How to choose a switching power supply that does not fail [I will explain in an easy-to-understand manner]

You should also choose a noise filter as a set with a switching power supply.

Next, I will explain the basics of noise.

What is noise?

Our lives are surrounded by electronic devices. These devices and devices always generate electrical noise. I think I’ve experienced noise and image distortion on the radio and TV. That’s fine, but it’s a big deal if the factory’s industrial equipment malfunctions, medical equipment (such as a pacemaker) stops, or the station radio is noisy.

Noise is divided into “conduction noise” and “radiation noise” according to its transmission path.

Conduction noise is noise transmitted from patterns on cables and printed circuit boards. Radiated noise is noise transmitted from the air.

It can be said that devices that operate on AC power are connected by a common power line called AC. Noise generated by other devices may be transmitted to the AC line and cause malfunctions, and conversely, noise generated by your own device may cause other devices to malfunction.
The AC input section is also a noise inlet and outlet, so attach a noise filter there.

What is Conducted Emission?

Since the switching power supply is a semiconductor that switches (turns on and off) at high speed to step down the voltage, high-frequency noise is generated.

The noise that the high-frequency noise travels through the input wire and returns to the input line is called “noise terminal voltage”.
There are regulations on noise terminal voltage in each country. The contents are almost the same.

The noise filter is placed in front of the switching power supply and is used to attenuate the noise transmitted through the cable. In other words, the main purpose is to prevent the noise generated from the switching power supply from being returned to the AC line.

The radiation noise emitted from the switching power supply cannot be attenuated by the noise filter.
The noise is regulated in each country as “Radiated Emission“.

How to choose a noise filter

Noise filters have fewer electrical specifications than switching power supplies and can be easily selected.

Once the following basic specifications are determined, you can select a noise filter.

That is all for the contents. Thank you for reading.