Methods for protecting household electric networks from electrical surges, variety of protective devices and methods for their installation.

Constructive imperfection of electric networks is a major cause voltage surges. Predict the time of the next drop is not possible. The only thing we can do to prevent unpleasant consequences - is to take care of the safety of electrical consumers in their home.

To protect domestic consumers from power surges are subject to different types of protective devices. We will talk about the most common. This voltage control relays (RN) and domestic regulators.

Relays of voltage control

Protect the home power supply system using the PH is recommended in cases where the voltage is stable, and its noticeable jumps are rare. The relay control voltage is a device capable of reading parameters of the electric current, and to break the electrical circuit in a time when the voltage indicators will go beyond the set range. Once the voltage on the public network is normalized, the device automatically closes the circuit and resumes power consumers. refeeding function after a specified period of time (with a delay), built-in pH and helps extend the life of some home appliances, such as refrigerators.

monitoring relays have a small size, relatively low cost and good performance. The disadvantages of PH include their inability to smooth out voltage fluctuations. In addition, for maximum protection of all consumers need to install multiple devices.

RN only protects the network against harmful voltage spikes and is not intended for protection against short circuits (this function is performed by circuit breakers).

Modern RN are of three types:

1. Stationary relay embedded in the switch box home or apartment.

2. Relay for individual protection of the consumer.

3. Personal protective relays several consumers.

If the operation of the relay of the second and the third type is almost all clear, then the pH of the first type has a more complex configuration and its installation requires some knowledge. Such devices are mounted at the entrance to the room and protect against voltage surges all domestic electrical equipment.

Selecting the PH

Choosing voltage relay to protect your home network, it is sufficient to know the face value of the electric current, which is able to pass through a lead-in circuit breaker. If, for example, the bandwidth switch is 25A (corresponding to the power consumption - 5.5 kW), the performance of the RN must be a step up - 32A (7 kW). If the switch is designed to 32A, the relay must withstand current 40 - 50A.

loa (pozovatel FORUMHOUSE)

I took the occasion to relay 40 A at an introductory machine 25/32 (there is a first, but may increase the setpoint).

Some people choose a brand RN, based on the total power consumption. This is not entirely correct. After the relay, capable of withstanding the current in 32A, can easily work as a load of 7 kW, and at a much higher power consumption. Only in the second case in a working circuit RN is necessary to incorporate a special magnetic contactor. But more about that in the next section.

Installing RN

The standard voltage setting circuit relay in a junction box shown in the diagram.

Works on installation of PH should be performed only when the main switch is turned off!

As you can see, everything is simple: monitoring relay is set immediately after the electric meter and connected to the phase conductor through which the power supply of the house. When voltage jump beyond the exposed (adjustable) range switch disconnects the external supply network of interior wiring.

RN, is mounted in the plate, it takes a minimum of space on the DIN-rail.

If the total power of the consumers home network of more than 7 kW, manufacturers are strongly recommended to build into a working circuit PH additional magnetic contactor. Although reliable contactor in the general scheme will never be superfluous details.

Vitichek (user FORUMHOUSE)

To anyone better to put the relay contactor, even though producers and write that RN withstand high currents. The contactor has great contacts and lower resistance.

This device helps to relieve contacts RN independently disconnecting a power line from a common network of residential customers. Relay control, at the time of an unacceptable power surges, only a command to shutdown. After that, the electromagnetic coil of the contactor disconnects the power terminals, connect the internal and external network. The circuit connection in this case will be as follows:

Adjusting the voltage control relays

In order to stress the relay could benefit its owner, its operating parameters (Allowable stress limits and supply resumption time delay) must be properly adjust. If the operating voltage circuit uses one relay, then set limits on the permissible values ​​should be, focusing on the characteristics of household appliances and sensitive to changes. The most sensitive and expensive equipment is the audio-visual equipment. The range of allowable tension values ​​for it is 200 - 230V.

The permissible deviation from the nominal voltage performance in domestic power networks of 10% (198... 242V). Frequent tripping RN, these figures can be taken as a basis, carrying out a relay control. However, sensitive consumer electronics, it is recommended in this case to protect using inexpensive portable stabilizers.

DenBak (user FORUMHOUSE)

Nobody says that it is necessary at plus or minus 15V off. There are a range of maximum permissible deviation of 10%, the majority of its equipment must withstand. Need to put on this basis, approximately 190V-250V. Although, with our state of the networks, particularly in the private sector, everything is possible. So reasonable caution not hurt.

In order to ensure maximum protection for all consumers, should use an electric circuit with several relays. Working protection scheme involving several pH, allows you to split into groups of consumers - according to their sensitivity to voltage surges:

• The first group includes audio and visual equipment (allowable voltage value - 200 - 230).
• The second include household appliances equipped with an electric motor: refrigerators, air conditioners, washing machines, etc... (Allowable voltage value - 190 - 235V).
• Third group - this heating appliances and lighting (allowable voltage value - 170 - 250V).

Each group of consumers connected to its pH. In this scheme, the operating parameters of each relay can be individually adjusted.

As for the time delay the resumption of power, it must meet the performance requirements for household appliances. For some refrigerators, for example, the recommended delay is 10 minutes.

Protection of three-phase systems with a pH

If the power supply of your home through a three-phase system, for each phase it is advisable to install a separate control relay.

Three-phase voltage relay is designed solely to protect the relevant equipment (eg, motor). If such a switch is mounted in the housing on the input, the bias voltage on one of the phases leads to a blackout of all single-phase consumers.

Surge Protectors

If in your house there are constant power surges, the rocket will fire several times a day, de-energizing the whole house. In such cases, more expensive, but also more practical way to protect your home electronics. It consists in the use of stabilizers - devices smoothing surges in the external network, giving a constant rate at the output 220.

According to the type of connection stabilizers are two types: local (which is connected to the outlet, protecting from one to several consumers) and fixed (connected to the input power cable and carrying out protection of all consumers home network). Local regulators must be used to protect the most sensitive appliances. They can be operated together with a fixed voltage relay. Regarding stationary stabilizers, they are complex devices that are not only smooth variations the voltage across the home network, but also can automatically turn off the power of consumers at critical values.

Install stationary stabilizer is highly recommended, if the voltage is several times a day beyond the 205... 235V (which can be determined by using an ordinary tester).

If you are constantly blinking light in the house, and the voltage is outside the 195... 245V, then use the household electrical appliances is prohibited without stabilizer!

How to choose the stabilizer

Choose the stabilizer should be based on the total power of domestic consumers. The device must necessarily possess decent power headroom.

Mishael761 (user FORUMHOUSE)

Power margin should be 2 times larger than the current requirements. That is, the stabilizer 10 kW designed for half the actual load (5kW) with minimum external voltage - 150 volts (i.e., when a large drop). This should be considered when choosing.

Installing the stabilizer

Set stabilizer is recommended near the power panel in accordance with the following scheme.

Embed stabilizer (however, as RN) in the general scheme follows immediately after the meter. After all, these devices are also consumers, therefore, before the registration of the device can not be installed.

Protection of three-phase networks with stabilizer

Just say that the three-phase stabilizers are intended to protect only three-phase consumers. If your home is suitable three-phase power, then to create a stable voltage on the internal network it is advisable to install on each phase of a separate single-phase stabilizer.

Such an approach will significantly reduce your costs (3 stabilizer power of 5, 7 and 10 kW always one less device capable of 30 kW). In addition, during voltage dips on one phase, three-phase unit will de-energize the entire house. This design feature of the stabilizer, based on the protection of three-phase motors.

discuss features selection and operation of stationary stabilizer You can visit the appropriate section of our forum. If you are interested to share experiences setting voltage monitoring relays in a pair with a contactorThen in this case we also find a suitable topic. A video detailing the mounting panel and junction boxIt will help you to connect the apartment to the power supply system in accordance with the generally accepted rules of electrical work.