Research on Application of 10kV Load Switchgear in Distribution Networks

As a frontline worker in power distribution operation and maintenance, I deal with load switches daily—they’re the “gatekeepers” of medium - voltage distribution systems, ensuring stable power supply for users. With rapid economic development, the demand for power system safety and reliability keeps rising. Medium - voltage distribution systems are crucial for grid stability, and load switches (as key line - mounted equipment) play a pivotal role. Their main functions include: ① Closing load currents of distribution main and branch lines during maintenance or load transfer; ② Creating visible break points for personnel safety during line repairs; ③ Assisting in grounding for maintenance. Beyond functionality, they must also be easy to install, reliable in operation, low - maintenance, and cost - effective.

Load switches are switchgear with simple arc - extinguishing devices. Structurally, they must meet: visible gaps in the open position (eliminating the need for series - connected disconnectors); high endurance for switching operations without frequent contact/arc - chamber maintenance; and the ability to close short - circuit currents (meeting dynamic/thermal stability requirements, even if they don’t open short - circuit currents).

1. Classification and Comparison of Load Switches
1.1 Classification by Arc - Extinguishing Medium

Load switches are categorized into five types based on arc - extinguishing media: mineral oil, compressed air, organic - material gas - producing, SF₆ gas, and vacuum load switches. Functionally, they include general - purpose, special - purpose, and specific - application types (e.g., motor - operated, disconnector - backed capacitor - bank, frequent - operation, and back - to - back switches).

1.2 Technological Evolution and Advantages of Vacuum Load Switches

With technological advancements, traditional load switches (mineral oil, compressed air, gas - producing) are being replaced by SF₆ and vacuum load switches—especially the latter, which are now widely used. Tests show vacuum switches outperform traditional types in many aspects:

• Fast Arc Extinguishing: Vacuum arcs extinguish at current zero (due to metal vapor diffusion), with insulation recovery faster than in air or SF₆. Ideal for switching no - load transformers, cables, and overhead lines.

• Safe and Clean: Arcs don’t splash, preventing contamination/damage to cabinet components.

• Long Lifespan: Smaller arcing distance, lower arc voltage, and less contact wear mean more switching cycles and minimal maintenance.

• Efficient Operation: Low closing energy for the operating mechanism, simple structure, and easy miniaturization.

• Stable Contact Resistance: No oxidation in a vacuum, ensuring long - term low contact resistance.

2. A New Type of Combined Isolation Load Switch
2.1 Limitations of Traditional Configurations

Conventional load switches have arc - extinguishing devices in series with the main circuit. Their dynamic/thermal stability is limited by arc - chamber design/materials, making them unsuitable for large - capacity systems. Pairing them with disconnectors adds complexity: cumbersome maintenance, slow recovery, frequent upkeep, and high initial costs.

2.2 Introduction to the Fla15/97 Combined Isolation Load Switch

The Fla15/97 outdoor combined isolation load switch addresses these issues and is widely used in European grids.

2.2.1 Main Functions

It integrates the functions of a vacuum load switch, disconnector, and grounding switch—an optimized, multi - functional device balancing technical performance and economic efficiency.

2.2.2 Product Features

• Comprehensive and Advanced: The vacuum arc chamber only handles circuit switching (no load/short - circuit current in the closed position). Fast insulation recovery, minimal contact wear, long lifespan, low contact resistance, and no arc damage to main contacts. Short operating stroke, compatible with small actuators.

• Easy Installation and Maintenance: Interlocked operation between the vacuum switch and disconnector enables one - step opening/closing, preventing misoperations.

• Low Maintenance: Simple structure with a vacuum arc chamber lifespan of 5,000 operations and other components lasting 30,000 operations. The built - in actuator uses patented technology from Germany’s Drees.

2.2.3 Technical Highlights

• Innovative Switching Design: Series - parallel switching of vacuum arc chambers (auxiliary arc - extinguishing system) ensures no arc impact on main contacts.

• Built - in Insulated Actuator: Clear separation between main and auxiliary contacts, with faster insulation recovery after opening.

• Reliable Insulation: Copper tension bands maintain insulation distances.

• Compact Operation: Short stroke, compatible with small actuators.

• Long Electrical Lifespan: Minimal main contact wear.

3. Conclusion

As the power industry expands to meet rapid economic growth, distribution networks need simple, reliable, safe, and cost - effective solutions. Traditional “circuit breaker + disconnector” or “drop - out fuse” configurations only partially meet these needs. Outdoor isolation load switches (like the Fla15/97) offer a better balance of functionality and economy.

Data shows load switches are used 10 times more than circuit breakers for distribution line branches in Europe and America. By integrating with other technologies, they’re also widely applied in urban distribution networks (e.g., ring main units, cable branches, and customer service lines).

For frontline operators like me, promoting such advanced equipment isn’t just about technical upgrades—it’s about ensuring grid stability, reducing maintenance burdens, and delivering reliable power to users. As distribution networks evolve, these smart, efficient load switches will become even more indispensable.