DH1(VS1)-24 Handcart‑type Indoor Vacuum Circuit Breaker

General Description

The FL(R)N36(12‑40.5kV) SF6 high‑voltage load switch is a switchgear with rated voltage of 12‑40.5 kV. It adopts SF6 gas as the arc‑quenching and insulating medium. The switch has three working positions: closing, opening and earthing. It features compact size, easy installation and operation, and strong environmental adaptability.

This series of load switches includes two versions: FL(R)N36(12‑40.5kV) with Type‑K single‑spring operating mechanism, and FL(R)N36(12‑40.5kV) with Type‑A dual‑spring operating mechanism.

The FL(R)N36(12‑40.5kV) can be assembled into load‑switch‑fuse combination units with control and protection functions. It is used for control and protection of electrical equipment in power supply and substations. It is especially suitable for ring main units, cable distribution boxes and distribution switchgear stations.

Compliant with standards: IEC60265, IEC62271, GB3804, GB16926, etc.

Service Environmental Conditions

• Ambient temperature: Max. +40 °C, Min. ‑40 °C
• Humidity: Daily average relative humidity ≤ 95%; Monthly average relative humidity ≤ 90%
• Altitude: ≤ 2000 m
• Seismic resistance: 8‑degree seismic intensity
• The surrounding air shall be free from obvious contamination of corrosive or flammable gases, water vapor, and free from frequent violent vibration.
• Annual gas leakage rate: ≤ 0.1%

Special Conditions

When the load switch is applied at altitudes above 2000 m, special notification shall be given so that the design can be adjusted during manufacturing. Our load switches have proven safe operation at altitudes up to around 3000 m.

Structural Principle

Both the main circuit and earthing circuit of FLN36‑12D load switch are enclosed inside an epoxy‑resin insulating housing cast by APG process. It features excellent insulation and anti‑pollution performance.

The insulating housing is assembled by upper and lower insulating components and filled with SF6 gas at relative pressure of 0.4 bar. The lower insulator is equipped with explosion‑proof features. In case of fault, over‑pressurized SF6 gas is directed towards cabinet rear channel to guarantee personal safety.

Arc‑Extinguishing Principle

SF6 gas offers excellent arc‑extinguishing performance. When breaking current, an electric arc is generated upon contact separation. Driven by permanent‑magnet magnetic field, the arc rotates around contacts for rapid de‑ionization and cooling, and extinguishes at current zero‑crossing. After arc extinction, double break contacts provide isolating‑gap insulation level. This permanent‑magnet rotating‑arc principle delivers powerful arc‑quenching capacity, minimizes contact ablation and extends electrical service life.

Structural Features

Load switches and combination units consist of identical insulating housing main body, spring operating mechanism, fuse contact base and fuse striker‑trip system. The touch‑safe cable‑front‑type load switch comprises dedicated insulating housing switch body and universal spring operating mechanism. Upper and lower housings are epoxy‑resin cast to form gas‑filled cavity. The common moving contact rotates to complete three positions: Close‑Open‑Earthing. Motor‑driven close/open modules can be fitted onto manual spring‑charged operating mechanism for remote‑control operation as an option.

SF6 pressure gauge and position indicator are fitted on cabinet front face. The gauge monitors SF6 pressure variation. Position indicator couples directly with moving‑contact drive shaft to reliably show contact working status. A safety rupture disc is fitted at housing rear for pressure relief. When internal fault causes excessive pressure inside arc‑quenching chamber, the rupture disc bursts and releases gas toward rear side, avoiding forward gas jet and protecting personnel.

Reliable mechanical interlocks are provided between load switch & earthing switch, and between earthing switch & front door (interlock for cabinet application).