📘 Air Blast Circuit Breaker (ABCB) – Construction, Working & Types
Air Blast Circuit Breaker uses high-pressure compressed air as arc quenching medium. It was widely used in high voltage transmission systems.
🔹 1️⃣ Basic Working Principle
- Under normal condition → Contacts closed
- Fault occurs → Relay sends trip signal
- Contacts separate → Arc forms
- High-pressure air blast is directed across arc
- Arc cools and de-ionizes
- Arc extinguishes at natural current zero
High-pressure air removes ionized particles and interrupts the arc.
🔹 2️⃣ Types of Air Blast Circuit Breakers
- Axial Blast Type: Air flows along arc path
- Cross Blast Type: Air flows perpendicular to arc
- Radial Blast Type: Air flows radially outward
🔹 3️⃣ Construction
- Fixed Contact
- Moving Contact
- Air Compressor
- Air Reservoir Tank
- Nozzle Arrangement
- Control Valves
Air pressure used: 20 – 30 bar
🔹 4️⃣ Advantages
- Very fast arc extinction
- Suitable for frequent switching
- No fire hazard
- High-speed reclosing possible
🔹 5️⃣ Disadvantages
- Requires air compressor system
- High maintenance
- Noisy operation
- Less compact compared to SF₆
🔹 6️⃣ Comparison with Other Breakers
| Type | Voltage Level | Maintenance | Arc Medium |
|---|---|---|---|
| Air Blast | High Voltage | High | Compressed Air |
| SF₆ | Extra High Voltage | Medium | SF₆ Gas |
| Vacuum | Medium Voltage | Low | Vacuum |
🎯 GATE Important Points
- Arc extinguished by compressed air blast
- Used in older HV transmission systems
- Requires air compressor arrangement
- Faster dielectric recovery than oil CB
Air Blast Circuit Breaker = High-Speed HV Protection (Older Technology)
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