Structural Composition

The main components of multi-voltage grade ring main unit switchgear are listed as follows:

1. Metal Enclosure FrameFabricated from aluminum-zinc coated steel sheets by CNC cutting and laser bending, adopting fully bolted assembly without welding seams. The totally enclosed cabinet reaches IP2X protection grade, equipped with independent pressure relief channels for busbar and cable compartments.

2. Sealed Insulation TankStainless steel fully sealed tank filled with SF6 insulating gas, encapsulating all live components to realize maintenance-free operation, applicable for 11kV, 33kV and 40.5kV voltage grades.

3. Core Switching ComponentsEquipped with SF6 load break switch, earthing switch, vacuum circuit breaker, current transformers and voltage transformers, matched with corresponding specifications for different voltage levels.

4. Mechanical Interlock SystemStandard five-prevention interlock device installed between switching elements and cabinet door to block misoperation during inspection and maintenance.

5. Busbar SystemCopper or aluminum insulated busbars with standardized phase color coding, supporting flexible connection of multiple cabinet units for ring network layout.

6. Auxiliary Monitoring AccessoriesHigh-voltage live display device, gas pressure monitor, temperature sensor, breather, explosion-proof relief device and secondary control instrument cabinet.

Operating Principle

11kV/33kV/40.5kV ring main unit switchgear adopts SF6 gas insulation technology and works based on the principle of ring closed-loop power distribution.Multiple RMU cabinets are connected via busbars to form a closed ring power supply network. Under normal operation, power is transmitted bidirectionally along the ring loop. When a line fault occurs, the load switch or circuit breaker rapidly isolates the faulty segment, and power supply is automatically switched through the alternative loop to guarantee uninterrupted power for terminal loads. The sealed SF6 tank provides excellent insulation and arc-extinguishing performance to ensure stable operation under 11kV, 33kV and 40.5kV medium and high voltage conditions.

Advantages

1. Multi-voltage universal designCompatible with 11kV, 33kV and 40.5kV distribution systems, one platform meets various grid voltage demands.

2. Compact & space-saving layoutModular integrated structure greatly reduces floor area, suitable for underground pipe galleries and compact prefabricated substations.

3. Maintenance-free sealed structureFully sealed stainless steel gas tank avoids SF6 leakage, eliminating regular gas inspection and replacement work.

4. Complete safety protectionDual protection of mechanical interlock and pressure relief structure effectively prevents arc flash hazards and operator misoperation.

5. Wide environmental adaptabilityAnti-corrosion aluminum-zinc cabinet adapts to indoor and outdoor installation, stable performance under high humidity and severe weather conditions.

6. Intelligent expandabilityReserved installation space for FTU/DTU distribution automation modules to realize remote monitoring and automatic fault isolation.

Application Areas

1. Urban ring distribution power gridMunicipal power supply network, urban grid reconstruction, underground cable loop power supply projects.

2. New energy power stationsWind farms, photovoltaic power plants, energy storage station medium-high voltage ring network power distribution.

3. Industrial & mining heavy load projectsLarge factories, mining areas, chemical parks, metallurgical enterprises high-voltage power receiving and distribution.

4. Public infrastructureSubway stations, hospitals, data centers, commercial complexes and large residential communities.

5. Prefabricated compact substationsSupporting high-voltage incoming and ring network units for integrated box-type substations.