An Indoor Load Break Switch (LBS) is a medium-voltage switching device designed specifically to be housed inside metal-clad switchgear cabinets (such as RMUs or secondary distribution panels). Operating in a controlled indoor environment, it relies on atmospheric air or vacuum to insulate the phases.
Unlike SF6-insulated models, standard indoor air-insulated LBS units typically use a puffer cylinder (compressed air) mechanism or a vacuum interrupter to rapidly stretch and cool the electrical arc generated when breaking active load currents, offering a highly cost-effective and environmentally friendly switching solution.
Features a built-in piston and cylinder. During the opening operation, the mechanism compresses air and blows it directly across the arc, stretching and cooling it until it safely extinguishes at the current zero-crossing.
Air-insulated indoor LBS units provide a clear, physical separation distance between contacts when open. This visible break offers absolute peace of mind to maintenance operators verifying the circuit is de-energized.
Integrated strictly with the switchgear door and earthing switch. The cabinet door cannot be opened unless the LBS is open and the earthing switch is fully engaged, adhering to strict "Five Preventions" rules.
The core breaking unit. It effectively extinguishes arcs in a vacuum, providing exceptional short-circuit breaking capacity while preventing contact oxidation.
Available with fuse bases and striker pin tripping linkages, allowing you to instantly convert the LBS into a full transformer protection unit.
Standard spring-charge manual operation can be quickly retrofitted with a 24V/110V/220V motor drive for remote SCADA control.
| Parameter | Unit | 12kV Indoor Series | 24kV Indoor Series |
|---|---|---|---|
| Rated Voltage | kV | 12 | 24 |
| Rated Current | A | 630 / 1250 | 630 |
| Rated Active Load Breaking Current | A | 630 | 630 |
| Short-Time Withstand Current (3s) | kA | 20 / 25 | 20 |
| Rated Short-Circuit Making Current | kA | 50 / 63 | 50 |
| Mechanical Endurance (Main Circuit) | Ops | 2000 (M1) / 5000 (M2) | 2000 |
| Insulating Medium | - | Atmospheric Air / Vacuum | |
Indoor LBS modules are strictly designed for use inside protective metal-clad switchgear cabinets (IP4X or higher). While the cabinet itself can be installed in an outdoor kiosk or substation housing, the switch mechanism must remain protected from direct rain, heavy condensation, and severe pollution.
Air-insulated (Puffer type) LBS provides an excellent, highly visible isolation gap and is extremely cost-effective for standard distribution. Vacuum-insulated LBS utilizes a vacuum interrupter to extinguish the arc, which significantly reduces contact wear, extends mechanical life, and is preferred for circuits requiring frequent switching operations.
Yes, we fully support switchgear manufacturers (Panel Builders). Upon request, we provide 2D dimensional drawings and 3D step models to help you seamlessly integrate our LBS into your custom cabinet layouts.
Submit your requirements on a business day, and our engineers will provide an initial OEM proposal within 24 hours.
We supply complete medium & high voltage solutions, including:
• Air Insulation Series
• Gas Insulation Series
• Switching Devices
• Instrument Transformers
