10kV Pole-Mounted Switches: Types, Functions, and Differences

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