Workflows of modern engineering equipment, electrical equipment and household appliances provide for extensive management capabilities. Moreover, the rate is increasingly being placed on the automation of control with minimal operator intervention. The means for implementing such functions may be different, but the relay forms the basis of the technical base. What it is? In a standard form, this device is with a winding, designed to close and open an electric circuit. According to this principle, control is carried out in the simplest systems, but the segment is developing and more and more complex devices of this type, focused on use in specific areas, are entering the market.
General relay device
The simplest design includes electromagnets, an anchor, as well as connecting fittings with conductors. When current flows to the magnets, the armature is reduced to the contacts, which leads to a short circuit in the circuit. To control the current strength and its conversion into mechanical stress, a spring is used. She communicates directly with the anchor, adjusting the degree of pressure on the contacts. In other words, depending on the characteristics of the current, the operating state of the apparatus changes, and with it the control of the target equipment. For example, the electromagnetic types of controller relays provide independent control of boiler plants, pumping units and other engineering systems, including or disabling their power components. For more accurate fixation of circuit signals, additional elements such as resistors are also provided. At the same time, capacitors can be used to minimize the risks of damage to sensitive devices due to power surges.
Appointment of the device
At a basic level, relays are used as a protective regulator when certain operating parameters of the system can adversely affect the state of the equipment. A classic example is the same electromagnetic regulators that perform a kind of electric filter function. When registering voltage or amperage of an abnormal value, they automatically close, thereby terminating the unsafe work process. That is, the protective function is basic and is provided in almost all types of this device. But in modern variations, other tasks appear, due to the need to increase the autonomy of management. If we consider the types of relays and their purpose from the point of view of the user, then in the list of tasks to be solved there will be the following:
- Assessment of fluid levels (in tanks, basins, flasks, etc.).
- Monitoring of operating parameters, including temperature and humidity.
- Providing data on energy consumption.
- Automation of equipment in accordance with the indicators of sensors.
The set of functions and the means of their execution vary depending on the conditions of use of the equipment and the purpose of the target system.
Main classifications
The main principle of separation of relay devices is based on the specifics of the field of use. The basic classification distinguishes thermal, level, electrical and automotive regulators. But each group also provides its own subcategories. The most extensive list of separation criteria in the segment of electrical switches. These include single and three phase relays, solid state structures, intermediate devices, etc. The types of relays also differ depending on the principle of operation. Mechanical devices are still retained, popular for their simple design, affordable price, and relatively high accuracy. In technologically advanced industries, mechanics are being replaced by programmable and digital relays provided by microcontrollers. The most vivid possibilities of such models are revealed in the time regulators - timers, through which the user sets the time intervals of the equipment.
Types of voltage relays
Such devices can be divided into household, office and industrial. Accordingly, they focus on servicing home electrical appliances, office equipment and production units (for example, processing machines and machine tools). In each case, protection against network fluctuations is provided. In particular, this is expressed in the filtering of voltage surges, equalization of current indicators, elimination of impulse noise, etc. Again, depending on the application, we can talk about working in single and three-phase power networks - accordingly, the devices are divided into 220- and 380-volt.
Through electronic control panels, the user can configure the operating parameters of the relay. What does this mean in practice? A relay with a digital interface and an LED display is supplied with the relay, in which current indicators are reflected. Using the controls on the same panel, threshold values are set for monitoring the rated current, voltage, setting contact groups, turning on and off individual functional units of the equipment. The relay is mounted on a complete DIN rail, which in some versions can be connected to a home computer.
Timer relays
Also, these devices are called workflow time controllers. They are compact relays designed to set the shutdown and turn-on times for given hours and minutes. Multifunctional timers of this type provide several programmable modes that allow you to configure the equipment and working configurations for weeks and days, indicating different connection sessions. According to the design and method of supply, the following types of time relays are divided:
- Rosette. Directly connected to a 220 V network and do not require cabling.
- Wired. They can be installed in any place where the electrical circuit passes. The device is introduced into the network through contactors.
- Standalone. Completely independent from the mains devices, operating on batteries or accumulators.
Varieties of thermal relays
The devices are designed for a wide range of protective functions, including the prevention of phase asymmetry, overloads, jamming of rotor mechanisms and delaying the start. The types of thermal relays should be divided according to the voltage, design and installation method. As for the network parameters, the nominal voltage can be 220, 380 and 660 V. That is, the devices can be used even in heavy industry, serving high-power production units. The design and installation method in the case of household models provides for both a separate connection and installation in combination with contactors of a suitable format. In the case of industrial devices, PML magnetic starters for remote control can also be used.
Control level relay
This device can be based on an electrical circuit and can be installed using a DIN rail. But besides this, the design will include a filling control sensor. In its quality can be various devices and devices that allow you to measure the level of liquids. The simplest models of such regulators are represented by float meters. At the moment of reaching the set filling threshold, the circuit is opened in the electric circuit and the equipment stops supplying the working medium. According to a similar principle, pressure switches operate, the types of which are disabled by the execution of the pressure gauge. It can be electronic or mechanical. The former also act on the winding and the anchor mechanism for opening the circuit, while the latter programmatically control the work process by starting or stopping the target units.
Relay for phase monitoring
Another variation of the electrical controller of the network parameters, acting on the principle of automatic regulation. Typical models, in particular, monitor voltage in energy converters and generators. The symmetry of this quantity and the presence of current as such are estimated. Most often, such devices are used in industrial fields to regulate the operation of induction motors. Given the specifics of the application, manufacturers provide a high level of protection for the relay itself. What is this in terms of structural implementation? These are the characteristics of the case and additional shells, determined by the security class. If domestic regulators are marked on this indicator IP 20, then industrial regulators are IP 40. This degree of protection involves the presence of isolation from foreign bodies, impact resistance and the ability to use the device at temperatures from -10 to 50 degrees.
Automotive Relays
Transport electrical engineering also cannot do without network regulators, through which climatic equipment, electronic assistants and multimedia equipment work. Such relays are installed in the dashboard or next to the load, and control is carried out through small buttons with thin eyeliner. As a rule, two types of automotive relays are used:
- With a pair of short circuit contacts.
- With three switches.
The difference is that the "three" at the time of activation of the device closes to a common contact, and its pair is turned off. There are also specialized versions of automobile regulators for certain groups of equipment. For optics, for example, relays with improved sealing in the form of compound filling are intended. This is necessary to enable the switch to be located in close proximity to the headlights.
What are the criteria for choosing a device?
The main principle of choice is to correctly determine the operating ranges of equipment. These can be voltage, current, temperature, or altitude measurement spectra. Next, find the best way to present the data. Traditional types of relays are guided by the minimum list of control information and practically do not give a complete picture of the working process. The latest models can reflect device information through displays of various shapes and sizes. The most ergonomic and functional models have control panels with sensors and programmable modules. As for the manufacturers, the most famous and reliable companies include ABB, SVEN, Orbis, and Novatek. The cost of devices starts from 1000-1200 rubles. The upper level is in the range of 3000-3500 rubles.
Finally
The use of electrical regulators is difficult to attribute to the domestic sphere, since they still perform specialized control tasks. Nevertheless, there are areas in which ignorant people have to deal with similar equipment. So, an ordinary homeowner may well be faced with the need to install an engineering relay. What it is? This is one of the most common types of electrical regulators that serve domestic boiler plants, radiators and other powerful electrical equipment. Theoretically, you can do without them, but in this case the reliability and stability of the equipment decreases.