To protect the electrical circuit from the consequences of a short circuit, namely from the effects of a high current, an automatic two-pole switch is used. Structurally, it represents two single-pole devices with a combined key and an internal locking mechanism. It is not recommended to install two single switches instead of double ones, since in case of a short circuit, only one circuit will break.
Content
- Device characteristics
- Design features
- The principle of operation of the main elements
- Popular models
- Installation and connection of the machine
Device characteristics
The design of the two-pole device is made taking into account the observation and comparison of the functioning of two electrical circuits. They are usually installed in a single electric line to control two of its sections. There are 2 types of these devices available:
- With one pole blocking and standard neutral connection.
- With protection of both lines and their simultaneous switching.
The first type is installed at the input to the electric line, and it controls the functioning of the phase and neutral conductors. In addition, a ground wire can be used with this device. The second type works in circuits of one circuit and controls the operation of two sections under different current loads.
Design features
A two-pole switch, like a single-pole one, is used in a single-phase electrical network. Structurally, they are no different from each other. The only difference between the two is the way they are connected to the electrical network. A single-pole circuit breaker is installed in the break of the phase wire, and the neutral wire runs along a separate line.
The two-pole circuit breaker is distinguished by the presence of protective functions that ensure that each pole is locked. In case of an emergency, on any part of the electrical circuit, one pole protection is triggered, which turns off the entire machine. The main elements of the device:
-
frame; - contact module;
- electromagnetic control system;
- electric arc extinguishing device;
- release.
The body and cover of the machine are made of a material that does not allow electric current to pass through. Usually, plastic, textolite and other polymeric materials are used for this. The main functional units are located inside the body. Free terminals are mounted in the cover and connected to the main contacts.
The device is turned off both manually and automatically. In the event of an overload in the electrical circuit, the machine instantly turns off with such an effort that it is impossible with your hands to prevent the operation of the protective device. According to the principle of operation of a two-pole switch, a four-pole circuit breaker operates in a three-phase electrical circuit.
The principle of operation of the main elements
The main elements of the circuit breaker include: thermal release device, electromagnetic protection mechanism. When a short circuit occurs, the current in the electrical circuit increases several times.
This situation can lead to failure of wires and household equipment. The design of electromagnetic protection includes:
- coil;
- core (solenoid);
- spring;
- moving contacts.
The spring, inside which the solenoid is located, connects the thermal release with moving contacts in series. The operating current is too low for the magnetic mechanism to operate.
When overcurrents occur, the coil pulls in the core, compresses the spring, and the contacts open. In the normal state, under the influence of the spring, the contacts are connected again. The thermal release consists of a bimetallic plate, a lever and contacts.
Such a device works somewhat slower than an electromagnetic one. This is due to the fact that it takes some time to heat the bimetallic plate. It also differs in that it does not respond to a short-term increase in current.
Popular models
Before choosing the right machine, you should pay attention to the technical characteristics of the device. In addition, the case is marked with Latin letters, which denote the breaker trip time. The most popular are:
-
2P 10A DEKraft VA-101 is a two-pole circuit breaker that can withstand an increase in current up to 10 thousand. ampere. The device has a monolithic front panel and is easy to install. - ABB E214-25-202 - used in electrical networks with voltages from 24 to 250 V. Has a breaking capacity at short-circuit current up to 3 thous. ampere. The device is manufactured by the Swedish-Swiss company ABB.
- TDM BA47-63 2P 32A is a modular circuit breaker from Russian manufacturers. Rated operational current - 32 A, voltage range - from 230 to 400 V. Notched contacts prevent wires from overheating. The device is installed both vertically and horizontally. The supply wires are connected to the top or bottom terminals.
The most reliable machines are considered to be manufactured by ABB and the French company Legrand.
Installation and connection of the machine
The device must be checked before installation in the electrical circuit. for some indicators, namely: it must fully comply with the technical parameters the corresponding circuit, the body has no cracks or damage, the key should operate easily with characteristic click.
If the machine is mounted on a DIN rail, then the connection point should not have any characteristic damage. The connection is made with copper wires, on each of which a corresponding lug is installed. If the wires are aluminum, then the TAM-7 end elements are mounted, which must comply with the GOST parameters.
All mains conductors are connected to the contacts located at the top of the device. After connecting, the wires should not exert any force on the terminals of the machine, otherwise the contact will gradually weaken. After connecting the wires, the device is checked for the quality of the insulation, its performance test is carried out.
