11kV / 12kV / 24kV / 36kV Outdoor Ring Main Unit (RMU)

1. What are the primary applications for Outdoor RMUs?

Our outdoor RMUs are specifically designed for secondary distribution networks, providing a "Ring" or "Terminal" power supply. They are ideal for urban street distribution, industrial parks, wind farm tower-base installations, and solar PV stations, where they step down or distribute 11kV–36kV power in open-air environments.

2. What is the standard Ingress Protection (IP) rating for your outdoor units?

Safety and durability are our priorities. Our outdoor RMU enclosures are typically rated at IP43 or IP54. While the external cabinet protects against rain and dust, the internal primary high-voltage components are hermetically sealed, providing an equivalent protection of IP67.

3. How do you ensure the RMU withstands harsh weather and corrosion?

Every outdoor cabinet is constructed from high-quality Alu-Zinc coated steel or Stainless Steel (304/316L). We apply a multi-layer electrostatic epoxy powder coating that is UV-resistant and salt-spray tested, ensuring a service life of over 30 years without rusting in coastal or humid climates.

4. What types of functional modules (C, F, V) can be configured?

Our RMUs feature a flexible modular design:

• C-Unit: Load Break Switch for incoming/outgoing ring cables.

• F-Unit: Switch-Fuse combination for transformer protection.

• V-Unit: Vacuum Circuit Breaker for high-capacity protection and frequent switching.

Units can be provided as a "Common Tank" (Compact) or "Extensible" (Modular) type.

5. Are your RMUs Gas-Insulated (GIS) or Solid-Insulated (SIS)?

We offer both technologies. Our GIS (SF6 Gas) models are ultra-compact and widely used for standard utility grids. Our SIS (Solid Insulated) models are 100% SF6-free and eco-friendly, making them the preferred choice for "Green" projects and high-altitude regions.

6. How does the RMU handle internal arc safety for operators?

Our outdoor RMUs are designed with Internal Arc Classification (IAC). In the rare event of an internal fault, the enclosure is equipped with pressure relief flaps (usually at the bottom or rear) to safely vent gases away from the operator, complying with IEC 62271-200 standards.

7. Can these RMUs operate in extreme temperatures or high altitudes?

Yes. Our RMUs are tested for a wide temperature range from -35°C to +50°C. For high-altitude projects (e.g., $>3000$m), we utilize enhanced insulation designs and specialized pressure monitoring to ensure consistent dielectric strength.

8. Does the Outdoor RMU support Smart Grid / Automation?

Absolutely. We can integrate an FTU (Feeder Terminal Unit) and motorized operating mechanisms. This enables "Three-Remote" functions (Remote Signaling, Measuring, and Control) via Modbus, IEC 60870-5-104, or IEC 61850 protocols for your SCADA system.

9. What protection devices are integrated for the transformer feeder?

For the transformer feeder (F-unit), we use High-Voltage Current-Limiting Fuses with a striker pin. In the event of a fault, the striker pin trips the load break switch to isolate all three phases simultaneously, preventing single-phasing of the transformer.

10. What testing and documentation do you provide for international shipping?

Every RMU from our Shanxi factory undergoes a full Factory Acceptance Test (FAT). For export, we provide a complete technical package in English:

• Single Line Diagrams (SLD) and GA Drawings.

• Type Test Reports (covering Short-circuit, Temperature Rise, and IP rating).

• Installation and Maintenance Manuals.