 Table of Contents

1. Introduction
2. Historical Evolution of Circuit Breakers
3. Oil Circuit Breakers
4. Air Circuit Breakers
5. SF6 Gas Circuit Breakers
6. Vacuum Circuit Breakers
7. Comparative Analysis of Breaker Properties
8. Technical Data from Manufacturers & Quality Analysis
9. Conclusion
10.Reference
1. Introduction

The power industry is experiencing significant advancements with an increasing need for circuit breakers that
ensure network safety and continuity of power supply in various voltage systems. Choosing the appropriate type
of circuit breaker improves operational efficiency, reduces costs, and ensures fast tripping and safe operation in
the event of faults or failures. This article will review and compare four main types of circuit breakers: Oil
Circuit Breakers, Air Circuit Breakers, SF6 Gas Circuit Breakers, and Vacuum Circuit Breakers, with a focus
on performance metrics such as efficiency, tripping speed, operational safety, and cost.

2. Historical Evolution of Circuit Breakers

 Oil Circuit Breakers (OCB) were among the earliest types, introduced in the early 20th century. Widely
used in medium voltage networks.
 Air Circuit Breakers (ACB) appeared later, offering a simpler and eco-friendly solution for low voltage
systems.
 SF6 Circuit Breakers emerged in the 1950s, revolutionizing high voltage applications with compact designs
and high reliability.
 Vacuum Circuit Breakers (VCB) were developed in the 1960s, offering maintenance-free operation and
high endurance for medium voltage applications.
3. Oil Circuit Breakers

Oil circuit breakers are used in numerous applications, especially in medium voltage systems, due to their
ability to handle high current flows and provide effective protection through a tripping mechanism that relies on
oil insulation.

2.1 Characteristics and Advantages

 Tripping Mechanism: Uses oil as an insulating medium to quench the electrical arc during the tripping
process, allowing reliable separation of the current.
 Endurance: Known for their ability to withstand high short-circuit currents under specific conditions,
with the breaking capacity defined by strict standards.
 Reliability: Despite the vast variety of operating modes, manufacturer-provided data helps to accurately
determine the actual performance of circuit breakers under specific conditions.

2.2 Disadvantages and Challenges

 Maintenance and Wear: Requires periodic maintenance and careful inspections to ensure the oil's
characteristics do not deteriorate over time.
 Environmental Risks: In case of leakage, oil can pose an environmental risk to water bodies and the
air, requiring preventive measures to minimize damage.
 Variable Performance: The breaker's ability to properly separate the current depends on several factors
such as operating voltage and general system conditions.

2.3 Suitable Applications

Oil circuit breakers are typically used in electrical substations and medium voltage distribution systems, where
the need for tripping and the ability to handle high currents are essential. These are suitable for applications
where the total cost and technical capabilities allow for the deployment of precise and reliable solutions.
4. Air Circuit Breakers

Air circuit breakers are a preferred option in low voltage applications due to their simplicity and efficiency in
basic protection applications. They rely on air as an insulating medium to quench the electrical arc, making
them more environmentally friendly.

3.1 Characteristics and Advantages

 Tripping Mechanism: Provides rapid separation of the current through air, allowing quick
disconnection in emergency situations with medium speed.
 Safety: Air is a non-polluting medium and does not pose environmental risks, providing safety benefits
in certain applications.
 Simplicity: Air circuit breakers have a less complex design compared to oil or SF6 gas systems, which
makes maintenance and regular operation easier.

3.2 Disadvantages and Challenges

 Tripping Speed: The tripping speed may be slower compared to other types, making them less suitable
for applications that require very fast current separation.
 Efficiency: Air circuit breakers may suffer from lower efficiency when dealing with high currents or
unstable operating conditions.
 Application Limits: These breakers are primarily used in low voltage systems and may not be suitable
for high or medium voltage systems due to design limitations.

3.3 Suitable Applications

Air circuit breakers are widely used in low-voltage residential and industrial electrical systems, where they
provide sufficient protection and good operational continuity in environments that do not require exceptionally
fast tripping speeds or handling of very high currents.
5. SF6 Gas Circuit Breakers

SF6 gas is one of the most widely used insulating materials in high voltage circuit breakers due to its superior
insulating properties and its ability to quench electrical arcs rapidly. SF6 gas circuit breakers rely on the gas’s
properties to ensure safe and effective tripping.

4.1 Characteristics and Advantages

 Tripping Mechanism: SF6 gas acts as an excellent insulator for electrical arcs, enabling rapid and safe
disconnection of the electrical current.
 High Voltage Handling: Primarily used in high voltage circuit breakers where effective and rapid
insulation is crucial.
 Thermal and Electrical Stability: SF6 provides stable and effective performance under different
operating conditions compared to other insulation mediums.

4.2 Disadvantages and Challenges

 Environmental Risks: SF6 gas is a potent greenhouse gas with a high environmental impact,
necessitating environmentally friendly handling and disposal practices.
 Chemical Decomposition: SF6 can decompose under electrical arc conditions, producing byproducts
such as CF4 and other compounds that may negatively affect the system.
 Cost: Although highly effective, operational and maintenance costs may increase due to the need to
regularly replenish the gas and ensure proper disposal.

4.3 Suitable Applications

SF6 gas circuit breakers are mainly used in high voltage systems, such as long-distance transmission networks
and substations, where rapid and reliable tripping is essential. The exceptional properties of SF6 make it a
preferred choice in densely packed environments for arc quenching.
6. Vacuum Circuit Breakers

Vacuum circuit breakers are a modern solution for providing effective protection in medium and high voltage
systems, relying on advanced techniques to achieve fast and accurate tripping without the need for traditional
insulating media.

5.1 Characteristics and Advantages

 Tripping Mechanism: Vacuum circuit breakers quench the arc in a sealed chamber filled with vacuum,
allowing for extremely fast tripping while reducing the chances of contaminant formation.
 Low Maintenance: With no fluids or gases that can decompose, vacuum circuit breakers have low long-
term maintenance costs.
 Compact Design: These breakers often feature a compact and lightweight design, allowing for use in
equipment with limited space and offering high performance in terms of tripping speed.

5.2 Disadvantages and Challenges

 Initial Costs: Despite low operational costs, vacuum circuit breakers require high initial investment in
equipment and materials.
 Technological Demands: Designing and maintaining vacuum circuit breakers requires high precision
and the use of multiple physics models to ensure optimal performance, adding complexity to
engineering processes.
 Sensitivity to Operating Conditions: The breaker’s performance can be sensitive to operating
conditions, and slight changes in the environment may lead to noticeable variations in tripping time and
arc quenching efficiency.

5.3 Suitable Applications

Vacuum circuit breakers are used in industrial and commercial applications requiring high reliability and fast
tripping speeds, particularly in environments where equipment space is limited. They are also applied in
transmission systems and setups requiring quick changes in electrical current.
7. Comparative Analysis of Circuit Breaker Characteristics
This section provides a detailed comparison of the four main types of circuit breakers based on technical aspects
and key performance criteria, assisting in selecting the most suitable breaker for each practical application.

7.1 Comparative Table of Circuit Breaker Characteristics

SF6 Gas Circuit Vacuum Circuit

Feature Oil Circuit Breakers Air Circuit Breakers
Breakers Breakers
Uses oil as an Uses SF6 gas for
Interruption Uses air to quench the Arc quenched in a
insulating medium to insulation and arc
Mechanism arc sealed vacuum chamber
extinguish the arc extinction
Breaking
Medium to High Medium Very High Very High
Speed
Dependent on Excellent Exceptional
Operational Environmentally safe
preventive performance with performance with low
Safety but may lag in speed
maintenance environmental risks operational risk
Relatively high
High operational and High initial investment,
Cost maintenance and Low initial cost
maintenance cost but low operating cost
operation cost
Industrial and
Low voltage
Typical Medium voltage High voltage systems commercial systems
residential and
Applications systems and substations with high performance
industrial systems
demands

Table 1: Comprehensive comparison of various types of circuit breakers

Detailed Comparison Table

Feature Oil CB Air CB SF6 CB Vacuum CB

Rated Voltage (kV) Up to 72.5 Up to 15 Up to 800 Up to 72.5

Rated Current (A) Up to 2000 Up to 6300 Up to 4000 Up to 4000

Breaking Time (ms) 50-100 30-60 20-50 20-40

Reliability Moderat Moderate High Very High

Maintenance Cycle 1-2 years 2-5 years 5-10 years 10-20 years

Impact Oil disposal issues Eco-friendly High GWP gas Eco-friendly

8.Technical Data from Manufacturers
ABB (2025 Catalog) SF6 CBs rated up to 145 kV with breaking capacity of 40 kA.

Vacuum CBs up to 40.5 kV, 31.5 kA, with mechanical endurance of 30,000 operations.

Siemens (2025 Catalog) SF6 CBs up to 800 kV, 63 kA breaking capacity.

Air CBs in LV systems rated up to 6300 A, widely used in Sentron series.

Schneider Electric (2025 Catalog) Vacuum CBs with up to 30,000 operations and embedded sensors.

SF6 CBs in their GHA series with remote monitoring and diagnostics.

8.1 Qualitative Analysis

 Oil Circuit Breakers: Offer high capability to handle large currents but require frequent and precise
maintenance. Oil leakage poses an environmental risk, making them more suitable for systems with
robust maintenance resources.
 Air Circuit Breakers: An ideal choice for low voltage systems thanks to their simplicity and
environmental safety, though their medium breaking speed may not meet the demands of critical
systems.
 SF6 Gas Circuit Breakers: Deliver superior performance in high voltage systems with excellent
breaking speed, but the high cost and environmental impact of the gas limit their use in eco-sensitive
projects.
 Vacuum Circuit Breakers: Represent the best solution for advanced industrial and commercial
applications due to their high speed, efficiency, and minimal maintenance needs. However, they come
with a higher upfront cost and require precise design and
 operation.

8.2 Applications

Type Applications

Oil---- Older substations, rural medium voltage networks

Air---- Low voltage switchgear, industrial panels

SF6--- High voltage transmission, GIS substations

Vacuum------- Medium voltage industries, wind farms

9.Conclusion
This study highlights the critical importance of selecting the appropriate type of circuit breaker based on the
technical, economic, and environmental requirements of the electrical system. Four main categories of circuit
breakers were reviewed:

 Oil Circuit Breakers: Suitable for medium voltage applications with the advantage of handling high
fault currents, though they require regular maintenance and may pose environmental risks.
 Air Circuit Breakers: Provide simple and environmentally safe solutions for low voltage systems,
although their breaking speed may be limited in certain critical applications.
 SF6 Gas Circuit Breakers: Known for their high breaking speed and excellent efficiency in high
voltage systems, yet the operational costs and environmental concerns present significant challenges.
 Vacuum Circuit Breakers: Represent the optimal choice for applications requiring ultra-fast
interruption and high operational efficiency with minimal maintenance, though they demand higher
initial investment and advanced design technologies.

Key Findings:

 Establishing key selection criteria among different types of circuit breakers includes voltage level,
breaking speed, operational safety, and cost.
 Comparative tables and analyses show that each breaker type has its own advantages and disadvantages,
which necessitates comprehensive evaluation before making a decision.
 The decision-making flowchart offers a practical framework to determine the most suitable type based
on the specific system requirements.
 Vacuum and SF6 gas circuit breakers deliver outstanding operational performance in high voltage
systems, while air circuit breakers remain ideal for low voltage applications due to their simplicity and
lower cost.
 Regular maintenance and environmental safety measures are major factors affecting the effectiveness of
oil and gas circuit breakers.

Through this study, it becomes clear that selecting the right circuit breaker is not merely a technical decision but
requires a holistic vision that considers operational, financial, and environmental demands of each system.
Accordingly, engineers and decision-makers should thoroughly evaluate all technical standards and influencing
factors before adopting any circuit breaker type to ensure the sustainability of the electrical network and to
achieve the highest levels of safety and efficiency.
10.References
1. IEEE Std C37.010-2016 - IEEE Application Guide for AC High-Voltage Circuit Breakers Rated on a
Symmetrical Current Basis.
2. IEC 62271-100:2017 - High-voltage switchgear and controlgear - Part 100: Alternating-current circuit-
breakers.
3. Singh, M. (2020). High Voltage Engineering. New Delhi: McGraw-Hill Education.
4. Kasztenny, B., & McLaren, P. (2005). "SF6 Gas Circuit Breakers: Design, Performance, and
Environmental Concerns." IEEE Transactions on Power Delivery, 20(3), 1491-1498.
5. Greenwood, A. (1996). Electrical Transients in Power Systems. 2nd ed. Wiley-IEEE Press.
6. Abdel-Salam, M., et al. (2000). High Voltage Engineering: Theory and Practice. Marcel Dekker Inc.
7. ABB Switchgear Manual (2021 Edition). Zurich: ABB Group.
8. Siemens Technical Guide (2022). Circuit Breaker Types and Applications. Siemens AG.