How to protect the network from overvoltage and what is needed for this

The main causes

Most often, overvoltage in the 220 and 380 Volt network occurs for the following reasons:

1. Neutral wire break on the supply line. The zero conductor provides voltage symmetry in the phases of the supply network, at different magnitudes of the load in phases. In the event of a zero break, the voltage in each phase varies depending on the difference in phase loads: in a less loaded phase it increases sharply up to 300 volts and more, and in a more loaded phase it drops sharply to below 200 V. Therefore, without overvoltage protection at high voltage household appliances can fail almost immediately, but if low voltage electrical appliances will not work correctly. At the same time, there is a high probability of failure of electrical appliances, the design of which has electric motors (compressors).
2. Error connecting in the electrical panel. If a three-phase input is made in the house and when connecting a single-phase wiring line of 220 V, the second phase conductor was incorrectly connected instead of zero, then 380 V will appear in the outlet instead of 220 V.
3. An impulse voltage occurred due to a thunderstorm entering a power line (which is why it is recommended to turn off all household appliances during a thunderstorm, as well as do lightning protection in the area).
4. Switching overvoltage. In case of emergencies in the electric network: short circuit on adjacent lines, abrupt change in load due to disconnection (connection) of a section of the electric network, accidents at power plants, can be observed voltage drops, which, depending on the size, can adversely affect the operation of home electrical appliances.

As you can see, on overload in a single-phase and three-phase network affects many factors, including natural ones. Therefore, home wiring must be protected so as not to become a victim of an accident.

Surge Protector

In the modern world, there are many different devices for surge protection in the network, which are easy to connect with your own hands. Consider devices that are used to protect against unwanted power surges.

Among the most useful for use in the house and apartment are:

1. Stabilizer. This device converts (stabilizes) the input voltage into a voltage of a given value. It is important to install the stabilizer in the event that constant voltage drops are observed in the network. It should be borne in mind that the stabilizer only works at a voltage that does not exceed the permissible values ​​that are indicated in its technical characteristics. In the event of voltage surges above acceptable limits, the stabilizer may fail. Therefore necessary choose a voltage regulator with built-in surge protection, and in the absence of such a function, install a voltage relay to protect. About, how to connect a voltage regulator, we told in the corresponding article!
2. Voltage relay. This protective device, unlike MV, does not convert the input voltage. Voltage relay It is designed to disconnect home wiring from the electrical network in the event of undesirable voltage drops (GOST 3699-82). The limits of the minimum and maximum voltage are set on the relay, and in the event of a jump above the set limits, the relay de-energizes the home wiring, thereby protecting home appliances. The LV can be made in the form of a modular apparatus for installation in a distribution panel (the well-known Barrier), built into an extension cord (surge protector with the corresponding function), and also in the form of an electric plug (for example, ZUBR). About, how to choose a voltage relay We talked in a separate article.
3. Multifunction protection device (UMM). This device can be installed in a switchboard instead of a voltage relay. UZM performs several functions, one of which is the protection of the electric network from voltage surges. About, how UZM-51M works and how to connect it, we told in a separate article.
   
4. Uninterruptable power source. Again, from my own experience I will confirm its effectiveness. More than ten times, the UPS saved my computer from a sudden shutdown when the voltage relay in the electrical panel tripped. “Uninterruptible” has a low cost, so it is extremely necessary to buy such an option for surge protection in the presence of a PC. In addition, most modern uninterruptible power supplies have a built-in stabilizer, which is especially important for computer equipment, which is more likely to be affected by fluctuations from most household appliances. Read how to choose a UPS in our article: https://our.electricianexp.com/en/sovety-po-vyboru-besperebojnika.html.
   
5. SPD. From impulse voltages (occur during a thunderstorm and can disable equipment), you can protect yourself by installing an SPD in the house. This device is quite popular today and is widely used both in everyday life and in production. More about what is SPD and how it works, we described in a separate article, which we strongly recommend that you familiarize yourself with. It should be noted that SPDs can also be called modular surge arresters (OPN).
6. Contacting the power supply service. The energy supplying organization, in accordance with the electricity supply agreement, is obliged to provide a normal (within the acceptable limits) voltage level of the electric network in accordance with GOST 29322-2014 (IEC 60038: 2009). Therefore, if you have constantly excessively low or, on the contrary, increased voltage, then you need to contact the supplying organization with a corresponding complaint. It is most effective to handle a collective complaint, as single appeals are usually ignored. Contacting the supplying organization is the only way to solve the problem if you experience severe voltage drops, since in this mode any MV will quickly fail.

Finally, we recommend watching a useful video on the topic of the article:

After installing the necessary devices, overvoltage protection in the 220 and 380 Volt network can be provided, after which you can not worry about the fact that household appliances, electrical wiring and most importantly, your life will be in a dangerous situation.

Recommended reading:

• How to connect the difavtomat correctly
• The reasons for the operation of the RCD
• What is better to put: difavtomat or RCD