FLN36 Sulfur Hexafluoride Switch

Junray Electrical FLN36 Sulfur Hexafluoride Load Break Switch is a dedicated switching device specifically designed for 10kV ring main units (RMUs), cable branch boxes, and urban distribution networks. Unlike circuit breakers which are designed to interrupt short-circuit currents, this load break switch is optimized for making and breaking normal load currents in ring network applications, delivering reliable SF6 arc-quenching performance at a significantly lower cost. Featuring an integrated three-position design (Close, Open, Ground), a maintenance-free fully sealed SF6 gas compartment, comprehensive mechanical “Five-Prevention” interlocking, and a spring operating mechanism with a mechanical life of over 3,000 operations.

Product Advantages

SF6 Arc Quenching: Reliable Switching—Utilizing SF6 arc-quenching technology, this device boasts exceptional arc-extinguishing capabilities, enabling the reliable interruption and closing of load currents. Its arc-quenching performance significantly surpasses that of standard oil-immersed switches, making it perfectly suited for the switching operations required in ring network systems.

Load Current Switching: Optimized for Ring Networks—Specifically designed for the switching of load currents, this device is ideally tailored for ring network operations. It eliminates the need for the high-breaking capacity typically associated with circuit breakers; for typical ring network scenarios, its capabilities are entirely sufficient, resulting in substantial cost reductions.

High Reliability: Low Failure Rate—Ensuring highly stable operation, this device features an exceptionally low failure rate—approximately 30% lower than that of standard load switches. FLN36 Sulfur Hexafluoride Switch is perfectly adapted for ring network environments, offering peace of mind and eliminating concerns regarding equipment failure.

Product Parameter

Precision Engineering Details

1. Spring Operating Mechanism: Features a reliable spring operating mechanism that ensures dependable opening and closing operations, rapid switching speeds, and a low failure rate.

2. Fully Sealed Structure: Adopts a fully sealed design utilizing SF6 gas insulation; this maintenance-free structure requires no routine upkeep.

3. "Five-Prevention" Interlocking: Equipped with a "Five-Prevention" interlocking system to prevent operational errors and ensure the safety of 10kV high-voltage switching operations.

4. Standardized Installation: FLN36 Sulfur Hexafluoride Switch is designed for standardized installation, allowing for convenient integration into Ring Main Units (RMUs) and cable branch boxes.

Product Application

Ring Main Unit: The switching device within a Ring Main Unit, capable of making and breaking load currents.

High-Voltage Distribution: 10kV high-voltage power distribution systems, capable of making and breaking loads.

Ring Network Engineering: Ring network infrastructure projects, capable of making and breaking loads.

Choose Junray Electrical

Manufactured in strict compliance with national standards for High and Low Voltage Components, every unit undergoes rigorous sealing, switching, and withstand voltage tests to ensure stable and safe operation. Junray Electrical offer functional customization options, allowing you to tailor an exclusive FLN36 Sulfur Hexafluoride Switch specifically to the requirements of your ring network—ensuring a perfect fit for your ring main units and branch boxes.

Retrofit Case Study

I. Project Overview

This project involves the upgrade and renovation of aging 10kV distribution network ring main units (RMUs) serving local residential areas and street-front shops. The existing legacy gas-generating and oil-filled load break switches had been in service for a long time and suffered from issues such as insulation aging, abnormal operating noises, poor arc-extinguishing capabilities, susceptibility to moisture-induced breakdown, and an inability to reliably switch under load. On-site issues included switch jamming, insulation degradation, partial discharge, and condensation-induced tracking within the cabinets. These problems compromised safety during maintenance outages, hindered effective fault isolation, caused frequent unplanned power interruptions, and resulted in low supply reliability and significant operational risks.

To enhance distribution network stability, eliminate insulation hazards associated with aging switches, and support ring network sectionalizing and interconnection functions, the units were replaced with FLN36-12 indoor SF6 three-position load break switches. Serving as the core control component of the 10kV RMUs, these switches enable safe load current switching, reliable grounding, and precise isolation, meeting the operational requirements of standard urban ring network configurations.

II. Issues Prior to Retrofit

Poor insulation performance and multiple hazards: The legacy oil-filled and gas-generating switches utilized outdated insulation media. Long-term operation led to moisture absorption, aging, and severe partial discharge, creating a high risk of phase-to-phase breakdown and internal short-circuit faults.

Weak load-switching capability: Insufficient arc-extinguishing capacity meant that switching load currents often caused arcing and contact erosion, failing to meet the demands of frequent ring network switching operations.

Lack of standardized three-position structure and unsafe maintenance: The units lacked integrated isolation and grounding functions; grounding during maintenance was unreliable, posing risks of live maintenance or accidental contact.

Inadequate mechanical interlocking and risk of misoperation: The absence of anti-misoperation features created serious safety risks, such as closing the switch while under load or incorrect operation of the grounding switch.

High maintenance workload and failure rate: Regular inspections of oil levels and gas-generating component aging were required; parts wore out quickly, resulting in high O&M costs and poor power supply stability. 

III. Equipment Configuration Plan

In accordance with 10kV urban distribution network ring-main power supply standards and State Grid specifications for distribution equipment, the ring main units (RMUs) are uniformly equipped with FLN36-12D SF6 three-position load break switches. These switches feature an integrated structure combining closing, opening, and grounding functions, along with a comprehensive mechanical interlocking system. Designed for XGN15-12 RMU enclosures, they meet the requirements for sectionalizing, interconnection, and terminal power supply applications.

Core Equipment Parameters

Equipment Model: FLN36-12D Indoor High-Voltage SF6 Load Break Switch

Rated Voltage: 12kV (suitable for 10kV distribution networks)

Rated Current: 630A (meets maximum load current requirements for ring networks)

Insulation Medium: High-purity sulfur hexafluoride (SF6) gas; offers high dielectric strength and excellent arc-extinguishing performance

Structural Design: Integrated three-position design (closing, opening/isolation, and grounding)

Operational Functions: Load switching, no-load isolation, and reliable grounding for maintenance

Interlocking Configuration: Comprehensive mechanical "five-prevention" interlocking system; prevents closing the grounding switch under load, opening the cabinet while energized, and accidental switching operations

Operational Characteristics: Fully sealed structure, slight positive pressure operation, maintenance-free, moisture-resistant, and condensation-resistant

IV. Construction and Application Highlights

SF6 Gas Insulation with Superior Dielectric Performance: Utilizes high-purity SF6 gas; insulation and arc-extinguishing capabilities far surpass those of older oil-filled or gas-generating switches, effectively eliminating risks associated with humidity, condensation, and creepage breakdown.

Integrated Three-Position Design Ensuring Maintenance Safety: Opening the switch automatically achieves isolation; grounding is reliable and visually verifiable. Grounding protection is fully effective during maintenance, eliminating risks from residual voltage or accidental live work.

Mechanical "Five-Prevention" Interlocking for Error-Free Operation: Built-in forced mechanical interlocking with rigorous logic prevents all critical operational errors at the physical level.

Frequent Load Switching and Ring Network Compatibility: Excellent arc-extinguishing performance supports routine load switching and ring network power transfer, meeting the flexible dispatching needs of urban distribution networks. Fully sealed, maintenance-free, and requiring minimal O&M: The cabinet features a sealed, slight-positive-pressure design with an extremely low gas leakage rate; it requires no frequent gas replenishment or periodic disassembly for maintenance, ensuring stable long-term operation.

V. Operational Results After Retrofitting

Complete elimination of insulation hazards: The strong SF6 insulating medium prevents issues such as partial discharge, tracking caused by condensation, and phase-to-phase breakdown, ensuring the equipment's insulation level remains stable and compliant over the long term.

Flexible and reliable ring network switching: Smooth on-load switching without arcing or contact erosion ensures safe and stable distribution network dispatching and load transfer operations.

Safe and standardized maintenance procedures: A three-position isolation and reliable grounding system ensures maintenance conditions fully comply with safety regulations, eliminating the risks associated with live-line work.

Zero-maintenance equipment with extremely low failure rates: No routine maintenance or gas replenishment is required after commissioning; there is no degradation due to aging, and the equipment maintains a 100% operational integrity rate.

Significantly improved power supply reliability: Eliminates outage risks caused by equipment defects; enables rapid fault isolation and efficient load transfer, significantly reducing customer outage duration and ensuring successful acceptance under State Grid distribution network standardization criteria.

VI. Case Summary

The FLN36-12 SF6 load break switch is a core, standard component for 10kV ring main units (RMUs), box-type substations, urban distribution networks, and residential power distribution systems. It is primarily used for frequent load switching, line sectionalizing and interconnection, fault isolation, and maintenance grounding. Key advantages include superior SF6 insulation, an integrated three-position design, "five-prevention" interlocking, a maintenance-free nature, and on-load switching capability. Unlike circuit breakers, load break switches handle normal load switching and isolation rather than interrupting short-circuit faults, making them safe, stable, and cost-effective core switching devices within ring network power distribution systems.