Huanghua Group Co., Ltd. 
Home Products Switchgear Medium Voltage HRM6-12/24 SF6 Gas-Insulated Metal-Enclosed Switchgear (Fixed-Type RMU)
HRM6-12/24 SF6 Gas-Insulated Metal-Enclosed Switchgear (Fixed-Type RMU)
The HRM6-12/24 series SF6 gas-insulated metal-enclosed switchgear (fixed-type RMU) is intended for 12 kV and 24 kV systems with SF6 load break switches rated up to 630 A / 1250 A / 2500 A at AC 50/60 Hz. All high-voltage live parts and switching elements are sealed inside a low-pressure SF6 gas tank, giving a compact structure that achieves miniaturisation, light weight and full insulation, in compliance with IEC 62271-200.
Send Inquiry Product Positioning
HRM6-12/24 is widely used in small secondary distribution substations, industrial and mining enterprises, airports, railways, commercial centres, high-rise buildings, highways and metro tunnels. Its modular design allows different modules to form a wide variety of main wiring schemes that can be changed to suit user requirements, creating a complete circuit switching system. Silicone-rubber connectors enable the splicing of HV components and unlimited extension of the cabinet, while all incoming and outgoing lines use screened cables. Circuit-breaker cabinets, HV monitoring devices, integrated digital relays and HV metering tanks can be configured, and remote control/monitoring units and over-current protection relays can be fitted — fully meeting distribution network automation upgrade requirements.
Type Designation
Key Highlights
| Highlights | Customer Value |
| Fully sealed and insulated: all HV parts and switching elements sealed in a low-pressure SF6 tank, IP67 gas compartment | Immune to humidity, salt spray, condensation and pollution — maintenance-free |
| SF6 pressure 1.4 bar (absolute at 20 °C), leakage rate ≤0.25% | Long sealing life, minimal gas refill and testing cost |
| Verified for harsh environments: passed 0.3 bar underwater immersion test for 24 hours | Flood-proof — safe in tunnels, basements, coastal and flood-prone sites |
| Internal arc performance: verified by arcing test at 20 kA / 1 s; no arcing at 16 kA / 1 s | Personnel and adjacent equipment protected under fault conditions |
| Modular and freely extensible: C / F / V / CB modules combined at will and spliced with silicone-rubber connectors | Main wiring changed on demand; expansion without replacing the whole unit |
| Compact and miniaturised: 371 mm wide for a single circuit, only +325 mm per additional circuit | Far smaller than AIS — ideal for compact substations and prefab housings |
| Automation ready: integrated digital relay, HV monitoring device, optional remote monitoring and over-current protection | Telemetry, remote signalling and control — ready for distribution automation |
| 24 kV platform TÜV SÜD certified, compliant with the IEC 62271-200 series | Recognised by international buyers; smoother compliance review on export projects |
Product Features
| Features | Description |
| Hermetically Sealed Tank, Fully Insulated | All HV live parts and switching elements are sealed inside a low-pressure SF6 gas tank, achieving miniaturisation, light weight and full insulation. Live parts are never exposed to the external environment, so operation is unaffected by climate. |
| SF6 Insulation & Pressure Management | SF6 gas pressure is 1.4 bar (absolute at 20 °C) with an annual leakage rate ≤0.25%. An optional temperature-compensated density relay provides alarm and lockout contacts for visualised and remote monitoring of gas condition. |
| Immersion & Flood Resistance | Passed the 0.3 bar underwater immersion test for 24 hours, demonstrating reliable compartment sealing. Suitable for metro tunnels, basements, coastal and flood-prone distribution rooms with outstanding flood resistance. |
| Internal Arc Performance Verification | Verified by internal arc tests: arcing occurs at 20 kA / 1 s while no arcing occurs at 16 kA / 1 s. A non-rupturable pressure-relief diaphragm on the tank roof discharges to the top of the cabinet, protecting operating and maintenance personnel. |
| Harsh Environment Capability | Operates reliably under harsh conditions including condensation, frost, salt fog, pollution, corrosion, UV radiation, small animals and chemicals — suitable for outdoor, coastal, tunnel and industrially polluted areas. |
| Modular Design & Free Combination | The modular design allows C (load break switch), F (switch-fuse), V (vacuum switch/circuit breaker) and CB (circuit breaker) modules to form a wide variety of main wiring schemes that can be modified to user requirements, creating a complete circuit switching system. |
| Silicone-Rubber Connector & Free Extension | Silicone-rubber connectors enable splicing of HV components and unlimited extension of the cabinet, with reliable insulating interfaces and simple on-site bay joining — later additions require no modification to existing units. |
| Fully Screened Cable Terminations | All incoming and outgoing lines use screened cables. Combined with screened cable terminations and the cabinet earthing system, this gives a uniform electric field distribution and effectively suppresses partial discharge and electromagnetic interference. |
| Integrated Digital Relay & HV Monitoring | Fitted with HV monitoring devices and an integrated digital relay for real-time condition monitoring; remote control and monitoring units plus over-current protection relays can be added, meeting distribution network automation upgrade requirements. |
| HV Metering Package | A high-voltage metering tank can be provided for medium-voltage energy metering and assessment, facilitating sub-metering and settlement in industrial parks, commercial complexes and distributed energy projects. |
| Maintenance-Free & Low Operating Cost | The sealed structure and long-life design deliver flood resistance, long service life, maintenance-free operation and low operating cost. No periodic cleaning or insulation maintenance is required, significantly reducing whole-life cost. |
| Compact Dimensions & Lightweight Structure | A single-circuit unit is only 371 mm wide, with each additional circuit adding just 325 mm. The compact, lightweight structure facilitates transport, lifting and retrofitting of existing distribution rooms. |
Technical Parameters
1.Basic Data
| Item | Data | Unit |
| Product Name | SF6 gas-insulated metal-enclosed switchgear (fixed-type RMU) | — |
| Model | HRM6-12 / HRM6-24 (HRM6-12/24 fixed type) | — |
| System voltage | 12/24 | kV |
| Rated frequency (fr) | 50 / 60 | Hz |
| Rated current (SF6 load break switch) | Up to 630 / 1250 / 2500 | A |
| Module types | C load break switch / F switch-fuse / V vacuum switch / CB circuit breaker | — |
| Functional units | Circuit-breaker cabinet, HV monitoring device, integrated digital relay, HV metering tank, remote control & monitoring unit, over-current protection relay | — |
| Cable arrangement | All incoming and outgoing lines use screened cables | — |
| Extension method | Silicone-rubber connectors for splicing HV components and unlimited cabinet extension | — |
| Application scope | Small secondary distribution substations, industrial and mining enterprises, airports, railways, commercial buildings, high-rise buildings, highways and metro tunnels | — |
2.Insulation Level & Breaking Capacity (by module)
| Item | Data | Unit |
| Rated voltage (all modules) | 12 / 24 | kV |
| Power-frequency withstand voltage (all modules) | 42 / 50 | kV |
| Lightning impulse withstand voltage (all modules) | 95 / 125 | kV |
| Rated current — C module (LBS) | 63 / 630 | A |
| Rated current — V module (vacuum switch) | 630 / 630 | A |
| Rated current — CB module (VCB) | 1250 / 630 | A |
| Rated current — F module (switch-fuse) | Depending on the fuse current rating | A |
| Closed-loop breaking current — C module | 63 / 630 | A |
| 5% of rated active load breaking current — C module | 31.5 / — | A |
| Cable-charging breaking current — C module | 135 / 135 | A |
| Ground fault tripping current — C module | 200 / 150 | A |
| Cable-charging breaking current under earth fault — C module | 115 / 87 | A |
| Short-circuit breaking current — V module | 20 / 16 | kA |
| Short-circuit breaking current — CB module | 25（20） 25 (20) |
kA |
| Short-circuit breaking current — F module | Limited by the high-voltage fuse | kA |
| Making capacity (ON-OFF) — C module | 63 / 52.5 | kA |
| Making capacity (ON-OFF) — V module | 50 / 40 | kA |
| Making capacity (ON-OFF) — CB module | 63（50） 63 (50) |
kA |
| Short-time withstand current 2 s — C module | 25 / — | kA |
| Short-time withstand current 3 s — C module | — / 21 | kA |
| Short-time withstand current 3 s — V module | 20 / 16 | kA |
| Short-time withstand current 3 s — CB module | 25（20） 25 (20) |
kA |
3.Mechanical Endurance
| Item | Data | Unit |
| Mechanical life — C module (LBS) | 5000 | ops |
| Mechanical life — F module (GIS switch-fuse) | 3000 | ops |
| Mechanical life — V module (vacuum switch) | 5000 | ops |
| Mechanical life — V module (isolating/earthing switch) | 2000 | ops |
| Mechanical life — CB module (VCB) | 10000 | ops |
| Mechanical life — CB module (isolating/earthing switch) | 2000 | ops |
4.SF6 Gas & Sealing
| Item | Data | Unit |
| SF6 gas pressure | 1.4 | bar |
| SF6 gas leakage rate | ≤0.25 | % |
| Immersion test | 0.3 bar underwater for 24 hours | — |
| Arc testing | Arcing at 20 kA / 1 s; no arcing at 16 kA / 1 s | — |
| Protection degree — gas compartment | IP67 | — |
| Pressure-relief device | Non-rupturable diaphragm on tank roof, vented to cabinet top | — |
| Gas density monitoring | SF6 density relay (optional), temperature-compensated, with alarm and lockout contacts | — |
| Sealing structure | Laser-welded longitudinal seams with elastomeric O-ring seals at manway/penetrations | — |
| Insulating medium options | SF6 (standard) / eco-gas (N₂ or dry-air blend, on request) | — |
5.Construction & Dimensions
| Item | Data | Unit |
| Construction type | Fixed type, modular, fully insulated and sealed | — |
| Width A — 1 circuit | 371 | mm |
| Width A — 2 circuits | 696 | mm |
| Width A — 3 circuits | 1021 | mm |
| Width A — 4 circuits | 1346 | mm |
| Width A — 5 circuits | 1671 | mm |
| Increment per additional circuit | 325 | mm |
| Cabinet enclosure | Galvanised steel, epoxy powder-coated (RAL 7035, custom RAL available) | — |
| Protection degree — cabinet exterior | IP3X (upgradeable to IP54) | — |
| Busbar & extension joint | SF6-insulated common busbar with plug-in joint (silver-plated finger contacts, bellows-guarded) | — |
| Cable entry | Bottom entry, screened cables with screened terminations | — |
| CT / PT | Cable-side protection CT built into the tank; PT module for metering | — |
| Earthing switch | Earthing switch per bay (De function), interlocked with the three-position LBS | — |
6. Service Conditions
| Item | Data | Unit |
| Ambient air temperature | -15 to +40 (-25 to +45 available as customised products) | ℃ |
| Altitude | ≤1000 | m |
| Relative humidity | Daily average ≤95; monthly average ≤90 | % |
| Water vapour pressure | Daily average ≤2.2; monthly average ≤1.8 | kPa |
| Earthquake intensity | ≤ magnitude 8 | — |
| Applicable places | Places without steam, explosion hazard, corrosive or flammable gas | — |
| Harsh environment capability | Suitable for condensation, frost, salt fog, pollution, corrosion, UV radiation, small animals and chemicals | — |
7.Standards & Certification
| Item (EN) | Data | Unit |
| Main standard | IEC 62271-200 — High-voltage switchgear and controlgear: AC metal-enclosed switchgear and controlgear for rated voltages above 1 kV and up to and including 52 kV | — |
| Circuit-breaker standard | IEC 62271-100 — Alternating-current circuit-breakers | — |
| Disconnector & earthing switch standard | IEC 62271-102 — Alternating current disconnectors and earthing switches | — |
| Load break switch standard | IEC 62271-103 — Switches for rated voltages above 1 kV up to and including 52 kV | — |
| Switch-fuse combination standard | IEC 62271-105 — Alternating current switch-fuse combinations | — |
| Common specifications | IEC 62271-1 — Common specifications for high-voltage switchgear and controlgear | — |
| National standards | GB/T 11022-1999, GB 3906-2006, GB 1985-2004, GB 16926, GB 3804-2004, GB 1984-2003, GB 3309-89 (China national standards) | — |
| IP code standard | IEC 60529 — Degrees of protection provided by enclosures (IP Code) | — |
| Certification status | 24 kV platform: TÜV SÜD certified (type test + factory surveillance); same ISO 9001 QA system with identical laser-weld and helium-leak workflow | — |
8.Module Combinations & Options
| Item | Description | Applicability |
| C module — Load break switch | Three-position (close–open–earth) SF6 load break switch, 5,000 operations mechanical life | ring in/out |
| F module — Switch-fuse combination (GIS) | Transformer protection, breaking capacity limited by the HV fuse, 3,000 operations | transformer feeder |
| V module — Vacuum switch + isolating/earthing switch | Rated 630 A, breaking 20/16 kA, mechanical life 5,000 / 2,000 operations | feeder & transformer protection |
| CB module — VCB + isolating/earthing switch | Rated 1250/630 A, breaking 25(20) kA, mechanical life 10,000 / 2,000 operations | incomer & large feeders |
| Earthing / disconnector function | Earthing switch provided per bay, interlocked with the three-position LBS | maintenance earthing |
| HV metering tank | Optional HV metering tank for medium-voltage energy metering and assessment | metering & settlement |
| Silicone-rubber connector (extensibility) | Enables splicing of HV components and unlimited cabinet extension without de-gassing adjacent units | extension |
| HV monitoring device | Monitors operating condition; optional SF6 density relay with alarm and lockout contacts | condition monitoring |
| Integrated digital relay | Integrated protection, measurement, control and communication | protection & automation |
| Over-current protection relay | Over-current protection can be added to suit different short-circuit levels and settings | over-current protection |
| Remote control & monitoring unit | Remote monitoring can be added, supporting telemetry, remote signalling, remote control and DA master integration | distribution automation |
| Internal arc class IAC A-FLR (on request) | With pressure-relief ducts per IEC 62271-200 Annex AA; catalogue: arcing at 20 kA / 1 s, none at 16 kA / 1 s | high personnel-safety sites |
| IP54 enclosure (on request) | Gasketed door with rain louvre and filter for coastal, dusty and outdoor sites | outdoor/dusty |
| Eco-gas option (on request) | N₂ / dry-air blend replacing SF6 (subject to confirmed supply capability) | low-emission markets |
