24kV Fixed Type SF6 Gas Circuit Breaker – 630A Medium Voltage VCB with Insulated Cylinder
The LYHM4 series is a high-performance indoor medium-voltage circuit breaker that utilizes sulfur hexafluoride (SF6) gas as both the arc-extinguishing and insulating medium. Designed for 24kV power distribution networks, it offers a rated current of 630A and ensures smooth switching characteristics without current chopping. Its excellent dielectric strength and thermal stability prevent operating overvoltages, providing a long electrical lifespan and reliable protection for high-voltage power distribution systems.
Product Overview
The LYHM4 Series Indoor High Voltage SF6 Gas Circuit Breaker is a high-performance medium-voltage solution designed for power distribution systems ranging from 12kV to 40.5kV. Utilizing sulfur hexafluoride (SF6) gas as the arc-extinguishing and insulating medium, this circuit breaker ensures smooth switching characteristics without current chopping. Its compact and lightweight structure, combined with advanced REH spring operating mechanisms, provides exceptional durability and reliable protection for modern electrical grids.
Key Features
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Superior Arc Extinction: SF6 gas provides excellent dielectric strength and thermal stability, preventing operating overvoltages during current interruption.
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Maintenance-Free Poles: The arc-extinguishing chamber is a sealed system requiring no maintenance throughout its service life, meeting IEC 62271-100 standards.
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Smooth Operation: Features an REH type spring operating mechanism for consistent closing and opening performance.
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Flexible Installation: Designed as a truck-mounted unit that can be easily pushed in or out along switchgear rails, even with the cabinet door closed.
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Integrated Intelligence: Compatible with the RCW series automatic recloser for integrated control, protection, measurement, and online monitoring.
Technical Specifications
Main Technical Parameters
| Item | Unit | LYHM-4 | LYHM-17 | LYHM-24 | LYHM-36 | LYHM-40 |
| Rated Voltage (Ur) | kV | 12 | 17.5 | 24 | 36 | 40.5 |
| Rated Insulation Voltage (Us) | kV | 12 | 17.5 | 24 | 36 | 40.5 |
| Power Frequency Withstand (Ud) | kV | 28 | 38 | 50 | 70 | 95 |
| Impulse Withstand Voltage (Up) | kV | 75 | 95 | 125 | 170 | 185 |
| Rated Operating Current (Ir) | A | — | — | 630 – 3600 | — | — |
| Rated Breaking Capacity (Isc) | kA | — | — | 12.5 – 50 | — | — |
| Mechanical Life | Times | — | — | 10000 | — | — |
Operating & Mechanical Parameters
| Item | Unit | Data |
| Rated Operating Sequence | – | 0-0.3s-CO-5s-CO |
| Breaking Time | ms | 45 |
| Arcing Time | ms | 10 ~ 15 |
| Closing Time | ms | 80 |
| SF6 Gas Absolute Pressure (24kV) | kPa | 380 |
| Weight (24kV) | kg | 119 |
Ambient Application Conditions
To maintain high performance and safety, the LYHM4 series should be operated under the following conditions:
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Ambient Air Temperature: -40°C to +40°C (Daily average ≤ 35°C).
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Relative Humidity: Daily average ≤ 95%; Monthly average ≤ 90%.
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Altitude: Not exceeding 1000m.
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