What Is A Ring Main Unit (RMU)?

What is a Ring Main Unit (RMU)?

Definition of a Ring Main Unit

A Ring Main Unit (RMU) is a set of power transmission and distribution equipment (high-voltage switchgear) housed in a metal or non-metal insulated cabinet or designed as an assembled modular ring power supply unit. Its core components include load break switches and fuses. RMUs are characterized by their simple structure, compact size, low cost, and the ability to improve supply parameters, performance, and safety.

Advantages of a Ring Main Unit

1. High Reliability

• The RMU adopts a fully enclosed design, effectively preventing environmental influences, minimizing fault rates, and significantly improving power supply reliability.

2. Strong Safety

• Equipped with comprehensive protection devices, such as overload and short-circuit protection, ensuring the safety of both equipment and personnel.

3. Easy Maintenance

• Modular design simplifies installation and maintenance, reducing operational costs.

4. High Adaptability

• Suitable for various environmental conditions to meet power distribution needs in diverse scenarios.

Classification of Ring Main Units

1. By Structure

• Fixed RMU: Suitable for long-term stable operation.

• Movable RMU: Ideal for scenarios requiring flexible layout.

2. By Insulation Medium

• Air-insulated RMU: Uses air as the insulation medium, offering lower costs.

• Gas-insulated RMU: Uses SF6 gas (Sulfur Hexafluoride) for superior insulation performance.

3. By Function

• Load Break Switch RMU: Used for switching load currents.

• Circuit Breaker RMU: Provides protection and control for power lines.

Key Application Areas

1. Urban Distribution Networks

• Used for branching and access points in urban grids, ensuring stable and efficient city power supply.

• Example: In a certain city, RMU coverage reached 95%, effectively improving supply reliability.

2. Industrial Parks

• Provides reliable power supply to industrial users, meeting high-load production demands.

• Example: In a large industrial park, RMUs process millions of kilowatt-hours of electricity daily.

3. Commercial Centers

• Ensures safe and stable power supply for large commercial complexes, supporting round-the-clock operations.