Technical characteristics of circuit breakers

Purpose

First of all, let's look at what a circuit breaker( AB) is.

AB is a device that disconnects the electric power in a certain section of the wiring for the following reasons:

• occurrence of a short circuit;
• network overload;
• voltage surges.

In addition, this device can be used to "remove" the voltage in a certain area of ​​the wiring through operational shutdown( the measure is extremely rare).

In simple words, AB is necessary to protect electrical appliances when the wiring fails.

To your attention video lesson in which there is a full explanation of what a circuit breaker is and how it operates:

Construction

To date, there are many different products for disconnecting current in the network. Each of the devices has its own specific design, so in this article we will consider an example with a modular machine.

So, the circuit-breaker device consists of four main parts:

• Contact system( movable and fixed).The movable contact is connected to the control lever, and the fixed contact is installed in the housing itself. The power is cut off by pushing the movable spring contact, after which the network is opened.
• Thermal( electromagnetic) release. The element with which the contacts are opened. Thermal release - a bimetallic plate, which is bending, opens the contacts. Bending occurs due to heating by current( if its value exceeds the nominal value).Such disengagement occurs at elevated loads on the power line. The effect of the magnetic release is instantaneous, due to the occurrence of a short circuit. The overcurrent provokes the motion of the solenoid core, which drives the contact disengaging mechanism.
• Arc suppression system. This part of AB is represented by two plates of metal, which neutralize the electric arc. The latter occurs when the chain is broken.
• Control mechanism. For manual disconnection a special mechanical lever or button( in other types of AB) is used.

We also bring to your attention a more detailed design of the circuit breaker:

In this video example, the design and operation principle of AV is clearly demonstrated:

Technical characteristics of the

Any circuit breaker has its own individual characteristics, by which we select the appropriate model.

The main technical characteristics of the circuit breaker are:

General classification

I would also like to give you the most generalized classification of circuit breakers for the home. To date, the products are divided into the following attributes:

• Number of poles: one, two, three or four. Single-pole and bipolar circuit-breakers are commonly used in single-phase wiring. The last two options are used for a three-phase power supply.
  
  
• Type of drive. The device can be controlled manually( manual drive) or at a certain distance( electric drive).
• Presence / absence of current limiter. In the first case, breaking the circuit with short-circuit is faster, becauseThe current limiter protects the wiring from the short-circuit current limit values.
• Type of release. The purpose and types of these circuit-breaker design elements are discussed above. Let us repeat again that the electromagnetic release serves to protect against short-circuit currents, and the thermal release from overload currents.
• Product selectivity / nonselectivity. This function allows you to adjust the response time of the AB.
• Fastening method. Usually the fastening is represented by a retractable or stationary fixative. In the first case, AB is installed on a DIN-rail known to all electricians( as shown in the photo), in the second case, the installation is carried out in the frame of the electrical board.

Also products can be classified according to the degree of protection IP, amperage, the short-circuit current and the method of connecting the wires( or rather, conductors).

That's all you need to know about the device, the principle of operation and the assignment of circuit breakers. We hope that the information has become useful and new for you.
Also read:

• How to choose the RCD for the house
• Which is better: the diafi-automat or the RCD
• Why does the RCD