The difference between a circuit breaker and an air switch

In modern electrical systems, circuit breakers and air switches (referred to as "air switches") are important protective devices that ensure the safe operation of circuits. Although they are often mixed in daily use, there are significant differences between the two in terms of functionality, structure, and application scenarios. This article will provide an in-depth analysis of circuit breakers and circuit breakers from multiple dimensions, including definition, working principle, structural design, protection performance, and applicable scenarios, to help readers fully understand the differences between the two and master how to make reasonable choices based on actual needs.
1、 Basic concept: What is a circuit breaker? What is an empty switch?
1. Circuit Breaker
A circuit breaker is a switching device that can automatically cut off a circuit under normal or abnormal conditions. It can not only deal with common faults such as overload and short circuit, but also has manual operation function. Some high-end models can even achieve multiple composite protection functions such as leakage protection and undervoltage protection.
Circuit breakers are widely used in power systems, industrial equipment, building distribution, and other fields, and are important components to ensure the stability and safety of electrical systems.
2. Air switch (Air Circuit Breaker)
Air circuit breaker is a specific type of circuit breaker, also known as air circuit breaker, which is characterized by using air as the arc extinguishing medium. Air switches mainly provide protection against overload and short circuits in low-voltage systems, with a relatively simple structure, and are commonly used in residential or commercial scenarios such as homes and offices.
In daily context, "circuit breaker" usually refers to small household circuit breakers (such as DZ47 series), while in the industrial field, "circuit breaker" is a broader concept that covers various types of protective switches.
2、 Comparison of structural design and arc extinguishing methods
The biggest difference in structure between circuit breakers and circuit breakers lies in the arc extinguishing medium, contact system, and type of release.
project
circuit breaker
Air circuit breaker (miniature circuit breaker)
The extinguishing medium can be air, oil, SF ₆ gas, or vacuum, and only air is used
The contact structure is mostly double break or rotating contacts, with strong arc extinguishing ability. Single break contacts have weaker arc extinguishing ability
The types of release devices, including thermal magnetic release, electronic release, intelligent release, etc., are basically thermal magnetic release (combination of thermal element and electromagnetic element)
Complex structure, suitable for industrial grade equipment with simple structure, modular design, and quick installation
Arc extinguishing medium: Circuit breakers can choose different arc extinguishing materials according to their application scenarios. For example, SF ₆ gas is suitable for high voltage environments, while air switches can only use air, so their arc extinguishing ability is limited in high current or high voltage environments.
Contact system: Circuit breakers often use double break or rotating contacts, which improves the breaking capacity and service life; The open circuit often adopts a single breakpoint structure, which is suitable for low current situations.
Release type: The circuit breaker is equipped with a variety of release types, which can adapt to different load characteristics and protection requirements; Air switches usually only use thermal magnetic release devices and cannot be finely adjusted.
3、 Comparison of Protection Function and Accuracy
1. Protection function of circuit breaker
Circuit breakers not only have basic overload protection and short-circuit protection, but also can achieve more complex protection functions through additional modules:
Leakage protection: By installing a residual current module (RCD) to detect residual current in the circuit, electric shock accidents caused by leakage can be prevented;
Ground fault protection: Identify and cut off the ground fault circuit;
Voltage protection: such as undervoltage and overvoltage protection, to prevent equipment from operating under abnormal voltage;
Remote control: Some circuit breakers support PLC linkage or remote opening and closing operations.
In addition, some electronic trip type circuit breakers can accurately set the operating current and response time, making them suitable for precision instruments or automation control systems that require high-precision protection.
2. Protection function of the circuit breaker
The function of the circuit breaker is relatively simple, mainly used for overload protection and short circuit protection:
Overload protection: using thermal elements to sense the magnitude of current, triggering a trip when the current exceeds the rated value for a certain period of time;
Short circuit protection: By inducing instantaneous high current through electromagnetic coils, the circuit is quickly cut off.
Due to its fixed tripping threshold range (such as C-type air switches suitable for lighting loads with small impulse currents, and D-type switches suitable for loads with large impulse currents such as motors), its protection accuracy is low and not suitable for situations sensitive to current fluctuations.
4、 Comparative analysis of applicable scenarios
1. Application scenarios of circuit breakers
Circuit breakers are widely used in the following fields due to their powerful functions and strong adaptability:
Industrial power distribution system: main control switches for equipment such as factory substations, large motors, transformers, etc;
High voltage/medium voltage power system: suitable for power grid systems with voltage levels of 10kV and above;
Special environmental applications:
Explosion proof locations (such as petroleum and chemical industries);
Equipment protection under harsh conditions such as high temperature, humidity, and vibration;
Data centers and communication base stations: scenarios that require high reliability and remote monitoring capabilities.
2. Application scenarios of empty switches
Due to its compact size, low cost, and easy installation, the air switch is mainly suitable for the following scenarios:
Home distribution box: used to control branch circuits such as lighting, sockets, air conditioning, etc;
Commercial building power distribution: such as low-voltage terminal power distribution systems in office buildings, shopping malls, schools, etc;
Small electrical protection: such as low-power equipment such as water pumps, fans, heaters, etc;
Temporary power supply system: such as temporary distribution boxes on construction sites, mobile power vehicles, etc.
5、 The difference between current and voltage levels
Circuit breakers can cover various current levels from households to industries, especially suitable for high load or high-voltage systems; However, air switches are only suitable for low voltage and low current applications and cannot meet the needs of large-scale industrial power distribution.
6、 Comparison of operating methods and maintenance costs
1. Operation and maintenance of circuit breakers
Operation method:
Manual operation (handle opening and closing);
Remote control (via electric motor mechanism or PLC control).
Maintenance requirements:
High end circuit breakers require regular inspection of the arc extinguishing chamber and contact wear;
Intelligent circuit breakers may require firmware updates or adjustments to protection parameters;
The maintenance cost is high, but the lifespan is long and the reliability is strong.
2. Operation and maintenance of empty switches
Operation method:
Manual operation is the main method (such as pulling the handle);
If remote control is required, an additional electric operation module needs to be installed.
Maintenance requirements:
Simple structure, no need for frequent maintenance;
When there is a malfunction, the entire module can usually be replaced directly;
Low cost, suitable for large-scale deployment.
7、 How to choose a circuit breaker or circuit breaker?
In practical applications, the selection of protective equipment should be comprehensively judged based on the following factors:
1. Look at the usage scenario
For the end branches of low-voltage distribution systems such as homes, shops, and offices, air switches should be given priority;
Circuit breakers should be selected for high load and high demand scenarios such as industrial distribution systems, large equipment, and substations.
2. Check the current and voltage levels
In situations with low current (≤ 100A) and low voltage (230V/400V), select the neutral switch;
Circuit breakers must be used in medium to high voltage and high current applications.
3. Check the functional requirements
If only basic overload and short circuit protection is needed and the budget is limited, choose an air switch;
If functions such as leakage protection, remote control, and voltage protection are required, circuit breakers should be selected.
4. Check maintenance and scalability
For systems that require long-term operation and high automation, circuit breakers are more suitable;
For temporary electricity and small distribution systems, air switches have a more cost-effective advantage.
8、 Clarification of Common Misconceptions
✅  Misconception 1: "Air circuit breaker is not a circuit breaker"
Misunderstanding: Many people believe that "circuit breakers" and "circuit breakers" are two completely different devices.
Correct explanation: Air circuit breaker is a type of circuit breaker and belongs to its subclass. Circuit breaker is a broad concept that includes various forms such as molded case circuit breakers, frame circuit breakers, miniature circuit breakers (i.e. circuit breakers), etc.
✅  Misconception 2: "Circuit breakers are definitely more expensive than circuit breakers"
One sided understanding: believing that any circuit breaker is more expensive than an air circuit breaker.
Actual situation: Small circuit breakers are essentially circuit breakers, and their prices are not high; And high-end industrial circuit breakers (such as models with leakage protection and remote control functions) are much more expensive than ordinary circuit breakers.