What are pole-mounted vacuum circuit breakers and load switches?

Pole-mounted vacuum circuit breakers and pole-mounted vacuum load switches are the two most common types of switching equipment in power distribution networks (especially at the 10kV voltage level). Both are installed on utility poles, and their core arc-extinguishing medium is vacuum, but their functions and applications differ fundamentally.

Below, I will provide a detailed comparison and explanation of them from multiple perspectives.

Key Conclusions at a Glance:

 

Vacuum Circuit Breaker: A protective device. It interrupts fault currents (such as short-circuit currents), acting like an "automatic fuse" on a circuit, integrating control, protection, and isolation functions.

Vacuum Load Switch: An operating device. It can only interrupt normal load currents, not fault currents. It is mainly used for circuit switching operations and has a relatively simple function.

 

Detailed comparison

Features	Pole-mounted vacuum circuit breaker	Pole-mounted vacuum load switch
Core Functions	Breakdown and protection	Isolation and switching
Current Breaking Capacity	Capable of breaking rated load current and rated short-circuit current	Can only interrupt rated load current and specified transfer current
Protection Functions	Integrated (through internal intelligent protection controller, achieving overcurrent, instantaneous trip, zero-sequence, etc.)	Not self-operated; requires a fuse to provide protection.
Structural Complexity	High (integrated operating mechanism, current transformer, protection controller, etc.)	Low (usually spring-operated or electromagnetically operated, simple structure)
Cost	High	Low
Typical Application Scenarios	Substation outlet, main line segmentation point, important branch line start-up point	High-voltage side of distribution transformers, switching of reactive power compensation capacitor banks, general branch lines
Operating Method	Local manual, electric remote control, controlled by automation system (FTU)	Primarily locally manual operation (lever), electric operation is also optional
Compatibility with Fuses	Usually not required, has its own protection capabilities	Often used in combination with high-voltage fuses to form a "load switch-fuse combination appliance"
Automation Adaptability	High-performance, a key node device in distribution automation	Low voltage, mostly used as a disconnecting switch in automated circuits

 

In-depth analysis

 

1. Pole-Mounted Vacuum Circuit Breaker
You can think of it as a powerful "smart switch".

Working Principle: It not only has the ability to connect and disconnect circuits, but its core lies in the integrated current transformer (CT) and intelligent protection controller. The controller monitors the line current in real time. Once it detects a fault current exceeding the set value (such as a short circuit), it immediately sends a trip command to the circuit breaker's operating mechanism, automatically disconnecting the faulty line, preventing the accident from escalating, and ensuring normal power supply to non-faulty areas.

Core Advantages: Automation and selective protection. In distribution automation networks, multiple circuit breakers can work together to achieve automatic location and isolation of faulty sections and automatic restoration of power supply to non-faulty sections, greatly improving power supply reliability.

Application Examples:

On a long 10kV main line, one circuit breaker is installed at intervals, dividing the line into several sections. When a fault occurs in a section, only the circuit breakers at both ends of that section trip, and other sections are unaffected.

Installed at the entrance of important users or important branch lines as a protective switch for dedicated lines.

 

2. Pole-Mounted Vacuum Load Switch

You can think of it as a "manual/semi-automatic switch," with relatively simple functionality.

Working Principle: It is designed for frequently switching normal load currents (e.g., energizing or de-energizing a transformer). It lacks the ability to detect fault currents and automatically trip.

Core Advantages: Economical, simple, and reliable. It is a very economical choice in situations where complex protection is not required.

"Golden Partner" with Fuses: The most common application of load switches is in combination with high-voltage current-limiting fuses, commonly found on the high-voltage side of pole-mounted transformers.

Division of Labor:

Load Switch: Responsible for normal switching operations (e.g., cutting off current during transformer maintenance).

Fuse: Responsible for protection. When a serious fault such as a short circuit occurs inside the transformer, the fuse will quickly melt, cutting off the fault current.

This combination satisfies both ease of operation and effective protection, and its cost is far lower than using circuit breakers.

Application Examples:

Distribution Transformer Protection: The most common application is the combined protection of pole-mounted transformers using a load switch-fuse combination.

Line Segmentation: Used on non-automated lines to isolate line sections for easier maintenance.

Capacitor Bank Switching: Used for the connection and disconnection of reactive power compensation capacitors.

 

How to Choose?

 

The choice of equipment depends primarily on your specific needs in the power grid and your economic considerations:

Is automation and selective protection required?

Yes -> Choose a vacuum circuit breaker. It is the foundation for achieving distribution automation.

No -> Consider load switches or load switch-fuse combinations.

What is being protected?

Important main lines and branch lines -> Vacuum circuit breakers are preferred.

Single distribution transformers (such as pole transformers in residential areas or factories) -> Economical and reliable vacuum load switch-fuse combinations are preferred.

What is your budget?

Sufficient budget, pursuing high power supply reliability and automation levels -> Choose a vacuum circuit breaker.

Limited budget, and relatively simple protection requirements -> Choose a vacuum load switch.

 

Summary

In simple terms, circuit breakers are "active defenses," automatically identifying and eliminating threats (faults); while load switches are "manual gates," opening and closing only on command, requiring the use of fuses as "one-time safeguards" to deal with fatal threats.

In modern power distribution network construction, both have their place and complement each other. Vacuum circuit breakers are more commonly used in the backbone network to build intelligent and flexible distribution networks; while vacuum load switches, due to their economic efficiency, play an irreplaceable role in user access points and branch lines.

 

Shaanxi Huadian's product line covers multiple voltage levels from 12kV to 40.5kV, suitable for various critical locations such as power plants, substations, industrial and mining enterprises, rail transportation, and data centers. Whatever your needs, please contact us.

Email:pannie@hdswitchgear.com.

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