Relay connection diagram: device, application, subtleties of selection and connection rules

Voltage instability in the electrical network leads to breakdowns of household appliances.If you can prove someone else’s guilt in such damage to property, you will receive compensation. But, you see, it is much easier to prevent such a situation than to go to the courts and experts.

We will tell you how to avoid power surges - why this happens, what devices to use and what a working diagram for connecting a voltage relay looks like.

Why do power surges occur?

Various devices operating from the mains have limitations on voltage parameters. This even applies to incandescent lamps, although in order to cause them to burn out, a significant excess of the specified standards is required.

Reduced mains voltage, affecting, for example, a refrigerator, threatens an interturn short circuit and breakdown of the compressor. The increase negatively affects both the compressor and the electronic elements of the device, as a result they fail, and repairs cost a lot of money.

Again, even a wide range of voltage parameters does not mean that the device will operate during surges, for example, from 100 to 240 volts. This means its viability in a given period, subject to the stability of the power grid.

Generating electrical installations are designed with an automatic voltage stabilizer. In this case, the deviation from the norm, according to GOST 721 And GOST 21128, should not be more than 10% for a short-term network fault and more than 5% for a long-term one.

However, at least 7 main reasons of a natural, emergency, or man-made nature can provoke them:

1. Worn out electrical wiring in the house.
2. Lack of stabilizers at the transformer substation.
3. Overload of power consumption on the line.
4. Emergency situation in transmission networks.
5. Break on the neutral line.
6. Bypassing metering devices by unscrupulous consumers.
7. Natural factors.

The consumer is responsible for the operation of electrical appliances, proper distribution of the load on internal wiring and the condition of these networks. If a malfunction or emergency is detected, you must immediately call the special service.

You can measure the voltage using a special device, a multimeter (tester). If a deviation from the norm is detected higher than 10%, it is recommended to immediately contact the emergency service of the local power grid to identify the causes of power surges

System power grids are entirely the responsibility of electricity suppliers. One of their tasks is to monitor voltage deviations from the norm in a fixed area.

But despite the delineation of responsibilities, even with strict control, differences are quite common.

By identifying the culprit of power surges on the line, you can achieve justice and full compensation for damaged property or poor quality of services provided.

Is it possible to stabilize the voltage yourself?

Even if you are sure that justice will prevail and the perpetrators will compensate for the damage, accidents of this nature can lead to stalemate consequences, and legal red tape is far from the most pleasant experience.

In order to prevent the consequences of voltage deviations from the norm, you can purchase and install special devices - voltage control relays and/or stabilizer.

To equalize the optimal voltage parameters in the network, stabilizers are usually used - local or stationary. But this is not always a good choice due to the fact that the devices do not operate promptly and too much time may pass before the parameters are brought to the nominal value. This option is usually not suitable for surge-sensitive electronic equipment.

Control relay - one of the most budget-friendly, reliable and easy-to-use options. With its help it will not be possible to stabilize the voltage, but the equipment will be under reliable protection.

Working principle of a voltage relay

It is recommended to purchase and install the device in cases where power surges do not occur too often.

The device, using a microcontroller, records the parameters of the electric current and if the values ​​exceed or decrease beyond the range specified by the operator, it will open the electrical network. When the relay detects stable parameters on the line, it will automatically resume power supply.

A voltage relay may look different and also have a different set of functions. Some devices can even be controlled remotely via a contactor

Also, on many relay models, the off/on delay time is set. A timer is necessary to control short-term voltage surges, for example, it will not open the circuit immediately when it leaves the range, but if deviations are observed for 5-10 seconds.

As for the power-on delay, manufacturers indicate the time for their devices that must be waited to restart again in order to prevent them from burning out.

The relay has its drawbacks; it cannot smooth out fluctuations, but in combination with this device, voltage stabilizers can be used.

It has many more advantages than disadvantages:

• savings on purchase (lower cost than other protective devices);
• reliability in use;
• visual control of voltage parameters via a digital display;
• fast reaction.

The device is easy to use and operate. Selecting and installing it is also not difficult.

How to choose a voltage relay?

The relay is available in 4 types - a DIN-rail module (block), for protecting one consumer (plug-socket), for several devices (in the form of an extension cord with several sockets), a three-phase device (for equipment using 3 phases).

There is also an intermediate relay, it is designed to control independent electrical circuits, slow down the response of protection when high loads are required and to control devices that require significant voltage values.

The portable voltage relay is designed, depending on the model, for a current of 6 to 16 Amps. To connect consumers with large appetites, either several devices are installed or models are mounted on a DIN rail

When choosing the rated current, be guided either by the rating of the circuit breakers with DIN-rail relays, or by the power consumption of electrical appliances. In this case, you need to buy a device with a margin of 20-30%.

In addition, when choosing, take into account:

• operational efficiency;
• phasing (single-phase or three-phase devices);
• the ability to adjust the voltage range and operating limit;
• presence of a display;
• time control option;
• relay protection function against overheating.

As for which type of relay to choose, it depends on the amount of expensive and change-sensitive equipment.

If you choose a device on a DIN rail, you will protect all consumers, however, with a long-term surge, de-energizing the entire house is not always suitable for the owners, and in this case local relays are advisable.

Setting the voltage relay

Most often, the relay already has factory operating settings that are optimal for almost any case. But if you need to customize the device for yourself, this is quite possible, if the functionality allows it.

There is nothing complicated, basically there are only 3 functions:

1. Umax — option to set the maximum voltage value for relay activation. Most often they set from 210 to 270 Volts.
2. Umin — minimum threshold voltage. Typically 120 to 200 Volts.
3. Setting the timer switching after normalizing the parameters on the line. It is possible to set from 5 to 600 seconds.

Setting the desired parameters is carried out either digitally on the LED screen, or electromechanically using a variable resistor.

Pay attention to the factory settings, if you want to keep them, whether they are suitable for your operating conditions.

Some voltage relays do not have the ability to individually adjust the higher and lower thresholds. They usually cost less, but are less convenient to use.

If you are not satisfied with the standard setting for all electrical appliances, you can make a separate power line for them with additional RNA.Instructions for setting up devices are usually included with each device by the manufacturer.

Connection principle of the power control relay

If you have at least a little experience working with electricians, the connection will take no more than 20 minutes. At the same time, the set of tools is simple - figured and indicator screwdrivers, a stationery knife.

In general, the connection diagrams differ on different models, but manufacturers put them on the body or in the device passport. Therefore, having analyzed the general installation steps, you can easily cope with most types of devices.

A single-phase voltage control relay is usually installed between the IPU and a group of automatic machines. A phase and a zero approach the input of the device, but only the phase goes out to the load

Let's look at the simplest step-by-step instructions for connecting a single-phase voltage relay:

1. Disconnect electrical appliances from the power supply.
2. Make sure to de-energize the network using circuit breaker.
3. Using an indicator screwdriver, make sure that the area prepared for installation is not under voltage.
4. Install the RKN on a pre-fixed DIN rail according to the device manufacturer’s instructions, check the quality of the fastener.
5. Strip the wires going from the meter to the consumers.
6. Determine the input and output (often labeled on the device), connect the wires from the meter to the input and to the output to consumers.
7. Turn on the circuit breaker. Check using an indicator screwdriver to see if there is voltage at the relay input.
8. Activate the relay, set the voltage thresholds and delay timer.

Connecting a three-phase voltage control relay is more difficult. If you are not confident in your abilities and cannot carry out installation according to the diagram, invite a specialist.

Conclusions and useful video on the topic

Video #1. How to connect a voltage control relay yourself:

Video #2. How to install a three-phase voltage relay:

Video #3. 3 voltage control relay connection diagrams:

A voltage control relay will help keep electrical appliances in your home or apartment safe. This is, in fact, the simplest and most inexpensive way to eliminate the negative impact of power surges on the internal electrical network. Despite the different structure of the models, even a non-professional electrician can connect the device.

Have you ever installed a voltage control relay in your home? What difficulties have you encountered and what advice can you give to our readers? Share your experience and ask questions on the topic in the comments.