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First of all, we will understand what a circuit breaker (AB) is. The machine is a protective device that cuts off electricity in a certain section of wires for the following reasons:

• A short circuit occurs.
• Network congestion.
• Mounting power.

In addition, this device can be used to “relieve” Voltage in a particular section of wires by switching off (the event is extremely rare).In simple words, the purpose of a circuit breaker is to protect electrical appliances when the wires break.

As for the scope of automatic machines, it is possible both in domestic conditions (protection of houses and apartments), and at industrial enterprises. Circuit breakers are used in all areas of the electrical power industry.

Building

Today, there are many different products to stop the current in the network. Each device has its own design, so in this article we will consider an example with a standard machine.

Therefore,the circuit breaker consists of four main parts:

• Communication system (mobile and fixed). The movable contact is connected to the control lever, and the fixed one is installed in the housing itself. Power failure occurs by pushing the movable contact with the spring, after which the grid opens.
• Thermal (electromagnetic) release. An item with which contacts are opened. The thermal release is a bimetallic plate that bends and opens the contacts. Arcing occurs due to heating by current (if it exceeds its nominal value). This disengagement occurs when loads on the power line increase. Magnetic release is instantaneous due to short circuit. The excess current provokes the movement of the solenoid core, which activates the contact disconnection mechanism.
• Arc extinguishing system. This part of the machine represents two plates of metal, neutralizing the electric arc. The latter occurs when a chain break occurs.
• Control mechanism. For manual closing, a special mechanical lever or button is used (in other types of AB).

Technical Specifications

The main technical characteristics ofthe circuit breaker are:

• Voltage (Un). This value is specified by the manufacturer and is indicated on the front panel of the device.
• Rated current (in). It is also set by the factory and represents the maximum current value at which the protection will not operate.
• Current operating rating of the version (Ipн). If the current in the network increases to 1.05 * Irn or 1.2 * Irn, the process will not occur for some time. This value should be less than the rated current.
• Short circuit response time. When a short circuit occurs, the device turns off after a certain period of time current flows through the device (response time). It is also installed by the manufacturer.
• Maximum switching capacity of the circuit breaker. The value of transient short circuit currents at which the device can operate normally.
• Triggers the current setting. If this value is exceeded, the device trips the circuit and immediately disconnects it. Here the products are divided into 3 types: B, C, D. The first type is used when installing a long electrical line, the operating range is 3-5 rated operating currents of release (Ir). The type C device operates in the range of 5-10 values ​​and is used in lighting circuits. Type D is used to protect transformers and electric motors. Its working range is from 10 to 20 Irn.

General classification

I would also like to introduce you to the most general classification of circuit breakers for the home. Today, products are usually divided according to the following criteria:

• Number of columns: one, two, three or four. Single-pole and double-pole circuit breakers are commonly used for single-phase wiring. The last two options are used for three-phase power supplies.

  

  

  

  

• Driving type. The device can be controlled manually (manual drive) or at a certain distance (electric drive).
• Presence/absence of the current limiter. In the first case, breaking the circuit occurs faster, because the current limiter protects the wires from the limits of short-circuit current.
• Version type. The purpose and types of these structural elements of circuit breakers we considered above. We repeat once again that electromagnetic release serves to protect against short-circuit currents and thermal – from overload currents.
• Selectivity/non-selectivity of the product. This function allows you to adjust the AB response time.
• Installation method. Usually, the stand is represented by a retractable or fixed stabilizer. In the first case, the AB is installed on a well-known to all electricians DIN rail (shown in the photo), in the second, the installation is carried out in the frame of the electrical panel.

Products can also be classified by protection IP grade, current, short circuit current limit and wiring method.

That’s all you need to know about the device, principle of operation and purpose of circuit breakers. We hope that the information was useful to you, and now you know how the machine works, what it consists of and what its purpose is.