High-Voltage Switchgear: How to Choose the Right RMU or Metal-Clad Unit

2026-08-14 17:46:45

Electrical complete equipment refers to factory-assembled power distribution systems that integrate switching, protection, metering and control devices into a single enclosure. Rather than assembling individual components on site, engineers receive a tested, ready-to-install solution that reduces construction time, improves safety and ensures consistent performance.

What Is Electrical Complete Equipment?

In power engineering, “complete equipment” (成套电气设备) covers a wide range of prefabricated assemblies designed to receive, transform, distribute and protect electrical energy. These assemblies are built according to national and international standards such as GB/T 11022, GB 3906, GB 7251.1, IEC 62271 and IEC 60439, and they are tested as complete units before shipment.

Main Categories in a Complete Equipment Portfolio

High-Voltage Switchgear

High-voltage (HV) switchgear is used in substations and ring networks from 3.6 kV up to 40.5 kV. Common types include:

• Gas-insulated ring main units (RMUs): compact, fully sealed cabinets using SF₆ or eco-friendly dry air as the insulating medium.

• Solid-insulated RMUs: use epoxy resin casting for all live parts, making them ideal for humid, polluted or high-altitude sites.

• Air-insulated RMUs: cost-effective metal-enclosed switchgear for indoor distribution rooms.

• Metal-clad withdrawable switchgear: such as KYN28-12 and KYN61-40.5, used in power plants, substations and heavy industrial plants for control, protection and frequent operation.

Low-Voltage Switchgear

Low-voltage (LV) switchgear distributes power at 380 V or 660 V, 50 Hz/60 Hz. The two main construction styles are:

• Fixed-type cabinets (GGD, XL-21): robust, economical and suitable for motor control centers and main distribution boards.

• Withdrawable-type cabinets (MNS, GCK, GCS): modular drawers allow quick replacement of feeders without shutting down the whole system.

Prefabricated Substations

Also known as compact substations or package substations, these integrate high-voltage switchgear, a power transformer and low-voltage switchgear in one weatherproof enclosure. They are widely used for urban grid renovation, residential communities, commercial buildings, industrial parks, railways, airports and temporary construction power.

Distribution Boxes and Cable Branch Boxes

Terminal equipment such as integrated pole-mounted distribution boxes, wall-mounted distribution boxes and European-style cable branch boxes provide the final interface between the distribution network and end users. They offer metering, reactive-power compensation, short-circuit protection and leakage protection in compact enclosures.

Transformers and Power-Quality Equipment

Oil-immersed transformers remain a standard choice for outdoor substations because of their high overload capacity and long service life. Resin-cast dry-type transformers are preferred indoors where fire safety and low noise are critical. Low-voltage capacitor banks improve power factor, reduce reactive-power charges and stabilize grid voltage.

Typical Applications

Complete electrical equipment is used across many sectors:

• Power generation plants and grid substations

• Industrial plants, mining and petrochemical facilities

• Data centers, commercial high-rises and hotels

• Residential communities and urban distribution networks

• Railways, metros, airports and ports

• Renewable-energy plants and energy-storage stations

Benefits of Using Complete Equipment

• Shortened project schedule: factory assembly and testing reduce on-site work.

• Higher reliability: standardized production and type testing minimize commissioning failures.

• Smaller footprint: compact RMUs and package substations save valuable floor space.

• Lower total cost: reduced installation labor, less cabling and faster energization.

• Flexible expansion: modular units can be extended as load grows.

Frequently Asked Questions

What is the difference between a ring main unit and a switchgear cabinet?

An RMU is a compact, ring-network switchgear assembly typically used for cable distribution. A switchgear cabinet is a broader term that includes RMUs, metal-clad withdrawable gear and fixed-type panels.

Is gas-insulated switchgear safe?

Modern gas-insulated switchgear is fully sealed, type-tested and designed with pressure relief and interlocking. Environmentally friendly versions use dry air instead of SF₆.

Can complete equipment be customized?

Yes. Most manufacturers offer customization for voltage level, current rating, protection scheme, enclosure material, degree of protection and automation functions.

Get the Right Power Distribution Solution

Whether you need HV ring main units, LV withdrawable switchgear, compact substations or distribution boxes, selecting the right complete equipment is critical for project safety and efficiency. For technical parameters, drawings and a tailored quotation, feel free to consult us via email.