Sunday, April 22, 2012

Wire Processing and Wire Integrity Testing

Wires and cables have lifetime limitations due to normal material degradation, vibrations and stresses that they come under, and the collateral damage that occurs during normal maintenance. Aging wiring can result in degraded performance due to accumulated damage from long-term exposure to chemical, thermal, electrical and mechanical stress.

These failures often appear as broken conductors, corrosion and damaged insulation which can disrupt electrical signals and /or lead to arcing. Arcing is a form of short circuit that arises when wiring with ruptured insulation come in contact with metallic structures or other exposed wiring in moisture. When this occurs, there is usually a high energy flashover which could lead to a fire even before the circuit breaker is triggered. Arcing also increases signal loss and distortion on live signal through the wire.

Electric arcing occurs not only as an electrical failure but as a contributor to all other failure modes. Maintenance and assurance of the integrity of the wiring is very challenging due to the risk involved in accessibility e.g nuclear plants, as well as due to the high density of wiring network e.g onboard aircraft and ships. For instance, modern jet transport aircraft contains hundreds of kilometres of wires.