Prefabricated substations, also known as box-type substations, are compact power distribution systems designed to supply electricity directly to end users. This integrated solution combines high-voltage switchgear, distribution transformer, and low-voltage power distribution equipment into a single prefabricated enclosure. The equipment is installed inside a moisture-proof, dust-proof, fire-resistant, and fully enclosed steel structure, making it suitable for both indoor and outdoor installations.

The box-type substation integrates voltage transformation and low-voltage distribution functions in one unit, significantly reducing installation space and construction time. It is widely used in urban and rural power grid construction, industrial facilities, commercial buildings, and infrastructure development projects.

Structure Composition

The high-voltage room acts as the power supply side and typically supports incoming voltages of 35kV, 20kV, or 10kV. It includes high-voltage busbars, circuit breakers or load switches, voltage transformers, surge arresters, and related protection equipment.

The transformer room houses the distribution transformer, which is the core equipment of the box-type substation. It performs voltage step-down and ensures stable power supply to downstream loads.

The low-voltage room includes low-voltage busbars, circuit breakers, protection devices, and energy metering equipment. Power is distributed to users through outgoing feeders connected to the low-voltage busbars.

Layout Types

Prefabricated substations are available in triangular and rectangular structural layouts, allowing flexible configuration according to project requirements. Based on high-voltage power supply modes, they can also be classified as terminal type substations and ring network type substations.

Push-pull lifting devices are installed on both sides of the base, facilitating transportation, lifting, and installation. The high-voltage and low-voltage compartments can adopt standard modular structures, screen-mounted designs, or frame-mounted configurations. Standard modular structures provide higher integration, while frame-mounted structures offer a more compact overall size.

Implementation Standards

GB 1094.1-2013 Power Transformers Part 1 General

GB 1094.2-2013 Power Transformers Part 2 Temperature Rise

GB 1094.3-2003 Power Transformers Part 3 Insulation Levels, Insulation Tests and External Air Gaps

GB 3906-2006 3.6kV-40.5kV AC Metal-Enclosed Switchgear and Controlgear

GB/T 11022-2011 Common Technical Conditions for High-Voltage Switchgear and Controlgear

GB 7251.1-2013 Low-Voltage Switchgear and Controlgear Assemblies Part 1 General

GB 14048.1-2006 Low-Voltage Switchgear and Controlgear Part 1 General

GB/T 17467-2010 High Voltage/Low Voltage Prefabricated Substations

Key Features

Compact size and small footprint significantly reduce installation space requirements while allowing flexible deployment in various locations.

Movable design enables easy transportation and relocation according to project demands, improving construction efficiency.

Reasonable structural layout supports triangular or rectangular configurations based on application requirements.

Independent functional compartments simplify maintenance and enable quick replacement of components.

Natural ventilation design effectively reduces operating temperature and enhances equipment reliability.

High enclosure protection level allows operation in various outdoor environments including harsh weather conditions.

Environmental Conditions

Altitude not exceeding 4000 meters above sea level.

Ambient temperature range from -45°C to +45°C.

Relative humidity with daily average not exceeding 95 percent and monthly average not exceeding 90 percent.

For environmental conditions beyond the specified range, technical parameters should be confirmed with the manufacturer before ordering.

Applications

Prefabricated box-type substations are widely used in urban power distribution networks, residential communities, industrial parks, renewable energy projects, commercial buildings, mining operations, rail transit systems, and rural electrification projects. Their compact design and integrated functionality make them an ideal solution for modern power distribution systems.