Inrush current, input surge current or switch-on surge refers to the maximum, instantaneous input current drawn by an electrical device when first turned on. For example, incandescent light bulbs have high inrush currents until their filaments warm up and their resistance increases. Alternating current electric motors and transformers may draw several times their normal full-load current when first energized, for a few cycles of the input waveform. Power converters also often have inrush currents much higher than their steady state currents, due to the charging current of the input capacitance. The selection of overcurrent protection devices such as fuses and circuit breakers is made more complicated when high inrush currents must be tolerated. The overcurrent protection must react quickly to overload or short circuit but must not interrupt the circuit when the (usually harmless) inrush current flows.
... An inrush current limiter is a device or group of devices used to limit inrush current ...
... An inrush current limiter is a component used to limit inrush current to avoid gradual damage to components and avoid tripping the supply's fuse or circuit breaker ... (NTC) thermistors and fixed resistors are often used to limit inrush current ... NTC thermistors can be used as inrush-current limiting devices in power supply circuits when placed in series with the circuit being protected ...
... A resistor in series with the line can be used to limit the current charging input capacitors ... Inrush current can also be reduced by inrush current limiters ... supplies, motor drives and audio equipment to prevent damage caused by inrush current ...
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