The reason for the breakdown of household appliances and electrical household appliances is voltage surges (PN). This is due to the fact that each electrical unit can run smoothly and efficiently only with certain parameters of electricity, in particular - the voltage in the network and its strength. If these standards are exceeded or decreased, an emergency will inevitably occur. In order to minimize or eliminate the risks of large financial losses, care must be taken to protect against overvoltage of the 220V network.
What are voltage drops
In accordance with the definition that is given in GOST, voltage drops or overvoltage is a sudden short-term decrease or increase in the amplitude of the voltage with subsequent restoration to nominal parameters.
The nature of the origin of this phenomenon is explained by the fact that several decades ago, designers and builders could not even imagine that in modern times, so many electrical equipment will be concentrated in each apartment. The maximum electricity consumption in the morning and in the evening negatively affects the operation of the entire electricity network.
The electricity that flows through the cable is simply unable to withstand such loads, which contributes to their abnormal overheating. Over time, this leads to a weakening of the contacts in the distribution panel. Also, the neutral wires often burn out, which can cause a voltage surge, for example, from 110 to 360 volts.
Switching overvoltage
When there is a moment of voltage drop in the electric mains, their amplitude changes over a short period of time. After that, they quickly return to the parameters that were at the beginning.
The duration of such an impulse does not exceed several milliseconds, its formation can be due to one or several reasons:
- When connecting powerful electrical equipment, for example, electric welding, a collector motor, the phenomenon of electrostatic induction is observed.
- Overvoltage caused by switched processes. They, in turn, are observed at the time of disconnection or inclusion of high-power electrical appliances.
- Lightning discharges. This natural phenomenon can cause power surges up to several kilovolts. No device is able to withstand such changes in the network, and thunderstorms often become the causes of fires and network outages.
The insulation material of most wires is designed for significant PN, so breakdowns rarely occur. If nevertheless this happened, an electric arc arises. As a result, a free path appears for the electron flow.
The role of conductors are gases that fill all the formed voids. Over time, if the breakdown is not eliminated, the current gradually increases, and protective automation does not detect an emergency in a timely manner. This leads to the failure of almost all the wiring in the room.
Long overvoltage and voltage dips
Most often, a provoking factor of prolonged overvoltage in networks is a violation of the integrity of the neutral wire. This condition is accompanied by an uneven distribution of the load on the phase conductors, which leads to phase imbalance.
An uneven three-phase current acts on a zero ungrounded cable, which contributes to the accumulation of excess voltage in it.The process of increasing its concentration will continue until the malfunction is resolved or the network finally fails.
Another dangerous condition of the electrical network that can cause significant damage is a lack of voltage or a failure. Such phenomena are quite common in rural areas. The bottom line is a drop in the indicator to critical levels, which poses a serious danger to wiring, household appliances and all electrical appliances. Many modern household appliances are equipped with several power supplies, a voltage dip leads to the shutdown of one of them. This stops the workflow of the technique. Eliminate the problem and prevent it in the future will help the stabilizer, which fixes the critical marks and regulates the voltage to rated values.
Types and principles of protection devices
Overvoltage protection can be carried out in various ways. The following devices are considered the most popular, simple to implement and reliable:
- lightning protection system;
- voltage limiters (stabilizers);
- overvoltage sensors that are used in conjunction with an RCD, in case of emergency or emergency situations, cause current leakage;
- overvoltage relay.
Uninterruptible power supplies that perform similar functions have also been developed. The specifics of their work is to continue to work and turn off the device in accordance with all the rules.
Lightning protection
Depending on the construction project and technical conditions, lightning protection systems can be arranged in different ways.
- A common way is the organization of external lightning protection. The power of a lightning strike will fall directly on the elements of the system itself. The approximate current is 100 kA. It is possible to protect oneself from a powerful pulse with the help of a combined SPD, which acts as a switch and is mounted in a water electric distribution panel. One such protection system will prevent the failure of all equipment in the house.
- There is no external lightning protection, voltage is supplied to the house via an overhead line. During a thunderstorm, lightning strikes a transmission line support with a rated current that passes through an SPD, the value is approximately the same as in the previous version - 100 kA. Special protective devices will help protect household appliances from a powerful power surge, which are installed on the input shield, the branch line, on a post or wall of the building. During operation of the switchboard, protection occurs according to a scheme similar to the previous method.
If the SPD is mounted on a pole, it is not practical to use differential devices, since voltage spikes are still possible at a distance from the house to the pole.
Surge arresters
Surge protection issues should be regulated by service providers. They must install the required protective structures on the power lines. However, in practice, the problem of protecting the house from power surges is the problem of its residents.
Protection against power surges in the network at overhead power lines and substations is carried out using surge arresters - non-linear surge arresters. The structure includes a varistor. Nonlinearity consists in changing the resistance value in accordance with the value of the applied voltage.
When the electric power network operates in the normal mode, and the voltage corresponds to the rated one, the limiter has a large resistance, which does not allow current to flow. If, for example, an impulse is formed during an electric shock, a sharp decrease in resistance is observed, which leads to a voltage surge.
There are compact blocks of modular surge protection that take up little space in the distribution box at home. These devices are connected to a grounding circuit or working ground, through which dangerous impulses pass.
Surge Protectors
The stabilizers normalize the voltage and bring it in line with the rating. Using the integrated toolbar, the permissible limits can be adjusted from 110 to 250 volts.
If the voltage starts to jump in the network, the device captures and turns off the power in automatic mode. The power supply resumes only after the network indicators return to operating mode.
Network filters
Electrical designs have significant advantages compared to peers - affordable cost and simple design. Despite the low power, the filter is able to protect household appliances with power surges up to 450 volts. As practice shows, even if the manufacturer claims great performance, the surge protector does not stand above 450 volts - it burns out, but at the same time leaves expensive household appliances intact.
A varistor plays a key role in overvoltage protection. When indicators above 450 volts are reached, it is he who burns. The part reliably protects electrical structures from high frequency interference that may occur when turning on or off electric motors or welding machines. Another important design detail is the fuse, which trips on short circuits.
If you compare between the voltage regulator and the power strip, it is better to give preference to the first, especially when living outside the city or in the countryside.
Before proceeding with the installation of protection against voltage surges 380 and 220 volts, you need to make sure that the network is completely de-energized. The circuit breaker cuts off the electricity supply and checks the voltage at the output using an indicator screwdriver. Also of great importance is the quality of the materials used. Flammable must be discarded, because sooner or later they will inevitably lead to an accident.
