10kV Pole-Mounted Switches: Types, Functions, and Differences
Pole-mounted switches are essential components in 10kV overhead distribution lines, particularly in suburban and rural power networks. Installed on outdoor utility poles, these switches are used for switching, isolating, and protecting overhead feeders. Depending on their function, they can interrupt load current, isolate circuits for maintenance, or disconnect fault currents.
A typical pole-mounted switch system includes a switch body (with sensor) and a Feeder Terminal Unit (FTU) for automation control. These switches form an integral part of outdoor distribution automation systems.
1. Classification of Pole-Mounted Switches
Based on switching capability, pole-mounted switches are classified as follows:
a. Pole-Mounted Disconnect Switch (Isolator)
No arc-quenching capability
Cannot open/close under load
Used to isolate lines for maintenance
Provides visible disconnection point
b. Pole-Mounted Load Break Switch (LBS)
Capable of switching normal load current (≤630A)
Cannot break short-circuit fault current
Equipped with arc-quenching device (e.g. vacuum or SF₆)
c. Pole-Mounted Circuit Breaker
Handles both load current and fault current (breaking capacity ≥20kA)
Provides automatic fault interruption and protection
Often integrated with FTU for remote monitoring and control
d. Pole-Mounted Fuse Cutout
Breaks short-circuit current during fault
Used for line protection and sectionalizing
Arc-Extinguishing Methods
Vacuum Interruption – widely used for LBS and circuit breakers
SF₆ Interruption – excellent arc quenching and insulation
Oil Interruption – now obsolete
Insulation Types
Air Insulated
SF₆ Gas Insulated
Composite Insulation
Oil Insulated – phased out
Control Types
Pole-mounted switches can be equipped with different controllers:
| Type | Description |
|---|---|
| Sectionalizer | With built-in zero-sequence CT for ground fault detection |
| Voltage-Type LBS | Automatically opens/closes based on voltage levels on both sides |
| Centralized LBS | Basic load switch, no active fault-clearing capability |
SF₆ gas is commonly used in modern switchgear due to its high dielectric strength and arc-quenching capability. It is a non-toxic, non-flammable, and stable gas, 5 times denser than air, offering excellent insulation.
2. Pole-Mounted Disconnect Switch (Isolator)
A pole-mounted isolator is a non-load break switch with no arc-quenching device. Its primary function is to safely isolate a section of the line for inspection or maintenance, by providing a visible air gap.
Key Features:
Simple design, low cost, and high reliability
Cannot break load or fault current
Used as ownership boundary switch (between utility and customer)
Ideal for maintenance isolation, fault identification, cable testing, and reconfiguration
Disconnect switches are widely used due to their robust construction and clear disconnection visibility. They’re often installed:
At the boundary of overhead and underground lines
Near user-owned equipment or branch feeders
On both sides of load break switches to facilitate isolation and replacement
Operating Sequence (for Safety):
Power ON: Close the isolator first, then the breaker or LBS
Power OFF: Open the breaker or LBS first, then the isolator
Technical Specs:
Cannot interrupt rated or fault current
Can switch small capacitive/inductive currents:
No-load transformer: ≤2A excitation current
No-load cable/line: ≤5A capacitive current
Short-time withstand current: typically ≤40kA
Mechanical endurance: ~2000 operations
Comparison Table of Pole-Mounted Switch Types
| Type | Switching Capacity | Function | Withstand Fault Current | Cost |
|---|---|---|---|---|
| Disconnect Switch | No load or fault current | Line isolation and visible disconnection | ❌ | Low |
| Load Break Switch | Load current (≤630A) | Regular line switching | ❌ | Medium |
| Circuit Breaker | Load + fault current (≥20kA) | Protection + automation | ✅ | High |
| Fuse Cutout | Short-circuit protection | Fault isolation and line protection | ✅ (with replacement fuse) | Low |
Applications of Pole-Mounted Switchgear
Rural & suburban 10kV overhead distribution networks
Ring main systems and feeder segmentation
Transformer station input/output
Smart grid automation and feeder fault detection
Distribution network reconfiguration & load transfer
Why Choose Our Pole-Mounted Switches?
Certified and tested for rugged outdoor use
Available in vacuum or SF₆ types
Support smart grid automation integration
Long mechanical life and low maintenance
Competitive pricing for global distribution
Contact Us
Looking for 10kV outdoor switchgear or pole-mounted switching devices? Our experienced engineers will help you choose the right disconnect switch, load break switch, or circuit breaker for your distribution system.
🌐 Website: [qz-switchgear.com]
📧 Email: info@qz-switchgear.com
📞 WhatsApp: +86-18625541622
