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An inrush current limiter is a device or devices combination used to limit inrush current. Passive resistive components such as resistors (with power dissipation drawback), or negative temperature coefficient (NTC) thermistors are simple options while the positive one (PTC) is used to limit max current afterward as the circuit has been operating (with cool-down time drawback on both).
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.
Inrush current can also be reduced by inrush current limiters. Negative-temperature-coefficient (NTC) thermistors are commonly used in switching power supplies, motor drives and audio equipment to prevent damage caused by inrush current. A thermistor is a thermally-sensitive resistor with a resistance that changes significantly and predictably ...
If the example circuit from before is used with a pre-charge circuit which limits the dV/dT to less than 600 volts per second, then the inrush current will be reduced from 670 amperes to 7 amperes. This is a "kinder and gentler" way to activate a high voltage DC power distribution system.
Current limiting reactor. The main motive of using current limiting reactors is to reduce short-circuit currents so that circuit breakers with lower short circuit breaking capacity can be used. They can also be used to protect other system components from high current levels and to limit the inrush current when starting a large motor. [5]
An NTC is commonly used as a temperature sensor, or in series with a circuit as an inrush current limiter. With PTC thermistors, resistance increases as temperature rises; usually because of increased thermal lattice agitations, particularly those of impurities and imperfections.
Wound-rotor motors can be started with low inrush current, by inserting high resistance into the rotor circuit; as the motor accelerates, the resistance can be decreased. [ 1 ] Compared to a squirrel-cage rotor , the rotor of the slip ring motor has more winding turns; the induced voltage is then higher, and the current lower, than for a ...
Figure 1: An ideal current source, I, driving a resistor, R, and creating a voltage V. 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 ...