| Brand | ROCKWILL |
| Series | KYN,RAR,RMR |
The 40.5kV class is the top of medium voltage — the last step before high voltage transmission. ROCKWILL builds the complete set: air-insulated metalclad panels, G3 clean-gas and SF6 ring main units, outdoor RMUs and cable branch boxes, all type-tested to IEC 62271.
Overall view
40.5kV switchgear is metal-enclosed medium voltage equipment rated for systems up to 40.5kV, the highest MV class before 72.5kV high voltage. It sits at the interface between the distribution network and the substation: receiving power from the 110kV/220kV transformer, switching and protecting feeders, and feeding 33kV, 35kV and 36kV sub-networks.
Because it handles the largest currents and fault levels in the MV range, 40.5kV equipment is specified around three things: dielectric margin (95kV power-frequency and 185kV lightning impulse are typical), short-circuit capability (20–40kA for 3–4 seconds), and safety architecture — compartmentalisation, interlocks, and remote operation.
ROCKWILL covers all three insulation philosophies — air-insulated metalclad for indoor substations, sealed SF6 gas for compact footprints, and G3 clean gas for F-gas-free projects — so the same 40.5kV network can be engineered consistently from the incoming panel to the last outdoor branch box.
Portfolio
Four product families, one voltage class. Each product links to its dedicated page with full specifications and documentation.
KYN61-40.5(Z) withdrawable metalclad panel for utility substations and large industrial plants. Withdrawable VCB units can be inspected without de-energising the whole board.
RAR series air-insulated, metal-enclosed switchgear with withdrawable vacuum circuit breaker. Interchangeable cassettes for feeder, incoming and transformer duties.
G3 clean-gas RMU — the SF6-free route to 40.5kV, sealed for life with no gas top-up schedule.
IEC-standard sealed SF6 RMU — proven compact solution for 33kV to 40.5kV networks.
Compact G3 RMU for primary distribution and sub-transmission, one sealed tank from 12kV to 40.5kV.
RGIS welded stainless-steel, pressure-sealed outdoor RMU with IP65 protection and pressure-relief duct. Busbar ratings up to 3150A.
DFW outdoor high-voltage cable branch box / kiosk RMU, 3.3kV to 40.5kV, silicone-rubber-clad connectors and optional SF6 load break switch.
Outdoor 40.5kV disconnector for isolating feeders and transformer circuits during maintenance.
Selection guide
Same voltage, different physics. Choose by footprint, climate policy, ambient conditions and maintenance model — not by habit.
| Route | Air-insulated metalclad | SF6 gas-insulated | G3 clean gas | Outdoor kiosk / branch box |
|---|---|---|---|---|
| Dielectric | Air at atmospheric pressure | Sealed SF6 | Sealed G3 (fluoro-ketone) | Air + silicone-clad connectors |
| Footprint | Largest — needs indoor switch room | Smallest — compact tank | Compact, slightly larger than SF6 | Cabinet footprint, outdoor |
| GWP / F-gas | None | Very high (SF6) | Near-zero, no F-gas reporting | None unless SF6 LBS option |
| Maintenance | Periodic inspection, withdrawable cassettes | Sealed for life, pressure monitoring | Sealed for life, maintenance-free | Maintenance-free |
| Typical use | Utility & industrial indoor substations | Retrofit, tight urban rooms | F-gas-free tenders, green projects | Cable branch, remote outdoor nodes |
| ROCKWILL series | KYN61-40.5, RAR | RMR (SF6) | RMR / REC (G3) | DFW, RGIS |
| Application | Recommended family | Why |
|---|---|---|
| Indoor utility substation, 40.5kV incoming & feeders | Metalclad KYN61-40.5 / RAR AIS | High current to 3150A, withdrawable maintenance, full interlocking |
| Compact urban distribution room | SF6 or G3 RMU | Tank footprint fits restricted rooms; sealed for life |
| Project with F-gas / GWP cap | G3 RMU 33/35/40.5kV | Near-zero GWP with no SF6 reporting obligation |
| Outdoor cable branch / remote node | DFW kiosk RMU, RGIS | Weather-resistant enclosure, IP33 to IP65, no exposed live parts |
| Wind, solar and industrial plants | RGIS outdoor RMU, RAR AIS | High fault level 31.5–40kA and wide ambient range |
Compliance & quality
Designs are type-tested at recognised high-voltage laboratories, including the China Electric Power Research Institute and Xi'an High Voltage Apparatus Research Institute.
IEC 62271-1 (common clauses), IEC 62271-200 (metal-enclosed switchgear), IEC 62271-102 / -103 (disconnectors and RMUs), IEC 60529 for IP ratings.
Configuration drawings, routine test reports, IEC documentation for tenders and spare-part support across the service life of the board.
It is the top medium voltage class, used at the boundary between distribution and high voltage: receiving power from 110kV/220kV transformers, switching and protecting feeders, and supplying 33kV, 35kV and 36kV sub-networks.
35kV is the system voltage; 40.5kV is the equipment-rated insulation class specified for it. A 40.5kV board is the standard way to switch a 35kV network, with 95kV AC and 185kV impulse withstand.
Air-insulated metalclad is the choice when a switch room is available and currents reach 2500–3150A; gas-insulated RMUs win when space is tight. G3 adds a near-zero-GWP option without SF6 reporting.
Rated short-time withstand ranges from 20kA to 40kA for 3 or 4 seconds, with peak withstand of 50–100kA depending on the family and configuration.
Yes. Ring layouts, current ratings, protection relays, cable terminations, enclosure colour and nameplate can be customized, with IEC 62271 documentation issued under your brand for tenders.
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