How to measure the INRUSH current in SMPS?

[satya_vijayawada]

Hai
How to measure the INRUSH current in SMPS. And how to limit the inrush current.

 

[VVV]

Re: Inrush current

You can use a current probe in series with one of the input leads. Normally, the voltage is applied from a controlled power source, so as to adjust the phase angle. Measure the peak current using this setup.

To limit the inrush current, you can use thermistors in series with one of the input leads (check out the AVX website, they make inrush-limiting thermistors) for low-power SMPS (up to about 50W).
For higher power you can use a series resistor, but short it out with a triac shortly after power up, in order to avoid dissipation.