conductors Insulation Screening of conductors and insulation Inner and outer sheathing Armouring wires and braids Fire resistance flame, retardance and smoke emission... 

The driving voltage is the phase voltage. The sonrce impedance Zs is fixed and is usually that of the upstream supply cables and transformers, or generators (or the output impedance of supplies such as a UPS). Zs can often but not always be neglected. The cable conductor impedance Z is easily calculated from the cable data for one phase conductor and its route length. Similarly the armouring impedance Z can be calculated from the data, which is predominantly resistive for most types of power cables. For typical cable data see the tables in Chapter 9. 

BS7846 Electric cables. 600/1000 V armoured fire-resistant cables having thermosetting insulation and low emission of smoke and corrosive gases when affected by fire. 

AI.Oj Wear resistance Wear parts (thread guides), armouring, bioceramics, electronic components... 

Protective clothing - body armour - part 2 Bullet resistance requirements and test methods. ISO Standard ISO/FDIS 14876-2, International Organization for Standardization, Geneva, Switzerland, 2002. 

Thermal insulation pads, glass handling jaws, vacuum pump insulators, fixture,s and components in X-ray equipment, asbestos replacement, antenna insulators, precision crystal holders, abrasion resistance piece tools, body armour, other low load-bearing structural components. 

Anti-stab protection, on the other hand, relies on tightly woven structures that offer protection from sharp pointed objects, with or without sharp cutting edges. Even though stab-resistant armour defeats slash attempts, it is impractical to provide stab protection to the arms, neck, shoulder, and thigh regions because of the thickness and stiffness required if armour materials are to withstand the force of a stab attack. Slash resistant armours, in contrast, need not be excessively bulky and/or stiff. They can be more flexible and lighter as the maximum load exerted by a slash is approximately 25% of the loads measured in stab attacks. 

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