The relay is a device capable of operating in automatic mode. Today on sale you can find a classic intermediate relay of 220 V electromagnetic type, as well as modern electronic devices. These devices are widely used in industry and everyday life. They are actively used for switching electrical circuits, controlling electric motors, and so on.
Content
- Scope and purpose
- Design features and principle of operation
- Technical parameters and decoding of marking
- Classification methods
Scope and purpose
It is difficult to find an industry where intermediate relays are not used. These devices are now installed in various electrical equipment and household appliances. There are three cases of using these devices. in complex electrical systems:
- Switching sections in power grids independent from each other.
- Increase in the delay time of the operation of protective elements in circuits with high load currents.
- Monitoring of various parameters, as well as the modes of operation of individual elements in secondary electrical circuits with high voltage.
It should be noted that one device is capable of performing sequentially or simultaneously several switching in circuits. As an example, consider the operation of a relay in a water supply and heating system. When the pumping station is turned on, a supply voltage is applied to the winding of the device. As a result, the contact group closes, activating the pump operation control system.
The display shows the most important parameters of the installation. Their number depends on the complexity of the controlled system. At the same time, another contact group closes, thereby supplying voltage to the winding of the magnetic starter.
When this starter is triggered, the supply voltage is applied to the electric pump. Since in heating systems a weak impulse does not allow the activation of the magnetic coils starters designed for high current, then with the help of an intermediate type relay it is possible to increase control signal.
Design features and principle of operation
The design of the device resembles a small magnetic starter. It should be noted that the relay cannot be used in all circuits for switching electrical circuits, since its main purpose is to transmit control pulses. This is because the contact plates are made of thin material. On sale, there are rarely models that can pass currents of more than 10 A.
The design of the classic relay of the intermediate type contains:
- The base on which all other parts are mounted.
- Electromagnetic coil and core.
- A movable plate equipped with a lever for controlling the contact group.
- A spring to return the lever to its original state when the tension is removed.
- Contact group.
- Terminals for connecting conductors to contacts and coil winding.
Technical parameters and decoding of marking
An experienced electrician will be able to extract almost all the information you need from the product labeling. As an example of decoding, we can take the REP26-004A526042-40UHL4 model. This is an electromagnetic intermediate relay, 26 series. The device is equipped with 4 changeover contacts with endurance class "A".
The relay is designed to work in DC circuits. The conductors are soldered in, and the design also includes a manual switch. The protection class of the product against moisture and dust ingress is 40. The relay is designed to operate in mid and northern latitudes.
As for the most important technical characteristics of the device, then the following are worth noting:
- Minimum switching current.
- Voltage range on the electromagnet winding.
- Contact group opening time.
- Switching voltage indicator.
- The maximum permissible power of the load connected to the product.
- An indicator of the permissible short-term current passing through the contacts.
Classification methods
Intermediate relays are usually divided into groups according to different parameters. However, only the main types of devices should be considered. According to the type of switching, the devices can be minimum and maximum. They are designed to decrease or increase a certain parameter to the desired value, respectively.
Depending on the functional purpose it is customary to distinguish three types of relays:
-
Combined - a group of devices is combined to solve a specific logical task. - Logic - operate with similar parameters in discrete electrical circuits.
- Measuring - designed to change certain indicators in a given range of values.
The next type of device classification is determined by the way the load is controlled. Direct action involves connecting the relay contacts directly to the load. An indirect effect is also possible when the load is connected through the electrical circuits of the secondary elements.
According to design features the following types of relays are distinguished:
- Semiconductor - switching is done not using mechanical contacts, but due to the supply control pulse on p - n - p and n - p - n junctions of semiconductor elements, for example, thyristors.
- Inductive - the control signal is a voltage induced in an adjacent winding that is not directly electrically connected.
- Magnetoelectric - the magnet in the design of the device is a fixed element, and the winding with the contact group rotates, closing or opening the circuit at the same time.
- Polarizing - switching the desired contacts is determined by the polarity of the connection on the winding.
Thanks to the use of relays in everyday life, you can automate the operation of various systems. For example, these devices can be used to control lighting or heating. It will be easy even for a novice home master to connect the device.
