2024 Author: Howard Calhoun | [email protected]. Last modified: 2023-12-17 10:16
A circuit breaker is a switching device that conducts a permissible electric current and turns off the power when it exceeds the nominal value. It serves to protect electrical circuits from overloads. A single-pole circuit breaker provides protection for only one wire.
Design and principle of operation
The main characteristics of the circuit breaker are the rating and tripping speed. A single-pole machine is triggered by two mechanisms: thermal and electromagnetic releases. The first disconnects the circuit in the event of an increased load for a long time, and the second - instantly, in case of a short circuit.
The thermal protection device is a bimetal plate. When a current above the maximum allowable passes through it, it gradually heats up and bends, pushing the lever that turns off the machine. After cooling, the plate returns to its place, and the switch is ready for operation again. To put it into operation, you must connect it manually.
An electromagnetic device consists of a coil with acore. When a short circuit current passes through the winding, an electromagnetic field arises that moves the core, which turns off the machine. In this case, the power contacts open, de-energizing the circuit. Since a large current passes through them, an arc occurs. It enters the arc chute, where parallel metal plates are located. With their help, the arc breaks up and breaks up.
The machine is also used as a switch by manually turning the control knob.
Application of single pole circuit breaker
Wiring in the apartment branches into several groups. The connection of a single-pole machine is made in the break of the phase wire. It is mounted on a DIN rail, and a power wire is inserted into its upper clamp. The wire to be protected is connected to the lower terminal. If the wires are pressed with screws, they should be tightened with a little force.
As a rule, the upper terminals of single-pole circuit breakers are connected to the power supply through a comb, and the lower terminals are wired into groups. Multiple redundant units can be installed.
Marking
Circuit breakers have a standard marking that reads from top to bottom.
The body of the device has the values of its main parameters:
- trademark - EKF;
- series number - BA47-29;
- characteristic "C" and rated current for a single-pole machine - 25A;
- rated voltagepower supply - 230/415 V;
- maximum permissible short-circuit breaking currents - 4500 A;
- current limiting class - 3.
You can identify the manufacturer by the brand. It is advisable to choose vending machines from well-known brands: Legrand, ABB, IEK, EKF, etc.
The inscription on the machine 230/415 V means that the device is capable of operating in single-phase and three-phase networks. Most devices in household wiring have this capability.
Rated current is the amount of current at which the machine will not work for a long time. If it is increased by 13%, it will turn off in an hour. The larger the value of the continuously flowing current, the faster the operation. The main purpose of the machine is to prevent overheating of the wiring when the load is connected. It is important that the current allowed for the conductor be greater than the rating of the device, and not vice versa.
Time-current characteristic "C" means that the operation of both tripping mechanisms will occur after a fivefold increase in the rated current. It is suitable for lighting and most household appliances. If there is an automatic machine with such a characteristic in the entrance, then in the apartment panel it is necessary to install an apparatus with the characteristic "B" on the main input. This means that with all other identical characteristics, it will work faster. Then you don’t have to run to the entrance and turn on the machine there. Choosing the right device with the right characteristic ensures the desired trip selectivity.
The maximum allowable tripping current shows its maximum value, at whichthe machine is able to turn off at least once.
Number of poles
If you choose a single-pole or two-pole machine, it is important where to install it. A two-terminal network should be installed at the main input of the apartment shield. This will reliably de-energize the house wiring during repairs, when the phase should be disconnected along with the neutral. When 2 wires are introduced into the house, you can install an automatic machine with one pole. In the presence of a grounding conductor, a two-pole input machine is installed.
A single-pole machine is connected to each branch of the home network along with an RCD.
If the apartment is powered by a three-phase circuit, a four-pole machine should be installed at the main input.
Single-pole machine: price
Single-pole machine is cheaper than others in the line with a large number of poles. Products of domestic manufacturers can be bought for 40-50 rubles, while imported brands cost 150-200 rubles. It is important to choose devices according to the quality-price ratio, and not those that are cheaper.
Mistakes when choosing machines
When choosing circuit breakers, users make a number of mistakes.
- Focus on the total power consumption instead of protecting the wiring from overload. Installing a powerful machine on weak wiring leads to its overheating. It is important to select the device according to the wire section.
- Often the same machines are installed on all lines, due to which some of thethey are overloaded. Sockets need 25 A protection, and lighting needs 16 A. The line leading to the garage can be heavily loaded with powerful power tools. Here it is advisable to install the machine at 32 A.
- Don't choose slots based on price. It is better to buy products of well-known brands, where quality is guaranteed.
Conclusion
In order to select the desired single-pole machine without errors, you should understand the markings printed on the case on the front side. The characteristics of the device are selected depending on the type of connected load and the cross section of the wiring.
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