Introduction
When it comes to handling high-voltage electrical systems, an air blast circuit breaker is a reliable choice. This type of breaker is used to protect circuits from sudden overflow of power by utilizing compressed air. Unlike traditional breakers, which rely on oil or vacuum, this construction ensures quicker operation and better arc extinction.
What is an Air Blast Circuit Breaker?
An air blast circuit breaker is a special type of device used to handle high-voltage systems. It follows a simple principle, where compressed air is applied to force the arc extinction, preventing an overflow of electric current. Inside, there is a fixed contact and a moving contact, which separate under pressure to stop the flow of electrical energy and avoid damage to the circuit. You can also read miniature circuit breaker.
Air Blast Circuit Breaker symbol
Construction of Air Blast Circuit Breaker
Air Reservoir
Hollow Insulator Assembly
Arc Extinction Chamber
Valves
Current Carrying Conductors
Air Reservoir
The construction of an air blast circuit breaker involves several key parts that work together to control and protect high-voltage systems. A reservoir stores compressed air at high pressure, usually around 20-30 atm, which is essential for arc extinction. This air is supplied through an auxiliary system that keeps the circuit functioning smoothly.
Hollow Insulator Assembly
Insulators play a crucial role as they protect the equipment and insulate different parts from high voltage. The hollow insulator assembly connects the reservoirs to the arc extinction chamber and ensures the flow of air in the right direction.
Valves
Valves located at the base of the insulators regulate this flow, preventing any sudden faults in the system.
Arc Extinction Chamber
Inside the arc extinction chamber, the circuit breaks and interrupts the current. This chamber consists of moving and fixed contacts, where air pressure forces the contacts apart to stop the arc. The movement of these contacts is dependent on the pneumatic operating system, which ensures efficient operation.
current-carrying conductors
The current-carrying conductors link all neighboring equipment in series, making sure the circuit remains stable. If a faulty circuit is detected, the valves quickly open with the help of an iron rod, allowing compressed air to extinguish the arc and restore safety. You can also read oil circuit breakers.
Working of Air Blast Circuit Breaker
Under normal conditions, the breaker remains closed, and the contacts inside the arc extinction chamber stay in touch. However, when a faulty circuit occurs, the valves quickly open, allowing compressed air to enter the chamber through a hollow setup. The sudden rise in pressure increases the force on the moving contact, causing its separation from the fixed contact.
As the contacts separate, an arc is created due to ionization of the air, but it is rapidly extinguished as the ionized air exits through the outlet. Once the fault is cleared, the pressure drops, and the valves close, ensuring the circuit is fully broken and safe to operate again. You can also read minimum oil circuit breakers.
Types of Air Blast Circuit Breakers
- Axial Blast Air Circuit Breaker
- Cross Blast Air Circuit Breaker
- Radial Blast Air Circuit Breaker
Axial Blast Air Circuit Breaker
In this type of breaker, air flows axially through the arc chamber to quickly interrupt faults. Under normal conditions, the moving and fixed contacts remain touching, held together by a spring. However, when a fault situation occurs, high-pressure air enters, forcing the nozzle to open and allowing the arc to form.
As the arc extends, the pressure increases, causing the arc to stretch in length and lower its temperature. This raises the arc voltage beyond what the system can sustain, leading to its extinction. The tip of the nozzle helps direct the air, while the spring is deforming under force, ensuring a complete break in the circuit.
Cross Blast Air Circuit Breaker
This type of circuit breaker uses a blast pipe positioned perpendicular to the arc chamber. When the moving contact withdraws from the fixed contact, an arc is established, and high-pressure air enters through the gap. The air flows directly across the arc, pushing it toward the exhaust side for quick cooling.
As the arc extends, the air movement helps in rapid quenching, leading to effective arc extinction. The alignment of the pipe and chamber ensures that the arc is driven in the opposite direction, preventing re-striking. This design leads to faster operation, making it a valuable position in high-voltage circuit protection.
Radial Blast Air Circuit Breaker
This circuit breaker follows the double blast principle, where air is admitted radially into the fixed and moving contacts inside the arc chamber. The flow of air in the arcing region is axial, meaning it moves along the direction of arc formation, ensuring quick arc extinction. This method improves the breaker’s efficiency by handling high-voltage faults effectively.
One major advantage is its ability to use resistance switching, which leads to a reduction in transient overvoltages in the system. The increased number of arc brakes allows for better control over the fault, ensuring extra safety. By effectively managing power surges, this breaker prevents damage to electrical networks and enhances system stability.
Advantages of Air Blast Circuit Breakers
Cost-effective and readily available in the market, they make a practical choice for high-voltage systems.
The equipment is chemically stable, ensuring long-term reliability and resistance to environmental changes.
The chance of a fire hazard is completely eliminated, making it safer than traditional circuit breakers.
Consistent arcing at short time intervals reduces the burning of contact valves, leading to improved durability.
Designed to work efficiently with high voltages at higher speeds, ensuring quick fault clearance.
A sustainable system with a low cost of maintenance reduces operational expenses over time.
Disadvantages of Air Blast Circuit Breakers
Compressed air must be available at all times, requiring a complex installation and continuous monitoring.
The largest plant setups need two or more compressors, making the system expensive to maintain.
Leakage in the pipe fittings is a common problem, reducing system efficiency and reliability.
Maintenance is costly due to the high-pressure circuit design and frequent servicing needs.
When compared to oil or air-brake systems, it is less efficient in low-voltage applications.
External factors like weather and dust can affect performance, making it harder to operate smoothly.
Applications of Air Blast Circuit Breakers
Used to protect machines in industrial setups and major power stations from electrical faults.
Essential for operating high-voltage systems, like transformers, capacitors, and AC and DC generators.
Helps control transient overvoltages, ensuring stable performance in large power networks.
The arc chamber design helps increase resistance, making it efficient in handling high-energy faults.
Can also function as fire extinguishers in electrical setups, adding an extra layer of safety.
Conclusion
Air blast circuit breakers are an essential part of high-voltage power systems, providing fast and efficient arc extinction using compressed air. They have advantages like being cost-effective, easy to maintain, and fast. This makes them a dependable option for power stations and industrial uses. But they have challenges too. These include high installation costs, air leaks, and tricky maintenance.
Air blast circuit breakers have some downsides, but they are still popular. They protect important electrical gear like transformers, capacitors, and generators. They also help manage sudden overvoltages. Thanks to technology, efficiency and design keep getting better. This boosts their performance and makes them a smart choice for today’s electrical networks.
