What causes inrush current?

Inrush current is the instantaneous high input current drawn by a power supply or electrical equipment at turn-on. This arises due to the high initial currents required to charge the capacitors and inductors or transformers. These currents can be as high as 20 times the steady state currents.

How inrush current is reduced in Mosfet?

When the MOSFET turns on, inrush current IRUSH flows to charge this capacitor. This inrush current is reduced by increasing the series gate resistor Rgate. When the gate resistance increases, the rising output current becomes less pronounced.

How does an inrush current limiter work?

The nature of the inrush current limiter to self-heat as an increasing amount of current is applied, which generates heat, causes resistance to drop, allowing the current to flow freely. This self-heating effect is the underlying reason that allows the inrush current limiter to work effectively.

How can we reduce the starting current of an induction motor?

Starting current of three phase induction motor can be reduced to safe value by including:

1. resistor in rotor circuit at instant of starting.
2. capacitor in stator circuit at instant of starting.
3. capacitor in rotor circuit at instant of starting.
4. inductor in rotor circuit at instant of starting.

What do you mean by inrush current?

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.

Does inrush current cause voltage drop?

Starting currents A known cause of small voltage drops are the starting or inrush currents for capacitors, motors and other devices. The inrush current leads to a voltage drop across the impedances Z and Z1.

How do I choose my inrush current limiter?

Inrush Current Calculators are the best way to measure the resistance versus temperature curve to get the right Inrush Current Limiter. Switching power supplies, DC motors, and lighting ballasts can develop extremely high peak inrush current at turn-on unless you implement inrush current protection.

Where is inrush current limiter used?

A typical application of inrush current limiters is in the input stage of non-power factor corrected switching supplies, to reduce the initial surge of current from the line input to the reservoir capacitor. The most popular application is the inrush protection of the AC current in switching power supplies (SPS).