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Prefabricated Substation Buyer Guide

Define whether a prefabricated substation quotation includes the MV equipment, transformer, LV board, enclosure and auxiliary systems, or only part of the package.

Prepared by: JCON ELECUpdated:

Short answer

First define the package boundary: complete MV-transformer-LV assembly, separately supplied equipment, or enclosure only. Transformer capacity alone cannot determine the quotation. Confirm system diagrams, equipment interfaces, heat dissipation, access, transport and site responsibilities together.

Factory production of distribution equipment for substation packages

Quote one coordinated package with explicit interfaces

Identify who supplies each main item and who connects it. A transformer datasheet, enclosure drawing and LV feeder list should refer to the same project revision.

  • Separate MV units, transformer, LV boards, enclosure and auxiliary systems in the schedule.
  • Identify internal connections, earthing, control supply, lighting, heating and ventilation.
  • Distinguish factory inspection from site installation and commissioning.

Substation quotation boundaries to distinguish

ItemComplete-package reviewPartial-supply review
Main equipmentList MV, transformer and LV configurationsIdentify equipment supplied by other parties
InterfacesConfirm internal connections and auxiliary systemsAllocate every electrical and mechanical interface
Site workState foundation, unloading and commissioning exclusionsState who assembles, connects and tests on site

Information to confirm

System diagramMV/LV SLD, voltage, frequency, fault duty, earthing and equipment quantities.
TransformerCapacity, ratio, type, connection, impedance and project datasheet requirements.
Distribution equipmentRMU/MV functions, LV main and outgoing circuits, protection and specified brands.
Enclosure and climateLayout, access, IP requirements, ambient/altitude, heat dissipation, corrosion and noise constraints.
Transport and civil interfacesShipping sections, dimensions/weight, lifting, route constraints, foundation and cable openings.
Inspection and deliveryApplicable standards/editions, assembly evidence, FAT, site responsibilities, packing and named delivery location.

Related equipment

Prefabricated Substation

Coordinated MV, transformer and LV package boundaries for project review.

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Ring Main Unit (RMU)

Compact incoming and transformer feeder units with specified protection and accessories.

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Low Voltage Switchgear

Main distribution, outgoing feeders and auxiliary power configured to the SLD.

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Compare quotations on the same basis

Included equipmentDo not compare an enclosure-only price with a coordinated equipment package.
Thermal and access basisReview the actual equipment layout, environmental assumptions and maintenance access, not enclosure dimensions alone.
Connection and testing scopeList internal cables/bus links, protection settings, FAT records and site tests separately.
Delivered costSeparate packing, inland/international freight, unloading, site services and exclusions.

Frequently asked questions

Is transformer capacity enough to quote a substation?No. MV/LV configurations, transformer requirements, enclosure, environment, interfaces and delivery scope also affect the package.
Does a package automatically include civil works and commissioning?No. The offer must explicitly allocate foundations, unloading, installation, external connections and site commissioning.
Does an enclosure photo prove complete-substation compliance?No. Review the actual configuration, applicable standards, documents and verification scope. A representative production image is not a test certificate.

Sources and scope

JCON ELEC provides this checklist for package coordination. The IEC source describes prefabricated-substation scope; it is not a certificate for any pictured equipment. Final configuration and site suitability require project review.

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Send your drawings and requirements

Share the available SLD, equipment list, project requirements and destination. Mark unresolved points so assumptions can be listed in the proposal.

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