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In all cases, electromigration can cause changes in dimensions and parameters of the transistor gates and semiconductor junctions. Mechanical stresses, high currents, and corrosive environments forming of whiskers and short circuits. These effects can occur both within packaging and on circuit boards. Formation of silicon nodules.
A relay Electromechanical relay principle Electromechanical relay schematic showing a control coil, four pairs of normally open and one pair of normally closed contacts An automotive-style miniature relay with the dust cover taken off. A relay is an electrically operated switch. It consists of a set of input terminals for a single or multiple ...
An asymmetric or unbalanced fault does not affect each of the phases equally. Common types of asymmetric fault, and their causes: line-to-line fault - a short circuit between lines, caused by ionization of air, or when lines come into physical contact, for example due to a broken insulator.
A short circuit is an abnormal connection between two nodes of an electric circuit intended to be at different voltages. This results in an electric current limited only by the Thévenin equivalent resistance of the rest of the network which can cause circuit damage, overheating, fire or explosion.
Reclosers can then apply a fuse burning policy, where they remain closed for a short period to allow fuses on lateral lines to burn, isolating the fault. If the fault is not cleared, the recloser trips open again. This same policy can be used to deliver energy to fault sites to burn the fault off the line.
Whiskers can be small enough to pass through air filters and can settle inside equipment, resulting in short circuits and system failure. [ 8 ] Tin whiskers do not have to be airborne to damage equipment, as they are typically already growing directly in the environment where they can produce short circuits, i.e., the electronic equipment itself.
This type of arc flash mitigation device operates rapidly within a few milliseconds, creating a three-phase short-circuit to ground, which safely redirects fault currents away from the location of the arc flash. Upon activation by an external relay, a fast-moving contact pin makes physical contact with the energized bus, creating the short circuit.
The effect of too high short-circuit current is discussed in the previous section. The short-circuit current should be around 20 times the rating of the circuit to ensure the branch circuit protection clears a fault quickly. Quick disconnecting is needed, because during a line-to-ground short circuit the grounding pin potential on the power ...