Why do I need a network filter?

One of the criteria for the normal operation of electronic devices is stable power. Changing the voltage in the supply network can be critical for the operation of a household or other appliance. Semiconductor elements provide additional opportunities for developers of various devices. Unfortunately, they are sensitive to operating conditions and require a careful attitude. One of the devices that can protect electronics from damage during voltage drops or high level of impulse noise in the power supply network is a mains filter. He perfectly copes with his task and extends the service life of devices.

Let's imagine the supply voltage in mind and consider how different types of consumers affect its parameters. And how does the network filter save the electronic device from damage? Ideally, the supply voltage is a sinusoid. It is constant in its current (amplitude) value and frequency. Unfortunately, when switching on of powerful consumers of electric power, there are various kinds of interference that can damage sensitive devices.

In the home, such "noisy" electrical appliances include vacuum cleaners, refrigerators or air conditioners. That is, where asynchronous or other types of motors operate, distortions in the power supply network will necessarily arise. This is due to arcing on brushes or for some other reason. Even the work of an ordinary electric shaver can disrupt the work, for example, of radio receivers. In other words, under the condition of working with an inductive load and with a short break in the electrical circuit (as in the case of brushes in an electric motor), interference is introduced into the mains. They are short-term pulses of increased voltage. A network filter, strictly speaking, was created to deal with such anomalies.

But the problem is not only in electric motors. One more kind of strongly "noisy" devices are the modern electronic devices themselves: televisions, tape recorders, computers, etc. It turns out that the mains filter is able to protect electronics from damage, which itself creates unfavorable conditions for its operation. The fact is that modern devices have in their composition impulse power supplies, whose operation is associated with a frequency of 1000 and more Hertz. Since at the input of such devices there are transformers having a certain inductance, interference occurs.

They are easy to see with an oscilloscope. You can assemble a small power filter yourself, to be sure of the effectiveness of its application. To do this, it is sufficient to create an inductance, which will prevent the passage of high-frequency interference in the supply network. To do this, simply wind a certain number of turns of the wire, for example, brand SEV on the ferrite ring and solder it consistently into the supply circuit for your computer. With the increase in inductance (the number of turns) you can see on the oscilloscope that the noise gradually disappears.

Currently, there is a large number of network filters, which are designed specifically to work with different types of load. A good example in this case can be the Pilot network filter, which has excellent performance characteristics.