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How are prefabricated substations constructed? A comprehensive walkthrough of the entire process, from factory fabrication to on-site assembly.

Release time:

2026-05-25

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Abstract

A prefabricated substation, also known as a packaged substation, is, as its name suggests, a conventional substation whose components are housed within one or more prefabricated modules. The entire process can be summarized as follows: Factory-integrated prefabrication, modular design, and rapid on-site assembly. In simple terms, the installation, wiring, and commissioning of primary and secondary equipment—tasks that would normally be performed on-site—are all moved to the factory, leaving only hoisting and final connections to be carried out at the installation location.

Next, we will proceed from Design, factory prefabrication, on-site construction We will break down its entire manufacturing process in three stages.

I. Scheme Design Phase: Plan Modules as if “Building with Blocks”

Before formal production begins, engineers break down the substation into several standardized functional modules, much like assembling building blocks, based on actual power consumption requirements and site conditions.

These modules typically include: High-Voltage Equipment Compartment (such as the KYN28 cabinet), Transformer (core component), Low-Voltage Distribution Cabinet (such as GGD/GCK cabinets), Secondary Equipment Cabin (Control, protection, and communication systems) as well as Reactive Power Compensation Cabin Wait.

The core considerations during design are as follows:

Modular layout : Depending on the site’s topography, these modules can be flexibly configured in a linear layout, an L‑shaped arrangement, or a two‑story stacked configuration, thereby maximizing the efficient use of valuable land resources.

Standardized interface : Electrical connections and communication interfaces between modules all adhere to a unified standard. This lays the groundwork for future plug-and‑play functionality, ensuring rapid and error‑free on-site integration.

II. Factory Prefabrication Phase: Encasing the “Substation” in a Container

This is the most critical stage in the manufacturing process. While on-site land leveling and foundation work are still underway, the substation is already being “assembled” at the factory.

1. Cabin Manufacturing — “A Robust Armor”

The “house” of a prefabricated substation is not an ordinary modular structure; it is a robust, high‑tech enclosure.

Skeleton structure The cabin frame is constructed from high-strength structural steel welded as a single unit, ensuring it remains deformation-free during transportation and lifting; its strength exceeds that of standard shipping containers by a factor of three or more.

Anti-corrosion treatment To withstand decades of exposure to the elements, the cabin’s outer shell is not only constructed from high-quality steel plate but also undergoes… Sandblasting for rust removal, thermal zinc spraying, multi-layer coating With stringent manufacturing processes, its corrosion resistance far exceeds that of standard outdoor equipment.

Thermal insulation Wall panels typically feature a three-layer composite structure—metal sheet, fire‑resistant insulating rock wool or polyurethane, and an interior finish panel—with a thickness comparable to that of a 24‑cm brick wall. This design effectively insulates against extreme cold or heat from the outside, ensuring stable operation of internal equipment.

2. Internal Equipment — “Precision Filling”

Once the cabin is completed, various electrical components are installed—this is the very essence of “factory‑based production.”

Primary equipment installation In the factory’s cleanroom environment, workers securely install equipment such as high-voltage switchgear, low-voltage distribution panels, and transformers within the enclosure according to the drawings, and complete busbar connections between cabinets as well as the installation of primary cables.

Secondary System Integration This is the core of the intelligent substation. All protection, measurement and control, and communication panels are fully assembled at the factory. Cable routing is neat and uniform, with clearly marked wire identifiers, and the construction standards far exceed those of on-site installation.

System integration testing : After all equipment has been installed and wired, the engineer will conduct tests at the factory. Site-wide commissioning They simulate various power system faults to verify that protective relays operate correctly and that signal transmission is reliable. This step ensures that any issues are resolved before the equipment leaves the factory, significantly reducing on-site commissioning time and risks.

Environmental Control System : To ensure that delicate electronic devices can operate comfortably outdoors, the cabin will also integrate Industrial air conditioning, intelligent ventilation, dehumidification, and lighting systems and is centrally managed by an intelligent controller to maintain constant temperature and humidity inside the cabin.

III. On-site Construction Phase: Lifting and Positioning, and “Plug-and-Play”

While the factory is ramping up production, on-site civil engineering work is proceeding in parallel. All that’s required on site is to pour a simple, level concrete foundation and install conduits for connecting incoming and outgoing cables, significantly reducing the workload.

Quick Lifting : Prefabricated modules, manufactured at the factory, are transported to the site on flatbed trailers and then lifted into place using a crane onto pre‑constructed concrete foundations.

“Plug-and-Play” connectivity ：

Inter-module wiring : High-voltage and low-voltage power cables, as well as communication optical cables, between the modules all employ Prefabricated plug-in connector On-site workers simply plug in and unplug a massive power connector, eliminating the need for on-site wire stripping and crimping—making the process both fast and reliable.

One-time wiring : Connect the high- and low-voltage sides of the transformer to the high-voltage compartment and the low-voltage compartment using cables.

Overall acceptance and energization : After all modules have been connected, conduct a comprehensive system integration test for the entire substation. Once confirmed to be functioning properly, proceed with the power‑on application.

Why is this approach the trend of the future?

The manufacturing of prefabricated substations represents a profound transformation, shifting from “on-site construction” to “factory fabrication.”

Construction period shortened : On-site civil construction and factory production can proceed in parallel, thereby shortening the overall construction timeline. More than 50% A 110 kV prefabricated substation can be commissioned in as little as eight months from the start of construction, saving approximately five months compared to the conventional approach.

Higher quality : Manufacturing, installation, and commissioning are carried out in a standardized factory environment, thereby eliminating the adverse effects of on-site weather conditions, dust, and uneven operator skill levels, ensuring greater reliability in equipment processes and quality.

More environmentally friendly : On-site wet work is minimal, significantly reducing construction waste, dust, and noise.

More flexible layout Modular design can better adapt to various complex terrains, with a footprint smaller than that of conventional substations. More than 20% 。

As a full‑chain manufacturer of electrical switchgear and complete equipment, Hunan Electrical Appliance Co., Ltd. We possess mature R&D and manufacturing capabilities in the field of prefabricated substations. We offer end-to-end services, from conceptual design and cabinet sheet-metal fabrication to complete equipment integration and factory‑level commissioning, with flexible configuration options tailored to customer requirements. High-voltage switchgear (KYN28/XGN/HXGN), low-voltage complete switchgear (GGD/GCK/GCS/MNS), and intelligent control systems. , developing a pre-assembled substation solution featuring factory prefabrication and rapid on-site assembly.

For customized solutions or technical consultation, please feel free to call us or visit our facility to discuss potential collaboration.

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