Installation relays

An installation relay is an electrical device that responds to a change in a certain physical quantity, such as electrical voltage or current. It performs a step change of state in one or more output circuits due to changing input conditions.

The task of the relay - controlling the electric circuit

The role of the relay is to control the operation of an electric circuit (or a group of circuits) in an efficient and safe way. Relays control lighting, ventilation systems, heating, heat pumps, but also quite small motors that drive shutters or blinds in the windows. Although the relays are implemented in various forms (e.g. for installation in boxes), today installation relays are the most popular - especially in applications in public utility facilities or residential buildings. It is worth knowing that regardless of the type of device, the appropriate selection of the relay is not only a key issue, but also requires some experience and knowledge in the field of electrical engineering.

Electromagnetic relay in installation housing

The installation relay is not some particular type of device, but simply an electromagnetic relay enclosed in a installation box . Thanks to this, it is possible to standardize the device dimensions and mount them on TH35 rail in modular switchboards.

The basic electromagnetic relay performs the on-off function, that is, it closes and opens the output electrical circuit with the use of a signal at the device input. The task is performed by two main elements of the device - the coil and contacts. After the control circuit is supplied with power to the coil, the contacts close or open - depending on whether they are make, break or changeover contacts.

Installation relays look very similar to miniature circuit breakers, i.e. esek. A diode is installed on their housing to indicate the status of the power supply. Most often, the correct power supply is indicated by a green LED emitting a continuous light.

Relays in building and industrial automation

Installation relays are commonly used in electrical installations of industrial automation. They are used in many production devices, electrical machines or control systems, e.g. conveyor belts. However, it is worth knowing that the relays are also responsible for controlling escalators in shopping centers, ventilation, elevators and street traffic lights. They are also very often used in building automation , where they cooperate with the control clocks of administrative circuits of multi-family buildings, switches in stairwells or other control buttons. They are also an important element of "smart home" systems.

How to choose the right relay?

An incorrectly selected relay will malfunction, which can easily lead to irreparable damage to electrical devices and electronic systems. Therefore, when replacing or installing the relay, the most important parameters of the device must be taken into account, such as:

1. type of contacts (make, break or changeover),
2. rated voltage - sometimes the manufacturer allows the device to be powered with both 24 V (alternating and direct) and 230 V alternating voltage,
3. maximum contact voltage,
4. maximum switching capacity, i.e. the maximum power that can be switched on with the relay,
5. load current (maximum and rated),
6. electric and mechanical durability determining the number of switchings for which the manufacturer guarantees the correct operation of the device,
7. operating temperature (usually manufacturers guarantee stable operation of the device at temperatures from -20 to 50 degrees Celsius).

It is also important to choose from the offer of proven, well-known manufacturers who guarantee that the relays made by them are of the highest quality, just like other devices.