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Current limiting is the practice of imposing a limit on the current that may be delivered to a load to protect the circuit generating or transmitting the current from harmful effects due to a short-circuit or overload. The term "current limiting" is also used to define a type of overcurrent protective device.
It necessitates the test of surge immunity in electrical or electronic equipment. IEC 61000-4-5 defines test set-up, procedures, and classification levels. In particular, it standardizes the required surge voltage and current waveforms for laboratory testing, with the "1.2/50-8/20 μs" impulse being the most frequently used surge waveform.
Current limiting reactors, once called current limiting reactance coils, were first presented in 1915. [2] The inventor of the current limiting reactance coil was Vern E. Alden who filed the patent on November 20, 1917 with an issue date of September 11, 1923. The original assignee was Westinghouse Electric & Manufacturing Company. [3]
NTC thermistors can be used as inrush-current limiting devices in power supply circuits when added in series with the circuit being protected. They present a higher resistance initially, which prevents large currents from flowing at turn-on. As current continues to flow, NTC thermistors heat up, allowing higher current flow during normal operation.
Electrical installations; Wiring practice by region or country; North American practice; United Kingdom practice; Regulation of electrical installations; BS 7671 UK wiring regulations; IEC 60364 IEC international standard; Canadian Electrical Code (CE Code) U.S. National Electrical Code (NEC) Cabling and accessories; AC power plugs and sockets ...
It is known as a current-limiting diode (CLD) or current-regulating diode (CRD). Internal structure. It consists of an n-channel JFET with the gate shorted to the source, which functions like a two-terminal current limiter (analogous to a voltage-limiting Zener diode). It allows a current through it to rise to a certain value, but not higher.
A current source is an electronic circuit that delivers or absorbs an electric current which is independent of the voltage across it. A current source is the dual of a voltage source . The term current sink is sometimes used for sources fed from a negative voltage supply.
In electromagnetism, current density is the amount of charge per unit time that flows through a unit area of a chosen cross section. [1] The current density vector is defined as a vector whose magnitude is the electric current per cross-sectional area at a given point in space, its direction being that of the motion of the positive charges at this point.