Thanks to technological progress, almost all real estate objects where a person is present are connected to electricity. Electricity is used for lighting, powering devices and household appliances necessary for normal life. Unfortunately, end-users face technical problems in the operation of power grids, including voltage drops and phase imbalances. To secure household appliances use a voltage relay.
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Voltage relay - what is it and what is it for
The rated supply voltage of the equipment is 220 V.But it is impossible to provide ideal conditions for the transmission of electricity, so consumers constantly observe surges in the network. Especially often the problem is faced by residents of apartments in old multi-storey buildings and the private sector.
Important: normal is a deviation from the nominal value within 10%.
Voltage control relay (RKN) is a technical device designed for continuous monitoring of network parameters and automatic power off in case of sudden power surges. The device is triggered if the indicators go beyond the set values.
In other words, the device protects electrical appliances from voltage surges in the network, which could occur due to the short circuit of one of the phases, zero break, phase imbalance, etc. It should be noted that the equipment is negatively affected by both excessive and insufficient supply voltage.
The device and principle of operation of the voltage relay
The voltage relay consists of two main parts - a measuring unit and an electromagnetic relay designed to break the circuit. Newer models have a digital display on the front panel to indicate the magnitude of the voltage in the network.
The principle of operation of the voltage relay is quite simple. When voltage is applied, the measuring unit determines its value and compares it with the set limits. If the indicator is between the lower and upper limits, after the set period, the relay closes the power contact and transfers power to the internal network.
Reference: the relay has a response delay interval to protect the network from constant surges.
Main technical characteristics
Most relays operate at voltages between 50 and 400 watts.Such a large interval allows the device to be used both in single-phase and three-phase networks, as well as to flexibly adjust the desired limits for the operation of the protective device. Of the main technical characteristics should be highlighted:
- supply voltage;
- maximum load power;
- maximum load current;
- degree of protection on the case;
- switching resistance of relay contacts;
- load off time;
- maximum cross section of connected wires;
- turn-on delay time;
- overall parameters.
Classification and types
To protect the electrical network of a private house, an apartment in an old and new housing stock, different devices are needed. Voltage relays are divided into two categories:
- by type of connection;
- by the number of phases.
By connection type
There are two main categories of voltage relays depending on how they are connected:
- stationary;
- portable.
Stationary control devices are divided into two types. Devices for installation in electrical panels and built-in sockets. Let's take a closer look at each type.
The voltage relay installed in the switchboard has a number of advantages. The device is mounted at the input of the network to protect all electrical equipment of a house or apartment. If it is used, there is no need to use additional relays to protect individual consumers, which significantly saves the budget.
Voltage relays represent an excellent alternative when it is not physically possible to install the device in shield. Use sockets for point protection of appliances such as refrigerators, boilers, washing machines, etc.
Advice: to save your budget, choose double sockets!
Portable relays are represented by two types - a plug-socket and an extension cord. They are used when the installation of a protective device at the mains input is not possible. Despite the bulky parameters, portable devices are in demand. This is primarily due to their portability and ease of use (installation is not required).
Plug-socket designed to protect only one consumer. The device plugs into a standard outlet and monitors node voltage fluctuations without monitoring the overall network condition. Suitable for protecting expensive and powerful electrical appliances.
Extension with a built-in control relay is used to protect a group of devices from network surges. A convenient and simple solution has only one main limitation - the maximum load power.
By number of phases
Depending on the type of power supply, two types of relays are distinguished:
- single-phase;
- three-phase.
The single-phase relay is designed to control electrical networks with an operating voltage of 220 V. When properly configured, the device is suitable for protecting almost all household electrical appliances.
Three-phase protective devices are used mainly in country houses and new housing stock, where a three-phase power supply connection is provided. And RKN controls the voltage of each phase.
Rules for choosing a voltage relay for an apartment or house
It is necessary to approach the choice of ILV wisely, because the device is responsible for the security of the network and electrical appliances. Correct operation of the relay is possible only if the technical characteristics are correctly selected.When choosing a voltage relay, consider:
- maximum load current and type of connection by phase;
- maximum power of the consumer;
- operating voltage range;
- protection response time;
- control type (digital and electromechanical);
- degree of protection of the device;
- reliability (manufacturer and model reviews).
The main parameter when choosing a device is the maximum allowable current. You should choose a model one level of protection higher than the installed machine in the switchboard. If the maximum current of the switch is 32 A, then the relay must be 40 A.
Advice: it is worth paying attention to additional functions, such as digital indication of voltage, temperature of the device, the ability to control time, etc.
Wiring diagrams
There are two main ways to connect the ILV - direct, when the workload passes through the ILV contracts, and also indirect - the load is switched through contactor. The second method is needed when connecting a load above 7 kW. Connection recommendations:
- the relay should be mounted after the electricity meter;
- install a means of protection in front of the ILV (input machine);
- accessibility of the device for maintenance and visual control of work.
Connection of a single-phase ILV
Single-phase ILVs are connected to the network directly, and the operating current of the network passes through their contacts. As a rule, before the relay is installed RCD or difavtomat for leakage protection. The connection algorithm is as follows:
- Zero from the input machine is connected to the zero bus, and then to the output N on the relay.
- The phase wire is directly connected to terminal L.
- The third output of the ILV is designed to connect the load, the ground and zero for which is taken from the tires.
Connection of a three-phase ILV
For direct connection of a three-phase ILV, it is necessary:
- Connect the phase wires of the three-pole input machine.
- Install the ILV by connecting the phases and zero to the appropriate terminals.
- Attach phases and zero to the pins RCD.
- Turn on the load by connecting the ground and phases, as well as zero from the N-bus installed after RCD.
RKN connection diagram for powerful consumers with a contactor
When the switched currents are significantly higher than the maximum permissible value of the ILV, the device is used in conjunction with a magnetic starter (contactor). When choosing devices, you should pay attention to speed - the lower the response speed of both devices, the better.
Advice: it is cheaper to buy a contactor and a voltage relay than to choose an ILV for powerful consumers.
The scheme differs from the usual connection in that a contactor is installed after the circuit breaker, which switches the load. The relay is connected in parallel with the starter and only controls the voltage value. With significant deviations, the ILV is triggered, de-energizing the contactor coil, which leads to load disconnection.
Setting operating modes
Regardless of the type of relay, there are three main parameters for setting:
- Upper voltage limit Umax - is responsible for the maximum allowable value in the network, the excess of which will lead to a power outage.
- Lower voltage limit Umin - is responsible for the minimum allowable value in the network. If the reading falls below the set value, the load will be disconnected.
- Turn-on delay time - time to re-apply power after a power outage.The device turns on only if the voltage is within the set values. Typically, the delay time is set in seconds.
Advice: if there is an air conditioner or a refrigerator in the room, the delay time should be more than 300 seconds.
To change the parameters, use the mechanical or digital buttons located on the front of the device. How to change the device settings correctly is described in the instruction manual.
How to test a voltage relay
All devices are tested in the quality control department before reaching the end user. If you doubt the serviceability of the ILV, you can check it in the following ways:
- measure voltage multimeter or a voltmeter between the phase and zero terminals. The value must correspond to the indication on the digital display. Take into account the error of the multimeter.
- Invite a specialist with a verified measuring device to get the most accurate result.
Every year more and more expensive electrical appliances appear in homes. To ensure their correct operation and save the wallet from expensive repairs, it is necessary to use a voltage relay. If it is not possible to install ILV at the input of the network, use portable devices.
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