Ring Main Unit Sf6 Withdrawable Switchgear

What is the Ring Main Unit SF6 Withdrawable Switchgear?

The switchgear is a factory-assembled, metal-enclosed, SF6 insulated switchgear designed for medium voltage ring networks (up to 24kV/36kV). Unlike fixed-type RMUs, this withdrawable version features removable truck-mounted switching devices---typically a vacuum circuit breaker or SF6 load break switch that can be physically rolled out of the enclosure for maintenance, inspection, or replacement without de-energizing the entire busbar.

What can it do?

This Ring Main Unit SF6 Withdrawable Switchgear performs three critical functions in power distribution:

1. Ring network connection---Connects incoming feeders from two directions, enabling redundant power supply.

2. Transformer protection---Switches and protects distribution transformers up to 2500kVA using integrated fuses or a circuit breaker.

3. Isolation for maintenance---The withdrawable mechanism provides a visible breaking gap, ensuring absolute safety for personnel working downstream.

4. Fault interruption---Interrupts short-circuit currents up to 25kA.

5. Cable testing & grounding---Earth switch and cable test ports allow safe cable work.

Every SF6 RMU switchgear from Lugao Power complies with IEC 62271-200, offering both load make/break capability and fault current withstand in a compact footprint (width as low as 450mm per panel).

Product Parameter (Specification)

Note: Technical parameters may vary according to the selected configuration. Please contact Lugao Power for the final technical data sheet.

Product Feature And Application

Feature Q&A – Understanding the Withdrawable Advantage

Q1: What makes the withdrawable design better than a fixed RMU?

A: A fixed RMU requires full panel de-energization for switchgear maintenance. With a Ring Main Unit sf6 Withdrawable switchgear, you simply roll out the switching module to the “disconnected” or “test” position. The busbar remains live, and downstream circuits can be serviced safely. Downtime reduces from hours to minutes.

Q2: How do I know the withdrawable truck is in the correct position?

A: Lugao Power’s design includes three distinct mechanical positions---Connected, Test, and Disconnected---each with tactile feedback, visual indicators on the truck, and auxiliary contacts for remote SCADA monitoring. A safety shutter automatically covers fixed contacts when the truck is withdrawn.

Q3: Is SF6 gas maintenance-free in this withdrawable design?

A: Yes. The SF6 tank is sealed for life (≥30 years under normal conditions). The withdrawable mechanism is located in the low-voltage compartment or front truck area – not inside the gas tank. Therefore, withdrawing the switch does not disturb SF6 pressure or dielectric integrity. This is a key differentiable of the SF6 Withdrawable Ring Main Unit.

Q4: Does this RMU support remote control?

A: Yes. Withdrawable trucks can be fitted with motorized mechanisms and position feedback sensors, enabling full remote racking in/out – compatible with IEC 61850 GOOSE messaging.

Suitable Applications for SF6 insulated switchgear

Production Details

Each Ring Main Unit sf6 Withdrawable switchgear is produced in our ISO 9001 certified facility with dedicated assembly lines for fixed and withdrawable variants.

Key production steps:

1. Tank fabrication---3mm stainless steel, robotic laser welding, 100% helium leak test (leak rate <1×10⁻⁶ mbar·L/s).

2. SF6 processing---Vacuum filling with dew point ≤ -50°C, pressure calibrated at 20°C reference.

3. Withdrawable truck assembly---Precision guide rails, anti-friction rollers, self-aligning primary contacts (silver-plated copper, 12μm thickness).

4. Interlock tuning---Every unit undergoes 200 insertion/withdrawal cycles to verify mechanical interlocks.

5. High voltage test---Power frequency withstand: 42kV/1min (12kV units); partial discharge <5pC at 1.2Ur.

6. Temperature rise test---At 1.1× rated current, all points within standard limits.

7. Unique serial number---Engraved on both the enclosure and withdrawable truck for full traceability.

Quality Control Checkpoints

Packaging

Each Ring Main Unit sf6 Withdrawable switchgear panel is packed individually for export:

Markings on crate:

1. “SF6 Gas Filled – Do Not Drop”

2. “Withdrawable Truck Inside – Handle with Care”

3. Center of gravity, lifting points, fragile labels

The withdrawable truck is shipped inside the panel (in Disconnected position) to prevent damage. For orders with multiple trucks, optional separate packaging available.

After-Sales & Warranty

Warranty period: 

12 months from commissioning date or 18 months from shipment date (whichever occurs first).

What is covered:

1. All mechanical parts including withdrawable truck, interlocks, shutters

2. SF6 gas system (except gas refill due to customer leakage)

3. Primary and secondary contacts

4. Earth switch mechanism

What is not covered:

1. Damage during improper withdrawal/insertion

2. External wiring modifications

3. Acts of nature (flood, lightning)

4. Consumables (fuses, indicator lamps)

Service commitments:

1. Technical inquiry response: within 2 hours (working days)

2. Spare parts dispatch: within 24 hours

3. Remote troubleshooting: free video call support

Manufacturing & Quality Control

Lugao Power Co., Ltd. specializes in the R&D and manufacturing of high, medium, and low-voltage power transmission and distribution equipment, including transformers, switchgear, circuit breakers, disconnectors, and related electrical products.

With in-house production, engineering, and testing capabilities, Lugao Power provides customized OEM/ODM solutions and one-stop power distribution solutions for utilities, industrial facilities, renewable energy projects, and infrastructure applications worldwide.