A high-voltage circuit breaker is an electrical switching device used to cut off and isolate circuits in high-voltage power systems. It is mainly used in power systems with a rated voltage exceeding 1 kV (kilovolts), including substations, power plants, industrial power systems, etc.circuit breaker types

 

The main function of high-voltage circuit breakers is to break circuits in power systems to protect equipment and personnel from circuit failures. When an overload, short circuit or other fault occurs in a high-voltage circuit, the high-voltage circuit breaker can quickly cut off the current and prevent excessive current from flowing through electrical equipment and wires to avoid equipment damage, fire and other dangers.

 

A low-voltage circuit breaker is a switching device that can not only switch on and off normal load current and overload current, but also switch on and off short-circuit current. In addition to the control function in the circuit, the low-voltage circuit breaker also has certain protection functions, such as overload, short circuit, undervoltage and leakage protection. There are many classification methods for low-voltage circuit breakers. According to the category of use, there are selective type (the parameters of the protection device can be adjusted) and non-selective type (the parameters of the protection device cannot be adjusted). According to the arc extinguishing medium, there are air type and vacuum type. Low-voltage circuit breakers are widely used in feeder lines at all levels of low-voltage power distribution systems, power control of various mechanical equipment, and control and protection of power terminals.

 

The main function of low-voltage circuit breakers is to break the circuit in low-voltage circuits to protect equipment and personnel from circuit failures. When an overload, short circuit or other fault occurs in a low-voltage circuit, the low-voltage circuit breaker can quickly cut off the current and prevent excessive current from flowing through electrical equipment and wires to avoid equipment damage, fire and other dangers.circuit breaker switch

 

Ⅰ. Types of high voltage circuit breakers

 

1. Air circuit breaker

 

An air circuit breaker is a circuit breaker that uses air as the arc extinguishing medium. It is a common low-voltage circuit breaker widely used in low-voltage power systems, industrial equipment and buildings.

 

The working principle of the air circuit breaker is to pass the current through a series of metal contacts, so that the arc is formed between the contacts, and then the arc is cooled and extinguished by the forced flow of air. When an overload, short circuit or other fault occurs in the circuit, the air circuit breaker can quickly cut off the current and extinguish the arc through the arc extinguishing process to prevent excessive current from flowing through electrical equipment and wires.

 

The structure of the air circuit breaker is relatively simple, consisting of metal contacts and a forced-ventilated chamber, with reliable operation and arc extinguishing functions. The structure of the air circuit breaker is relatively simple, consisting of metal contacts and a forced-ventilated chamber, with reliable operation and arc extinguishing functions. Air circuit breakers are suitable for a variety of application scenarios in low-voltage power systems, industrial equipment and buildings, such as distribution boards, generator protection, electrical load control, etc.

 

2. Vacuum circuit breaker

 

A vacuum circuit breaker is a switching device used in power systems to open or close an electrical circuit. There is a vacuum-enclosed cavity inside the vacuum circuit breaker, and the gas in it is evacuated to form a vacuum environment. When the breaker opens, the current flow between the two breaker contacts creates an arc. In a vacuum environment, due to the lack of gas molecules, the arc cannot be maintained and is quickly extinguished. This arc extinguishing feature makes the vacuum circuit breaker have the ability to quickly break the current and reliably extinguish the arc.

 

3. Gas circuit breaker

 

A gas circuit breaker is a type of switching device used in power systems to break or close a circuit. It uses gas as the arc extinguishing medium to extinguish the arc to prevent fire, equipment damage and personal injury. The working principle of the gas circuit breaker is to generate an arc when breaking the circuit and put it in a specific gas environment. These gases have high insulating and arc extinguishing capabilities. When an arc is formed, the arc extinguishing gas is released into the arc area, extinguishing the arc by dissipating the arc energy. The arc extinguishing process is usually accompanied by a pressure rise and heat release.

 

4. Magnetic blower circuit breaker

 

A magnetic blower circuit breaker is a type of circuit breaker used in power systems to open or close circuits. It uses the force generated by the magnetic field to cut off the current and extinguish the arc. The working principle of the magnetic blowing circuit breaker is based on the action of magnetic field force. When the current exceeds the set value or a fault occurs, the magnetic field inside the circuit breaker is activated to generate a magnetic force. This magnetic force pulls the arc apart and quickly cuts off the current flow. At the same time, the force of the magnetic field also blows the arc out of the current path, extinguishing the arc. Magnetic blown circuit breakers usually consist of a magnet and a movable contact. A magnet generates a magnetic field by passing an electric current through a coil. When the current exceeds the rated value, the force of the magnetic field will cause the movement of the movable contact, which will quickly open the circuit. During the disconnection process, the magnetic force also blows out the resulting arc, ensuring complete interruption of the circuit.

 

5. Oil circuit breaker

 

An oil circuit breaker is a type of circuit breaker used in power systems to open or close a circuit. It uses insulating oil as the arc extinguishing medium, and uses the properties of oil to extinguish the arc. The working principle of the oil circuit breaker is based on guiding the arc into the insulating oil, and using the insulating and arc extinguishing ability of the oil to extinguish the arc. When the current exceeds a set value or a fault occurs, an electrical arc is generated in the circuit, which can cause serious damage. Oil circuit breakers usually consist of a circuit breaker unit and an insulating oil tank. When the circuit breaker contacts open, an arc is formed between the contacts and is guided by the insulating oil bath. Insulating oil has high insulation and arc extinguishing ability, which can absorb the energy of the arc and cool the arc rapidly to make it extinguished.

 

Ⅱ. Types of low-voltage circuit breakers

 

1. Air circuit breaker

 

An air circuit breaker is a type of circuit breaker used in power systems to open or close circuits. The working principle of the air circuit breaker is to generate an arc when breaking the circuit and place it in a specific air environment. The arc is separated, cooled and extinguished in air. In order to enhance the arc extinguishing effect, air circuit breakers usually guide air to the arc area through nozzles or injectors to accelerate the cooling and extinguishing of the arc. Air circuit breakers usually consist of a circuit breaker unit and a gas compressor. When the circuit breaker contacts are opened, an arc is formed between the contacts, which is cooled and extinguished by the compressed air generated by the gas compressor. Compressed air can effectively cool the arc and take away the generated heat, thus quickly extinguishing the arc.

 

2. Leakage circuit breaker

 

Leakage circuit breaker is a protective device used in power system to detect and break the leakage current in the circuit to prevent electric shock accidents and electric shock risks. The main function of the leakage circuit breaker is to monitor the current difference in the circuit. Under normal conditions, current flow through the phase and neutral conductors of the line is balanced. However, leakage current occurs when a leakage occurs, such as when a human body comes into contact with a live part or a line fault causes current to be lost through another path.

 

3. Molded case circuit breaker

 

Molded case circuit breakers are a common type of circuit breaker used to open or close circuits and provide overload and short circuit protection for circuits. It encapsulates the circuit breaker assembly in a plastic housing that provides electrical insulation and mechanical protection. Molded case circuit breakers usually consist of a case, tripping device, fuse or magnetic circuit breaker unit. The housing is made of heat-resistant plastic material that provides good insulation and mechanical strength. The trigger device is used to activate the circuit breaker to quickly cut off the current in the event of an overload or short circuit. Molded case circuit breakers have multiple protection functions. When the current in the circuit exceeds the set rated current value, the molded case circuit breaker will trigger the overload protection device to open the circuit breaker and cut off the current. In addition, when a short circuit occurs in the circuit, the electromagnetic breaker unit quickly cuts off the circuit by electromagnetic force, providing short circuit protection.

 

4. Miniature circuit breaker

 

A miniature circuit breaker is a common type of circuit breaker used to open or close a circuit and provide overload and short circuit protection to the circuit. The main features of miniature circuit breakers are their small size and quick disconnect capability. It usually uses a thermal magnetic protection device with overload and short circuit protection. When the current in the circuit exceeds the rated current value, the thermal protection device of the miniature circuit breaker will trigger, so that the circuit breaker will open quickly and cut off the current. At the same time, when a short circuit occurs in the circuit, the magnetic protection device will quickly cut off the circuit through electromagnetic force.

 

Ⅲ. The difference between high voltage circuit breaker and low voltage circuit breaker

 

High-voltage circuit breakers and low-voltage circuit breakers are circuit breakers used in power systems of different voltage levels. They have some differences in design, working principle and application.

 

1. Application fields: High-voltage circuit breakers are mainly used in high-voltage power systems such as power plants, substations, and power transmission and distribution networks to protect and control high-voltage circuits. Low-voltage circuit breakers are mainly used in low-voltage power systems in residential, commercial buildings, and industries to protect and control low-voltage circuits.

 

2. Breaking capacity: High-voltage circuit breakers need to be able to quickly and reliably break high-current and high-voltage circuits. High-voltage circuit breakers generally have a higher breaking capacity, which can withstand and cut off larger currents and short-circuit faults.

 

3. Structure and size: Due to the high voltage in the high-voltage power system, the design of high-voltage circuit breakers needs to consider higher insulation performance and arc extinguishing ability. High voltage circuit breakers are generally of larger volume and size to accommodate larger interruption and arc extinguishing equipment.

 

4. Voltage level: High-voltage circuit breakers are usually used in high-voltage power systems, and their rated voltages are usually in the range of kV or higher. Low-voltage circuit breakers are used in low-voltage power systems, and their rated voltages are usually below kilovolts.

 

5. Arc extinguishing medium: High voltage circuit breakers usually use gas or oil as the arc extinguishing medium to provide effective arc extinguishing capability under high voltage. Low voltage circuit breakers typically use air as the arc extinguishing medium because arc extinguishing requirements are lower at low voltages.

 

Ⅳ. Application field of high voltage circuit breaker and low voltage circuit breaker

 

1. Application field of high voltage circuit breaker

 

Industrial field: In the high-voltage power system in the industrial field, it is used to protect and control high-voltage equipment and circuits, such as motors, transformers and generators.

 

Power Plant: Circuits used to open or close high voltage generators and transformers.

 

Substation: used to protect and control medium and high voltage equipment and cable lines in substations.

 

Transmission lines: used to protect power transmission lines, including high-voltage transmission lines and connecting lines between substations.

 

2. Application field of low voltage circuit breaker

 

Industrial field: In the low-voltage power system in the industrial field, it is used to protect and control low-voltage equipment and circuits, such as motors, control panels, and power distribution devices.

 

Entertainment places and public places: used to protect circuits and equipment in entertainment places, public places and commercial facilities, such as theaters, hotels, shopping malls and exhibition centers, etc.

 

Residential and Commercial Buildings: Used to protect electrical circuits and socket circuits in residential and commercial buildings, including lighting circuits and electrical equipment circuits.

 

Ⅴ. Working principle of high voltage circuit breaker and low voltage circuit breaker

 

1. High voltage circuit breaker

 

High voltage circuit breakers usually use gas (such as hydrogen sulfide SF6) or oil as the arc extinguishing medium. Arcs form when a fault or overload occurs in an electrical circuit. The arc extinguishing medium generates high pressure gas or gas bubbles in the arc zone, which extinguish the arc by absorbing the energy of the arc and cooling the arc. Due to the high current and voltage in the high-voltage power system, the high-voltage circuit breaker needs to have higher breaking capacity and be able to quickly cut off large current and high voltage.

 

2. Low voltage circuit breaker

 

Low voltage circuit breakers usually use air as the arc extinguishing medium. Arcs form when a fault or overload occurs in an electrical circuit. The air in the arc chamber inside the circuit breaker rapidly diffuses, cooling the arc and opening the circuit. Because the arc energy of the low-voltage power system is small, the arc extinguishing ability of air is sufficient to extinguish the arc. Low-voltage circuit breakers have lower breaking capacity requirements because the current and voltage in low-voltage power systems are usually small.

 

High-voltage circuit breakers and low-voltage circuit breakers are also different in triggering devices. High-voltage circuit breakers usually use electromagnetic trigger devices. When the current in the circuit exceeds the rated value, the trigger device will generate electromagnetic force to quickly cut off the circuit. Low-voltage circuit breakers usually use a thermal-magnetic trigger device to trigger the action of the circuit breaker through changes in current and temperature.

 

Frequently Asked Questions

 

1. What is the difference between a high voltage circuit breaker and a low voltage circuit breaker in breaking capacity?

 

High voltage circuit breakers need to be able to quickly and reliably interrupt high current and high voltage circuits. The breaking capacity of a high-voltage circuit breaker refers to the maximum current or short-circuit current that it can safely cut off. Low-voltage circuit breakers have lower breaking capacity requirements because the current and voltage in low-voltage power systems are usually small. The breaking capacity of a low-voltage circuit breaker is measured by the rated short-circuit capacity, which means the maximum rated short-circuit current that the circuit breaker can reliably cut off. Rated short-circuit capacity is usually identified in kiloamperes.

 

2. What is the main function of a low-voltage circuit breaker in a low-voltage power system?

 

Overload protection, short circuit protection, overcurrent protection, electrical safety protection, control circuit, etc.

 

3. In a high-voltage power system, how does a high-voltage circuit breaker protect circuits and equipment?

 

High voltage circuit breakers are capable of detecting and handling short circuit faults in electrical circuits. When a short circuit occurs, that is, the current suddenly increases on an abnormal path, the high-voltage circuit breaker will quickly cut off the circuit to prevent excessive current from flowing through the wires and equipment, protect the wires and equipment from damage, and prevent the risk of fire. It can also maintain the stability of the power network by detecting faults in the power system and shutting down faulty circuits. They prevent the propagation of faults in the power system, keeping the power supply to other parts stable.