What size are electric machines? Types of circuit breakers - what types of circuit breakers there are. Topic: what types of electric machines are divided into, their types and classification
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Circuit breakers are devices whose task is to protect electric line from exposure to a powerful current that can cause overheating of the cable with further melting of the insulating layer and fire. An increase in current strength can be caused by too much load, which occurs when the total power of the devices exceeds the value that the cable can withstand in its cross-section - in this case, the machine does not turn off immediately, but after the wire heats up to a certain level. During a short circuit, the current increases many times over within a fraction of a second, and the device immediately reacts to it, instantly stopping the supply of electricity to the circuit. In this material we will tell you what types of circuit breakers are and their characteristics.
Automatic safety switches: classification and differences
Beyond devices protective shutdown, which are not used individually, there are 3 types of network circuit breakers. They work with loads of different sizes and differ in their design. These include:
- Modular AB. These devices are installed in household networks in which negligible currents flow. Typically have 1 or 2 poles and a width that is a multiple of 1.75 cm.
- Molded switches. They are designed to operate in industrial networks with currents up to 1 kA. They are made in a cast case, which is why they got their name.
- Air electric machines. These devices can have 3 or 4 poles and can handle currents up to 6.3 kA. Used in electrical circuits with high power units.
There is another type of circuit breaker for protecting the electrical network - differential. We do not consider them separately, since such devices are ordinary circuit breakers that include an RCD.
Types of releases
Releases are the main operating components of the automatic circuit breaker. Their task is to ensure that if the permissible value current to break the circuit, thereby stopping the supply of electricity to it. There are two main types of these devices, differing from each other in the principle of tripping:
- Electromagnetic.
- Thermal.
Electromagnetic type releases provide almost instantaneous operation circuit breaker and de-energizing a section of the circuit when a short circuit overcurrent occurs in it.
They are a coil (solenoid) with a core that is drawn inward under the influence of a large current and causes the tripping element to operate.
The main part of the thermal release is a bimetallic plate. When a current exceeding the rated value passes through the circuit breaker protective device, the plate begins to heat up and, bending to the side, touches the disconnecting element, which is triggered and de-energizes the circuit. The time it takes for the thermal release to operate depends on the magnitude of the overload current passing through the plate.
Some modern devices are equipped as an addition with minimum (zero) releases. They perform the function of turning off the AV when the voltage drops below the limit value corresponding to the technical data of the device. There are also remote releases, with the help of which you can not only turn off, but also turn on the AV, without even going to the distribution board.
The presence of these options significantly increases the cost of the device.
Number of poles
As already mentioned, the circuit breaker has poles - from one to four.
Selecting a device for a circuit based on their number is not at all difficult; you just need to know where they are used Various types AB:
- Single-pole circuits are installed to protect lines that include sockets and lighting. They are mounted on the phase wire without touching the neutral wire.
- The two-terminal network must be included in the circuit to which it is connected Appliances with sufficiently high power (boilers, washing machines, electric stoves).
- Three-terminal networks are installed in semi-industrial networks, to which devices such as borehole pumps or auto repair shop equipment.
- Four-pole AVs allow you to protect electrical wiring with four cables from short circuits and overloads.
The use of machines of different polarities is shown in the following video:
Characteristics of circuit breakers
There is another classification of machines - according to their characteristics. This indicator indicates the degree of sensitivity of the protective device to exceeding the rated current. The corresponding marking will show how quickly the device will react in the event of an increase in current. Some types of AVs work instantly, while others will take some time.
There is the following marking of devices according to their sensitivity:
- A. Switches of this type are the most sensitive and react instantly to increased load. They are practically not installed in household networks, using them to protect circuits that include high-precision equipment.
- B. These machines operate when the current increases with a slight delay. They are usually included in lines with expensive household appliances(LCD TVs, computers and others).
- C. Such devices are the most common in household networks. They are turned off not immediately after increasing the current strength, but after some time, which makes it possible to normalize it with a slight difference.
- D. The sensitivity of these devices to increasing current is the lowest of all types listed. They are most often installed in shields at the line approach to the building. They provide security for apartment automatic machines, and if for some reason they do not work, they turn off the general network.
Features of the selection of machines
Some people think that the most reliable circuit breaker is the one that can handle the most current, and therefore can provide the most protection to the circuit. Based on this logic, you can connect a machine to any network air type, and all problems will be solved. However, this is not at all true.
To protect circuits with different parameters, it is necessary to install devices with the appropriate capabilities.
Errors in the selection of AB are fraught unpleasant consequences. If you connect a high-power protective device to a regular household circuit, it will not de-energize the circuit, even when the current significantly exceeds what the cable can withstand. The insulating layer will heat up and then begin to melt, but no shutdown will occur. The fact is that the current strength destructive to the cable will not exceed the AB rating, and the device will “consider” that emergency situation did not have. Only when the melted insulation causes a short circuit will the machine turn off, but by then a fire may have already started.
We present a table that shows the ratings of machines for various electrical networks.
If the device is designed for less power than what the line can withstand and which the connected devices have, the circuit will not be able to operate normally. When you turn on the equipment, the AV will constantly knock out, and ultimately, under the influence of high currents, it will fail due to “stuck” contacts.
Visually about the types of circuit breakers in the video:
Conclusion
The circuit breaker, the characteristics and types of which we reviewed in this article, is very important device, which protects the electrical line from damage powerful currents. The operation of networks not protected by automatic circuit breakers is prohibited by the Electrical Installation Rules. The most important thing is to choose the right type of AV that is suitable for a specific network.
Surely many of us have wondered why circuit breakers so quickly replaced outdated fuses from electrical circuits? The activity of their implementation is justified by a number of very convincing arguments, including the opportunity to buy this type of protection, which ideally matches the time-current data specific types electrical equipment.
Do you doubt which machine you need and don’t know how to choose it correctly? We will help you find the right solution - the article discusses the classification of these devices. As well as important characteristics that you should pay attention to close attention when choosing a circuit breaker.
To make it easier for you to understand the machines, the material in the article has been supplemented clear photos and useful video recommendations from experts.
The machine almost instantly disconnects the line entrusted to it, which eliminates damage to the wiring and equipment powered from the network. After the shutdown has been completed, the branch can be restarted immediately without replacing the safety device.
If you have knowledge or experience performing electrical installation work please share it with our readers. Leave your comments about choosing a circuit breaker and the nuances of installing it in the comments below.
Overloads in electrical circuits are common. To protect electrically powered devices from such voltage surges, circuit breakers were invented. Their task is simple - to break the electrical circuit if the voltage exceeds the nominal limits.
The first such devices were the familiar traffic jams, which are still installed in some apartments. As soon as the voltage jumps above 220 V, they are knocked out. Modern types circuit breakers are not only plugs, but also many other varieties. Their great feature is that they can be reused.
Classification
Modern GOST 9098-78 distinguishes 12 classes of circuit breakers:
This classification of circuit breakers is very convenient. If you wish, you can figure out which device to install in your apartment and which for production.
Types (species)
GOST R 50345-2010 divides circuit breakers into following types(division occurs according to sensitivity to overloads), marked with letters of the Latin alphabet:
These are the main circuit breakers used in residential buildings and apartments. In Europe, the marking begins with the letter A - the most overload-sensitive circuit breakers. They are not used for domestic needs, but are actively used to protect power circuits of precision instruments.
There are also three more markings - L, Z, K.
Distinctive design features
Automatic devices consist of the following components:
- main contact system;
- arc chute;
- main drive of the tripping device;
- various types of release;
- other auxiliary contacts.
The contact system can be multi-stage (one-, two- and three-stage). It consists of arc extinguishing, main and intermediate contacts. Single-stage contact systems are mainly made from cermets.
To somehow protect parts and contacts from destructive forces electric arc reaching 3,000° C, an arc-extinguishing chamber is provided. It consists of several arc extinguishing grids. There are also combined devices that can extinguish a high-current electric arc. They contain slot chambers along with a grille.
For any circuit breaker there is a current limit. Thanks to the protection of the machine, it cannot cause damage. With huge overloads of such current, the contacts can either burn out or even weld to each other. For example, for the most common household appliances with an operating current from 6 A to 50 A, the maximum current can range from 1000 A to 10,000 A.
Modular designs
Designed for low currents. Modular circuit breakers consist of separate sections(modules). The entire structure is mounted on a DIN rail. Let's take a closer look at the design of a modular switch:
- On/off is done using a lever.
- The terminals to which the wires are connected are screw terminals.
- The device is fixed to the DIN rail with a special latch. This is very convenient because such a switch can be easily removed at any time.
- The entire electrical circuit is connected through movable and fixed contacts.
- Disengagement occurs using some kind of release (thermal or electromagnetic).
- The contacts are specially placed next to the arc chute. This is due to the occurrence of a powerful electric arc during disconnection of the connection.
BA series – industrial switches
Representatives of these machines are primarily intended for use in electrical circuits alternating current at 50-60 Hz, with operating voltage up to 690 V. Also used at direct current 450 V and current up to 630 A. Such switches are designed for very rare operational use (no more than 3 times per hour) and protection of lines from short circuits and electrical overloads .
Among important characteristics this series stands out:
- high breaking capacity;
- wide range of electromagnetic releases;
- button for testing the device with free release;
- load switches with special protection;
- remote control through a closed door.
AP series
The automatic circuit breaker is capable of protecting electrical installations and motors from sudden voltage surges and short circuits within the network. The launches of such mechanisms are not intended to be very frequent (5-6 times per hour). The automatic circuit breaker can be two-pole or three-pole.
All structural elements are located on a plastic base, which is closed with a lid on top. At large overloads, the free release mechanism is activated, and the contacts automatically open. In this case, the thermal release maintains the response time, and the electromagnetic release provides instantaneous disconnection when short circuit.
When operating the machine, it is advisable to adhere to the following conditions:
- When the air humidity is 90%, the temperature should not exceed 20 degrees.
- The operating temperature ranges from -40 to +40 degrees.
- Vibration at the mounting location should not exceed 25 Hz.
It is strictly prohibited to work in an explosive environment containing gases that destroy metal and windings, near clean energy heating devices, water flows and splashes, in places with conductive dust.
The variety of automatic switches allows you to easily select a device for an apartment or house. It is best to invite a specialist to install it.
Hello friends. The topic of the post is the types and types of circuit breakers (automatic circuit breakers, AB). I also want the results of the crossword puzzle tournament.
Types of machines:
Can be divided into AC, DC and universal switches operating at any current.
Design - there are air, modular, in a molded case.
Rated current indicator. The minimum operating current of a modular machine is 0.5 Amperes, for example. I’ll write soon about how to choose the right one rated current for the circuit breaker, subscribe to the blog news so as not to miss it.
Nominal voltage is another difference. In most cases, AVs operate in networks with a voltage of 220 or 380 Volts.
There are current-limiting and non-current-limiting.
All switch models are classified by the number of poles. They are divided into single-pole, double-pole, three-pole and four-pole circuit breakers.
Types of releases - maximum current release, independent release, minimum or zero voltage release.
Speed of operation of circuit breakers. There are high-speed, normal and selective automatic machines. They are available with or without a time delay, independent or inversely dependent on the current response time delay. Characteristics can be combined.
They differ in the degree of protection against environment— IP, mechanical influences, conductivity of the material. By type of drive - manual, motor, spring.
By the presence of free contacts and the method of connecting conductors.
Types of machines:
What does type AB mean?
Automatic circuit breakers contain two types of circuit breakers - thermal and magnetic.
Magnetic quick-release switch is designed for short-circuit protection. The tripping of the circuit breaker can occur in a time from 0.005 to several seconds.
The thermal breaker is much slower, designed to protect against overload. It works using a bimetallic plate that heats up when the circuit is overloaded. Response time ranges from a few seconds to minutes.
The combined response characteristic depends on the type of connected load.
There are several types of AV shutdown. They are also called types of time-current shutdown characteristics.
A, B, C, D, K, Z.
A– used for breaking circuits with long electrical wiring, serves as good protection for semiconductor devices. They operate at 2-3 rated currents.
B- For lighting network general purpose. They operate at 3-5 rated currents.
C– lighting circuits, electrical installations with moderate starting currents. These can be motors, transformers. The overload capacity of the magnetic circuit breaker is higher than that of type B switches. They operate at 5-10 rated currents.
D– used in circuits with active-inductive loads. For electric motors with high starting currents, for example. At 10-20 rated currents.
K– inductive loads.
Z– for electronic devices.
It is better to look at the data on the operation of switches of types K, Z in the tables specifically for each manufacturer.
That seems to be all, if there is anything to add, leave a comment.