Product Details

Product Classification by Load Switch Installation

Ring main units are divided into side-mounted and front-mounted types based on the mounting form of load switches.

1. Structure of Side-Mounted Ring Main Unit

The side-mounted RMU is composed of electrical components, cabinet enclosure and mechanical interlock system.

a. Electrical Components

Core electrical components are fixed firmly inside the cabinet, including:

• FN12-12 load switch with side-mounted operating mechanism

• VEI ISARC series load switch

• LKE LBS / VLBS series load switch

• Current transformers (CT)

• Voltage transformers (VT)

• High-voltage live display indicators

b. Cabinet Enclosure

The cabinet adopts a fully assembled modular structure, assembled by frame, top cover, front door and side shielding plates to form a totally enclosed metal housing. All frame, top cover, front door and side plates are manufactured by bending steel sheets.

c. Interlock Mechanism

Mechanical interlocks are equipped between load switch, earthing switch and cabinet front door to enforce mandatory operation logic:

1. If the load switch is closed, the earthing switch cannot be closed, and the front door cannot be unlocked or opened;

2. If the load switch is open, the earthing switch can be closed. Once the earthing switch is closed, the front door can be opened;

3. If the earthing switch is closed, the load switch cannot be closed, while the front door remains accessible to open;

4. If the earthing switch is open, the load switch can be switched on or off freely, but the front door is locked and cannot be opened;

5. For cable incoming cabinets: if the incoming cable is live (whether the load switch is closed or open), an electromagnetic lock will lock the front door. The door can only be manually unlocked with a special emergency key under emergency conditions.

2. Structure of Front-Mounted Ring Main Unit

The front-mounted RMU also consists of electrical components, cabinet enclosure and interlock mechanism.

a. Electrical Components

Main internal components include:

• FN12-12 load switch without side-mounted operating mechanism

• VEI ISARC type load switch

• LK LBS / VLS series load switch

• Current transformers, voltage transformers and high-voltage live indicators

b. Cabinet Enclosure

Modular fully assembled cabinet structure, consisting of frame, top plate, front doors, side shielding plates and integrated front operating mechanism.

c. Interlock Mechanism

The front-mounted RMU is equipped with a complete mechanical interlock system complying with standard safety interlock logic same as the side-mounted model.

3. Busbar Specifications

a. Available busbar materials: copper, aluminumb. Busbar color coding standards