Load break switches (LBSs) belong to the important categories of modern equipment, commonly used in medium- and high-voltage distribution networks. Since Load break switches have primary functions of switching and safe operation under live load conditions, then establishing their importance in grid stability and equipment maintenance. This article attempts to present an overview of the meaning, working principles, various types, and applied value of load switches. These devices are also known as load interrupters, highlighting their essential role in interrupting load currents safely.
What is a Load Break Switch?
A load break switch is a type of switchgear that can safely disconnect a circuit under load conditions. It is mainly used in medium-voltage or high-voltage power systems. It has combined switching and isolation functions and is typically used for controlling power supply feeders, transformer input/output lines, or feeder lines. Compared to circuit breakers, load switches have a simpler structure and lower costs, but they provide reliable disconnection capabilities in medium-current switching scenarios. These devices are quite popular in electric isolation and control applications within distribution systems. Such switches are sometimes referred to as load break interrupter switches in technical literature.
What is the Purpose of a Load Break Switch?
A load break switch serves four key functions:
Circuit Isolation: Safely separates sections of a power system (e.g., transformers, feeders) for maintenance, protecting workers from live electricity.
Load Transfer: Enables smooth switching between power sources (e.g., main grid to backup generator) without downtime or equipment damage.
Minor Overload Handling: While not for severe faults, some LBS manage small overloads to prevent system strain.
System Control: Lets operators turn circuits on/off to optimize efficiency or respond to demand changes.
Load Break Switch Working Principle
A load break switch is primarily used for the closing and opening of a circuit under energized conditions and while carrying a certain load current. The working of a load break switch involves the use of a special arc-extinguishing device for rapidly opening contacts and effectively extinguishing the arc during the breaking process. This prevents the arc from damaging the equipment. Different load break switches (vacuum, air, SF6, etc.) have different types of media or structures used for extinguishing the arc. To operate, a switch device is manually or electrically actuated to perform closing or opening movements for safe and uninterrupted operation and maintenance of the power grid.
Types of Load Break Switch
Depending on the operating environment, voltage level, and function, load break switches can be classified into various types. The following is a detailed classification:
Features: Handles medium-voltage challenges (higher current, arc energy) with options for vacuum, air, or SF6 quenching. Often includes visible break contacts for safety.
Applications: Medium-voltage grids, factories, commercial buildings, and renewable energy setups (solar/wind).
Features: Robust construction to withstand high electrical stress, often using SF6 for arc quenching. Includes safety interlocks and enhanced insulation.
Applications: High-voltage transmission, power stations, and large industrial complexes.
Air Load Break Switch
Relies on ambient or compressed air for arc quenching.
Features: Simple, cost-effective design but requires more maintenance (contacts exposed to dirt/corrosion).
Voltage Range: Up to 36 kV (low to medium voltage).
Applications: Outdoor setups like overhead lines and rural grids where cost matters most.
Uses SF6 gas for arc quenching, prized for high performance.
Features: Superior arc extinction, compact design, and weather resistance. Note: SF6 is a potent greenhouse gas, requiring careful handling and recycling.
Voltage Range: 1 kV to 245 kV+.
Applications: Indoor/outdoor switchgear, transmission networks, and industrial facilities needing reliability.
Type of Load Break Switch
Arc-Quenching Medium
Voltage Range
Key Features
Common Applications
Vacuum Load Break Switch
Vacuum
Up to 36 kV
Fast quenching, long life, low maintenance
Indoor substations, industrial setups
Medium Voltage Load Break Switch
Vacuum/air/SF6
1 kV–36 kV
Versatile, visible breaks
Medium grids, factories, renewables
High Voltage Load Break Switch
SF6 (common)
Above 36 kV
Robust, safety-focused
High-voltage transmission, power stations
Air Load Break Switch
Air
Up to 36 kV
Affordable, simple
Outdoor/rural grids
SF6 Load Break Switch
SF6
1 kV–245 kV+
High performance, compact
Switchgear, industrial facilities
Load Break Switch Advantages
Load break switches offer several significant advantages and are suitable for use in a variety of power distribution systems. First, they support safe live switching, ensuring the safety of operators and equipment. Their high reliability ensures long-term stable operation and reduces the risk of failure. Compared to other devices, load switches have a simpler structure, enabling cost-effective system configuration. At the same time, they are easy to maintain, reducing operational costs. Thanks to its flexible design, the load switch offers flexible operation and easy installation, making it easy to deploy even in environments with limited space. Furthermore, its excellent environmental adaptability allows it to perform exceptionally well in high-temperature, high-humidity, or dusty environments, making it an ideal choice for modern distribution systems.
Power Distribution: Isolates feeders/transformers in primary/secondary networks for repairs.
Industrial Facilities: Controls machinery and production lines, allowing section-specific shutdowns.
Commercial Buildings: Manages power to floors or systems (lighting, HVAC) in offices, malls, and hospitals.
Renewables: Connects/disconnects solar farms or wind turbines from the grid.
Substations: Integral to switchgear, isolating equipment like transformers.
Mining: Withstands harsh conditions to power mining machinery.
Railways: Controls power to tracks and signals, ensuring safe operations.
Load Break Switches Maintenance
Proper maintenance ensures longevity and safety:
Visual Inspections: Check for damage, corrosion, or loose connections (per manufacturer schedules).
Contact Care: Clean contacts to prevent resistance/overheating; lubricate moving parts with recommended oils.
Arc-Quenching Checks: For SF6 switches, monitor gas pressure and fix leaks. For vacuum switches, inspect chambers for cracks.
Operation Tests: Verify smooth opening/closing (manual and remote). Use tools to confirm proper arc quenching.
Insulation Tests: Measure resistance to detect degradation.
Record-Keeping: Track inspections, repairs, and issues to plan maintenance.
Compliance: Follow manufacturer guidelines and industry standards.
Conclusion
In summary, load switches are key devices in power distribution systems. Not only do they have reliable breaking capabilities, but their diverse types (such as vacuum, SF6, air, etc.) make them suitable for different voltage levels and application scenarios. Chuanli focuses on the design, development, and production of premium load switches, ensuring that clients receive dependable and safe power systems. For more information on our products and their technical merits, as well as to select a dependable load break switch manufacturer, browse the Chuanli official webpage.