SF6 Three-Position Load Switch

1. Product Overview

SF6 three-position load switch is an essential high-voltage primary switching device widely used in 10kV indoor ring main units, compact switchgear, metering cabinets, photovoltaic power stations and urban distribution network projects. It adopts sulfur hexafluoride (SF6) gas as arc extinguishing and insulating medium, integrating three working positions: closing, opening and earthing.

This switch can complete normal load current breaking, circuit isolation and reliable earthing protection in one unit. Fully sealed gas tank design avoids external dust and moisture interference, featuring stable insulation performance, long service life and compact layout. It fully meets IEC international standards, ideal for global industrial, commercial and new energy medium-voltage power distribution projects.

2. Main Features

• Integrated three-position design: Close / Open / Earth function in one device
• SF6 gas as arc-extinguishing & insulating medium, excellent arc quenching capacity
• Fully sealed metal tank, free maintenance for long-term operation
• Compact structure, small occupied space, easy to install inside RMU
• Visible earthing isolation gap for safe maintenance
• Manual spring operating mechanism, smooth and reliable operation
• Supports 50Hz / 60Hz dual frequency to fit global power grids
• Low partial discharge, stable performance under various climate conditions
• With interlock device to prevent misoperation, improve operation safety
• Suitable for frequent load switching operation

3. Technical Specifications

4. Structure Description

5. Working Principle

The switch relies on high-insulation, high arc-extinguishing performance SF6 gas to complete load breaking.

1. Closing position: Main contacts are connected, high-voltage circuit is conducted normally to transmit load current.
2. Opening position: Main contacts separate to form isolation fracture, cut off load circuit, no earthing connection.
3. Earthing position: Main contacts remain separated, earthing contact closes to short circuit the outgoing line to ground, eliminating residual voltage for safe maintenance.

Built-in mechanical interlock ensures the main switch and earthing switch cannot close at the same time to prevent short-circuit accident. When breaking load current, SF6 gas instantly cools and extinguishes electric arc to avoid contact ablation.

6. Application Scope

SF6 three-position load switch is matched with the following medium-voltage equipment:

10kV ring main unit (RMU)

Compact packaged substation

High voltage metering cabinet

Photovoltaic & energy storage medium voltage cabinet

Urban overhead cable distribution box

Industrial factory power distribution room

Commercial complex power supply system

Municipal power grid reconstruction projects

Wind power collection station switchgear

7. Installation Instructions

1. Check the gas tank before installation to confirm no air leakage, deformation or scratch on stainless steel surface. Verify rated parameters match project drawings.
2. Fix the switch firmly on the cabinet mounting beam with special fasteners to avoid vibration during operation.
3. Connect incoming and outgoing cable terminals tightly, guarantee sufficient insulation clearance between live parts and cabinet shell.
4. Assemble the external operating handle and adjust transmission shaft to ensure smooth switching among three positions.
5. Test mechanical interlock function strictly: confirm main switch and earthing switch cannot close simultaneously.
6. Check SF6 gas pressure value to meet factory standard before power transmission.
7. No need for internal maintenance during service life; only regular gas pressure inspection required.

8. Safety Warnings

1. All installation, commissioning and inspection work must be operated by certified professional electrical technicians.
2. Do not open the sealed gas tank arbitrarily; SF6 gas filling and maintenance need professional equipment.
3. Strictly follow interlock operation sequence: Open main switch first, then close earthing switch for maintenance.
4. Never touch cable terminals and live components before switching to earthing position.
5. Stop operation immediately if gas pressure drops sharply or abnormal discharge sound appears, cut off upstream power supply for inspection.
6. Avoid strong impact and extrusion on gas tank during transportation and installation to prevent air leakage.
7. Keep product nameplate and factory technical data sheet for later maintenance reference.

9. Ordering Information

Please provide below technical requirements when placing orders:

1. Rated short-time withstand current
2. Rated load current
3. Cabinet installation size limit
4. Operating mechanism type (standard manual)
5. Quantity
6. Applicable international standard (IEC as default for overseas market)

10. Packing & Export Note

Each SF6 three-position load switch is wrapped with shockproof foam, fixed in solid wooden export case. Wooden cases are reinforced with steel strips to resist collision, vibration and dampness during sea, land and air long-distance transportation. Neutral English labels without brand logo are attached on outer package, convenient for overseas customs clearance and storage.