In an electrician, all processes of closing and opening a network are usually called switching. These functions are performed by special equipment. It is installed in various circuits and ensures the normal functioning of the system. Switching devices are devices that are designed to supply or stop the flow of electric current into the network.
Today, many varieties of the presented units are used. They differ in design and specifics of action. To choose the right unit, it is necessary to consider the existing types and their features.
general characteristics
The purpose of switching devices is reduced to the process of transmitting electricity due to the closure and opening of the circuit. Today, all existing units of this type can be divided into two categories. The first group includes contact (mechanical) devices, and the second - non-contact (semiconductor or gas-discharge) varieties.
The most common switching type devices are switches, circuit breakers, contactors, relays, fuses. They have certain features that must be considered when choosing. It is necessary to purchase a switching device in accordance with the operating conditions.
The presented units can have several poles in their design. Their number can be from one to four. In accordance with this indicator, devices are also divided into groups. Most often, bipolar products are on sale. They have two positions - “off” or “on”.
Circuit breaker
Switching devices can be controlled manually or by contactlessly responding to environmental changes. The simplest option of a mechanical type is a knife switch. Its management is performed manually.
The device is used for switching in electric circuits with a voltage that does not exceed 660V. On sale are one, two and three pole varieties of units. With the help of a knife switch, the circuit is disconnected under voltage or without it. The famous manufacturer in our country of the presented equipment is the Kursk Electrical Equipment Plant.
Knife switches can be domestic or industrial. The first category is designed for use in low-voltage networks, and the second - in high-voltage. This is a popular equipment that is used almost everywhere.
Varieties of knife switches
Switching devices, which belong to the type of circuit breakers, in turn, are divided into subgroups. Allocate a disconnector, a switch and a short circuit. In the first case, the device interrupts the supply of electricity to the circuit, which has a small current strength. This type of instrument is used to inspect or repair the system. The disconnector has a distance between the contacts for insulation.
Switches transfers electric current from one circuit to another. Short circuit is not made and is not used in modern equipment. It creates a short circuit.
On sale are devices that combine the presented functions. For example, it could be a switch-disconnector. This is a circuit breaker with a camera for extinguishing the arc. It can work in either one or two directions. If in such a switch there is no chamber for extinguishing the arc, this device belongs to the group of disconnectors.
Switch
A general-purpose circuit breaker is a switching device up to 1000 V (alternating current) and up to 440 V (direct current). This unit belongs to devices of mechanical type. It can turn on, pass or turn off the supply of electric current. It helps protect electrical networks from overloads, critical voltage drops or short circuits. Classical in this case is the RCD circuit (presented below).
I - RCD.
II - Electric consumer (measuring device).
A circuit breaker can control the network. To do this, their design provides for the presence of various drives.
There are many different modifications of the presented devices. This allows you to apply them in almost all areas of energy. Most often in residential and industrial networks they use packet types of circuit breakers.
The main types of switches
The presented switching devices have many options. Automatic varieties include residual current circuit breakers and differential switches. In the first case , the RCD circuit can protect a person from electric shock in the event of an emergency. Differential circuit breakers are a special type of circuit breaker. In its design, the RCD is connected to a switch. This provides comprehensive protection against electric shock.
Batch switches are used for circuits with a voltage of 110-380 V. They are installed to control asynchronous motors, complete devices. Such switching devices are assembled on the surface of a square shaft. The system in this case includes a certain number of such units. There is a handle and a mechanism for fixing it. When it is rotated, the shaft is driven. The switching cams of the device open the circuit.
General-purpose circuit breakers are switching devices up to 1000 V. They can work both with alternating and direct current. They include a drive, trip units.
Drive and trip units
The drive of the switching device is driven manually or non-contact. There are systems with a combined control system. Switching off is done using springs. They are driven after the release is disconnected. This part eliminates the possibility of holding the contacts in the on position in the event of an emergency.
The trip unit is a system of ligamentous articulated levers. They connect the actuator with movable contacts, which, in turn, are adjacent to the breaking spring.
It is the releases that are responsible for maintaining the required parameters of the circuit they protect. If there are deviations from the normal value in the system, these elements turn off the power.
Automatic uncoupling methods
Protective switching devices have relays in their design. They are part of the releases. Relays can be electromechanical or statistical. Semiconductor materials are monitored and compared to predetermined parameters. This principle is embedded in introductory machines.
Electromechanical varieties can be made on the basis of electrothermal, electromagnetic or combined elements. An introductory switching device of the type presented is installed in apartments, houses, industrial facilities, etc.
The trip units may not have a set time interval during the operation. Also on sale are devices with independent exposure or tripping with an inverse dependence on current.
Other varieties
Switching devices also include fuses, contactors and relays. In the first case, interruption is performed by the destruction of special elements. They conduct current.
Contactors are used for power on, power off operations. This category of devices includes starters, rheostats, starting and ballast type. The electrical relay can be a separate device. It serves to open the network at specified parameters.
Having considered the switching devices used in modern electrics, you can make the right decision when choosing the equipment presented.