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HOME > SZ News>Industry News>SZ News>Industry News

Copper Wires are Therefore Safer and More Reliable

2017-05-18 10:25    hits:763
Abstract:But because of electrical failures involving the wiring, it became credible that while a affiliated run of copper wire does not present a problem, if that wire is affiliated to outlets and ablaze switches -- and even to other affairs in alliance boxes --

But because of electrical failures involving the wiring, it became credible that while a affiliated run of copper wire does not present a problem, if that wire is affiliated to outlets and ablaze switches -- and even to other affairs in alliance boxes -- the affiliation can adulterate and become a blaze hazard.

Copper wires resist the mechanical deformation (creep) all metals experience when subjected to stress, and are therefore safer and more reliable

Creep is the plastic deformation of metal conductors that occurs when these are subjected to an external stress (pulling force). Creep depends on the stress level, its duration and the temperature, and is different for each metal. Creep is irreversible, unlike elongation which is elastic and reverses as soon as the external force is removed.

Why is creep an issue?

Creep is an issue for insulated electrical wires and cables as these are subjected to external stresses through e.g. a) pulling during cable laying b) thermal cycles and c) electromagnetic forces.

Creep is also an issue at terminations, where a screw can squeeze and deform the conductor, reducing the contact pressure and leading to increased joint resistance, a loose connection, oxidation, arcing and overheating.

Similarly creep is an issue for enameled wires, for example those used in distribution transformers. Frequent energization of distribution transformers is unavoidable in weak power networks and power deficient areas, due to various reasons such as extension and maintenance works, scheduled and unscheduled load shedding, faults, and the power demand exceeding generation. Distribution transformers experience large magnetic inrush currents when switched on, which can be several times the rated operating current. These currents produce excessive mechanical stresses and intense localized heating (hot spots). Each time this occurs, the winding conductors creep by a small amount. Over a period of years, this repeated creeping causes the winding conductors to bunch closer to each other than the allowable minimum safety clearances specified by standards. If the elongation in the wire is more than the allowable gap between two layers of the winding then an insulation rupture occurs leading to an inter-turn short-circuit and thus to a failure of the transformer.