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For example, the power-handling ability of a resistor may be greatly derated when applied in high-altitude aircraft to obtain adequate service life. A sudden fail-open fault can cause multiple secondary failures if it is fast and the circuit contains an inductance ; this causes large voltage spikes , which may exceed 500 volts.
Various resistor types of different shapes and sizes. A resistor is a passive two-terminal electrical component that implements electrical resistance as a circuit element. In electronic circuits, resistors are used to reduce current flow, adjust signal levels, to divide voltages, bias active elements, and terminate transmission lines, among other uses.
Wire leads in low power wirewound resistors are usually between 0.6 and 0.8 mm in diameter and tinned for ease of soldering. For higher power wire-wound resistors, either a ceramic outer case or an aluminum outer case on top of an insulating layer is used.
An AC FCL is usually made from wire wound non-inductively; otherwise the inductance of the device would create an extra constant power loss on the system. [citation needed] Inductive FCLs come in many variants, but the basic concept is a transformer with a resistive FCL as the secondary. In un-faulted operation, there is no resistance in the ...
A ground fault (earth fault) is any failure that allows unintended connection of power circuit conductors with the earth. [citation needed] Such faults can cause objectionable circulating currents, or may energize the housings of equipment at a dangerous voltage. Some special power distribution systems may be designed to tolerate a single ...
Nichrome, a non-magnetic 80/20 alloy of nickel and chromium, is the most common resistance wire for heating purposes because it has a high resistivity and resistance to oxidation at high temperatures, up to 1,400 °C (2,550 °F). When used as a heating element, resistance wire is usually wound into coils.
For wound components such as inductors and transformers, there is additionally the important effect of parasitic capacitance that exists between the individual turns of the windings. This winding parasitic capacitance will cause the inductor to act as a resonant circuit at some frequency, known as the self-resonant frequency, at which point ...
Coils are typically wound with enamelled copper wire, sometimes termed magnet wire. The winding material must have a low resistance, to reduce the power consumed by the field coil, but more importantly to reduce the waste heat produced by resistive heating. Excess heat in the windings is a common cause of failure.