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Inrush current, input surge current, or switch-on surge is the maximal instantaneous input current drawn by an electrical device when first turned on. 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.
The current into a capacitor is known to be = (/): the peak inrush current will depend upon the capacitance C and the rate of change of the voltage (dV/dT). The inrush current will increase as the capacitance value increases, and the inrush current will increase as the voltage of the power source increases.
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).
The internal resistance of low-power transformers in linear power supplies usually limits the peak current each cycle and thus gives a better power factor than many switched-mode power supplies that directly rectify the mains with little series resistance. Inrush current
Ripple (specifically ripple current or surge current) may also refer to the pulsed current consumption of non-linear devices like capacitor-input rectifiers. As well as these time-varying phenomena, there is a frequency domain ripple that arises in some classes of filter and other signal processing networks.
Inrush current or input surge current or switch-on surge is the maximum, instantaneous input current drawn by an electrical device when first turned on. Inrush current usually lasts for half a second, or a few milliseconds, but it is often very high, which makes it dangerous because it can degrade and burn components gradually (over months or ...
The surge is defined by the Combination Wave Generator's open-circuit voltage and short-circuit current waveforms, characterized by front time, duration, and peak values. With an open circuit output, the surge voltage is a double exponential pulse in the form of k ( e − α t − e − β t ) {\displaystyle k(e^{-\alpha t}-e^{-\beta t})} .
In addition to the current limiting function, the device serves to filter out spikes of current [7] and may also reduce injection of harmonic currents into the power supply. The most common type is designed for three-phase electric power, in which three isolated inductors are each wired in series with one of the three line phases. [8]