In electrics, all the processes of closing and opening a network are commonly called switching. These functions are performed by special equipment. It is installed in a variety of 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 to the network.
Today, many varieties of the units presented are used. They differ in design and specificity of action. To choose the right unit, you need 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 closing 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 group includes non-contact (semiconductor or gas-discharge) varieties.
The most common switching devices are switches, circuit breakers, contactors,relays, fuses. They have certain features that must be considered when choosing. The purchase of the switching device must be in accordance with the operating conditions.
The presented units may 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".
Knife switch
Switching devices can be controlled manually or by non-contact response to changes in the environment. The simplest variant of the mechanical type is the knife switch. It is controlled manually.
The device is used for switching in electrical 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. A well-known manufacturer in our country of the presented equipment is the Kursk electrical apparatus plant.
Knife switches can be domestic or industrial. The first category is designed for use in a low-voltage network, and the second - in a high-voltage network. This is a sought-after 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. Allocatedisconnector, switch and 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 contact spacing for isolation.
Switches transfer electrical current from one circuit to another. The short circuit is not produced and is not used in modern equipment. It creates a short circuit.
On sale are devices that combine the functions presented. For example, it can be a switch disconnector. This is a knife switch with a chamber for extinguishing the arc. It can work in both one and two directions. If there is no chamber for extinguishing the arc in such a switch, this device belongs to the group of disconnectors.
Switch
The 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 mechanical type devices. 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. The classic in this case is the RCD circuit (presented below).
I - RCD.
II - Electrical consumer (measuring instrument).
The circuit breaker can control the network. To do this, their design provides for the presence of variousdrives.
There are many different modifications of the presented devices. This allows them to be used in almost all areas of energy. Most often, package types of switches are used in domestic and industrial networks.
Main types of switches
The presented switching devices have many options. Automatic varieties include residual current devices and differential switches. In the first case, the RCD circuit is able to protect a person from electric shock in the event of an emergency. Differential switches are a special type of switch. In its design, the RCD is connected to the switch. This provides comprehensive protection against electric shock.
Packet switches are used for circuits with a voltage of 110-380 V. They are installed in order to control asynchronous motors, complete devices. Such switching devices are assembled on the surface of a square shaft. In this case, the system includes a certain number of such units. There is a handle and a mechanism for its fixation. When it turns, the shaft is set in motion. The switching cams of the device open the circuit.
General purpose circuit breakers are switching devices up to 1000 V. They can operate both with alternating and direct current. They include a drive, releases.
Drive and releases
The drive of the switching device is driven manually orcontactless way. There are systems with a combined control system. Switching off is done by means of springs. They are set in motion 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 release is a system of ligamentous articulated levers. They connect the actuator to the moving contacts, which in turn are adjacent to the opening spring.
It is the releases that are responsible for maintaining the required parameters of the circuit they protect. If the system experiences deviations from the normal value, these elements turn off the power.
Auto trip methods
Protective switching devices have relays in their design. They are part of the breakers. Relays can be electromechanical or static. Produce control and comparison of the specified parameters of semiconductor materials. This principle is embedded in the introductory machines.
Electromechanical varieties can be made on the basis of electrothermal, electromagnetic or combined elements. The input switching device of the presented type is installed in apartments, houses, industrial facilities, etc.
Releases may not have a set time interval when tripping. Also on sale are devices with independent exposure or operation with inverse current dependence.
Other varieties
SwitchingThe apparatus also includes fuses, contactors and relays. In the first case, interruption is performed by destroying special elements. They conduct electricity.
Contactors are used for power on, power off operations. This category of devices includes starters, starting and ballast-type rheostats. The electrical relay may be a separate device. It serves to open the network with the given parameters.
Having considered the switching devices used in modern electrics, you can make the right decision when choosing the presented equipment.
