Types of Circuit Breaker with Detailed Classifications | TheElectricalGuy

Summary

This video explains the crucial role of circuit breakers in electrical systems, covering their definition, classification, and evolution. It details how circuit breakers operate under both normal and abnormal conditions, such as short circuits. The video categorizes circuit breakers based on voltage class, installation type, external design, and interrupting medium (e.g., air, oil, SF6, vacuum). It also highlights current trends, with SF6 circuit breakers dominating the high-voltage market and vacuum breakers being preferred for lower-voltage applications. The video provides valuable insights into the history, technology, and future of circuit breakers in modern electrical engineering.

Takeaways

• 😀 A circuit breaker is a mechanical device designed to make, carry, and break currents under normal and abnormal conditions, such as short circuits.
• 😀 The definition of a circuit breaker can be split into two parts: normal conditions (making, carrying, and breaking current) and abnormal conditions (carrying short-circuit currents temporarily and breaking them).
• 😀 Circuit breakers can be classified by voltage class: low voltage (up to 1000 V) and high voltage (above 1000 V, typically up to 800 kV).
• 😀 Circuit breakers can be installed indoors or outdoors. Indoor breakers are used in controlled environments, while outdoor breakers are used in exposed conditions, typically above 72.5 kV.
• 😀 External design of circuit breakers includes **live tank breakers** (interrupting unit at live potential) and **dead tank breakers** (interrupting unit at grounded potential), with the latter being more compact and safer.
• 😀 The interrupting medium in circuit breakers has evolved from air to oil to SF6 gas, with SF6 gas currently being the dominant choice due to its superior arc-quenching properties.
• 😀 **SF6 circuit breakers** are used for high-voltage systems (above 36 kV), while **vacuum circuit breakers** are used for low to medium voltage systems (up to 36 kV).
• 😀 Air blast and oil circuit breakers have been phased out due to safety concerns and inefficiency in interrupting faults.
• 😀 **SF6-free** technologies are emerging, driven by environmental concerns over SF6 gas, with future developments focusing on more sustainable solutions.
• 😀 Understanding the classification of circuit breakers helps in choosing the appropriate breaker for specific voltage levels, installation types, and interrupting mediums, ensuring system protection and efficiency.

Q & A

What is the definition of a circuit breaker?

A circuit breaker is a mechanical device capable of making, carrying, and breaking currents under normal circuit conditions, and making, carrying for a specific time, and breaking currents under abnormal conditions like short circuits.

How can the definition of a circuit breaker be simplified?

The definition can be split into two parts: (1) under normal conditions, it can make, carry, and break the current; (2) under abnormal conditions, it can carry high fault currents for a specific time and break them under short circuit conditions.

How are circuit breakers classified based on voltage?

Circuit breakers are classified into two main categories: low voltage circuit breakers (up to 1000V) and high voltage circuit breakers (from 1000V up to 800kV). Further sub-categories can include medium voltage and transmission voltage levels.

What are the key differences between indoor and outdoor circuit breakers?

Indoor circuit breakers are designed for use inside a building with controlled environmental conditions, whereas outdoor circuit breakers are installed outside and exposed to natural elements. The main difference is the type of enclosure used.

What is the distinction between live tank and dead tank circuit breakers?

In a live tank circuit breaker, the interrupter portion is at the live potential, while in a dead tank circuit breaker, the interrupter is inside a metal tank at dead potential. This design difference affects safety and electrical isolation.

Why are dead tank circuit breakers considered more compact than live tank breakers?

Dead tank circuit breakers are more compact because the interrupter is enclosed in a metal tank, allowing for a smaller design while maintaining electrical isolation and safety.

What are the types of interrupting mediums used in circuit breakers?

Circuit breakers use various interrupting mediums including air, oil, SF6 gas, and vacuum. Initially, air and oil were used, but these have been replaced by SF6 and vacuum technology due to better performance and higher current-breaking capabilities.

What are the advantages of SF6 gas in circuit breakers?

SF6 gas is an excellent interrupting and arc-cooling medium. It provides superior performance compared to air and oil, allowing for higher voltage and current breaking capacities. SF6 circuit breakers dominate the market for high voltage applications.

Why is vacuum technology superior to SF6 in certain cases?

Vacuum circuit breakers are considered superior to SF6 because they have a lower environmental impact and are capable of interrupting currents more efficiently. However, they are mainly used for voltages up to 36kV, whereas SF6 is used for higher voltage levels.

What types of circuit breakers are currently in use in the industry?

Currently, SF6 and vacuum circuit breakers are the most commonly used in the industry. Other types, such as air blast and oil circuit breakers, have become obsolete due to their limitations in performance.