## 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.

## What is maximum allowable inrush current?

Inrush current limiters are available in a wide range of initial resistance levels and current carrying capabilities. Ametherm produces inrush current limiters ranging from . 2 to 220 ohms of initial resistance. Some designs are rated for less than one ampere while other are rated for up to 36 amperes.

How do you limit an inrush current motor?

One is to use a soft starter — a device that gradually increases supply voltage to the motor terminals during startup, thus lowering inrush current and controlling startup torque. Similarly, a variable frequency drive reduces inrush current by controlling the voltage supplied to the motor.

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).

### How do you protect surge current?

Inrush current protection can be provided by an active circuit that uses a combination of power resistors, thyristors, and triacs. Active circuits are generally expensive and difficult to design. Another option for inrush current protection is an NTC thermistor.

### How can the starting current of a motor be reduced?

Some of the techniques used to reduce the starting current of a squirrel induction motor:

1. Soft starting (voltage control)
2. Variable Frequency Drives (Voltage and frequency control)
3. Star/Delta Starting.
4. Stator impedance and/or resistance starting.
5. Autotransformer Starting.

How does 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.

Can inductor reduce inrush current?

Reducing input inrush current (DC/DC power supplies) A more common solution is to add an inductor to limit the inrush current.

#### How many amps will trip a 50 amp breaker?

A 50 Amp split phase 120/240 VAC service should be capable of 50 Amps per leg for a total ampacity of 100 Amps. It’s true that you have 50 Amp on each leg for 100 Amp total, but if you get up to 45 Amp continuous on one leg, you will trip the breaker.