Solid-Insulated Design — Epoxy-Encapsulated Live Parts
The primary conductive parts — main busbar and the moving parts of the high-voltage switching devices — are fully encapsulated inside an epoxy resin cast shell. There is no gas involved in the insulation function. Practically this means three things at once: there is no gas leakage pathway to monitor, the insulation performance is not tied to a gas pressure gauge, and the switchgear qualifies as a genuinely zero-GWP alternative to SF6-insulated designs. For utilities and industrial operators subject to the EU F-Gas Regulation (Regulation EU 2024/573), a solid-insulated RMU is an SF6-free replacement path — one of two mainstream SF6-alternative technologies in medium voltage, alongside gas-insulated dry-air designs.
IP67 Switching Body — Condensation and Short-Term Flood Resistance
The switching body itself is rated IP67. In practice this means the encapsulated switching mechanism can be exposed to condensation for extended periods without dielectric degradation, and can withstand short-term water immersion during an unexpected flood event without permanent damage to the insulation system. This is a real distinction versus air- or gas-insulated RMUs: in those designs, an outer IP4X cabinet is the only barrier between the outside environment and the live-parts compartment, so any water ingress into the cabinet compromises insulation performance immediately. Applications include below-grade substations in coastal cities, distribution stations in tropical humid climates and installations in flood-risk floodplains.
Altitude-Independent Performance for Plateau Installations
Gas-insulated switchgear derates with altitude, because atmospheric pressure drops and the dielectric strength of the gas insulation drops with it — typically the standard qualification runs to 2000m before a composite-insulation or oversized-clearance variant is required. Solid insulation does not have this problem: the epoxy resin encapsulation is a fixed-density solid, and its dielectric strength is independent of ambient pressure. That is why the platform is specifically flagged as suitable for high-altitude installations. On plateau grid projects in western China, the Andean highlands, the Himalayan foothills and other elevated regions, this saves the derating study, the enlarged cabinet footprint, and the specialised commissioning that gas-insulated alternatives require.
Low Partial Discharge (<10pC at 14.4kV) — Verified Insulation Quality
Partial discharge measured at 14.4 kV (1.2 times rated voltage) stays below 10 pC. Partial discharge is the first observable indicator of insulation degradation in a solid-insulated design — years before a full insulation failure — so a low pc reading on the factory acceptance test is a durable predictor of long service life. Below 10 pC is a strict internal quality gate; testing beyond the standard requirement filters out any epoxy castings with micro-voids or dielectric weaknesses before shipment.
Modular Unit Types — C / V / S / M / PT Any Combination
Five standard functional unit types are available: C-unit (load-break switch), V-unit (vacuum circuit breaker), S-unit (bus-section switch), M-unit (metering cabinet) and PT-unit (bus voltage transformer). Any combination can be assembled through the dedicated busbar connection pieces, so an RMU line-up matches the single-line diagram exactly rather than forcing the diagram to fit a fixed catalogue of pre-built units. This flexibility matches the diversity of Chinese distribution designs and is equally useful on export projects where the utility's connection standard differs from the manufacturer's default.
DIN 47636 Cable Bushings with Fully-Insulated Screened Connectors
Cable connections use DIN 47636-standard bushings, mated with fully-insulated and screened separable cable connectors — the elbow-connector interface familiar to European utilities and IEC-market EPCs. Every conductive surface at the cable interface is covered by an earthed screen, so the interface is safe to touch during connection work and there is no exposed live metal even when the panel is energised. This is an important detail on retrofit projects: existing cable stocks with standard elbow-connector terminations plug straight into the new RMU without adapter engineering.
AFLR 25kA / 1s Internal Arc Classification
Internal arc classification reaches AFLR 25kA / 1 second — with accessibility verified on Front (A), Lateral (L) and Rear (R) sides. This is a stricter rating than the AFLR 20kA / 0.5s common to compact gas-insulated RMU designs, and reflects the mechanical robustness of the epoxy-encapsulated construction under fault energy release. The solid-insulation geometry itself contains a large portion of the arc energy before pressure-relief mechanisms activate.
Applications: High-Altitude, Humid, Flood-Risk and Green Renovation
Four demand segments drive the case for a solid-insulated RMU. First, high-altitude installations where gas-insulated designs derate and become uneconomical — plateau grids, mining sites, mountain wind farms. Second, high-humidity and condensation-prone environments — coastal utilities, tropical cities, below-grade substations. Third, flood-risk zones where short-term water immersion is a credible scenario — river-basin cities, monsoon-region industrial sites. Fourth, utilities and grid operators pursuing SF6 phase-out under F-Gas Regulation, national green renovation programmes or corporate ESG commitments — solid-insulated equipment is one of the two mainstream SF6-free technologies (alongside dry-air/nitrogen-insulated designs), and typically the more compact choice at 12kV.
