Compact Substation Specification: A Practical RFQ Checklist

A compact substation specification should describe the complete package and its interfaces. Two quotations with the same transformer capacity can include different switchgear, low-voltage equipment, enclosure arrangements and site responsibilities. A clear request for quotation makes those differences visible before the commercial comparison begins.

Define the system and the supplied package

Begin with a single-line diagram showing the incoming supply, transformer and outgoing circuits. State whether the network is radial or part of a ring arrangement, and identify the required switching and protection functions. Ask the supplier to mark the boundary of its supply on the drawing.

Jikai’s European box-type transformer page describes a YB series compact substation integrating high-voltage switchgear, a transformer and low-voltage distribution in one enclosure. Treat that description as a starting point for the equipment schedule, then confirm the exact components and accessories in the offered package.

Build the RFQ around six specification groups

Review the enclosure as part of the system

The enclosure affects ventilation, maintenance access and how operators reach the equipment. Request a general arrangement drawing showing door swings, operating space, cable entries and lifting provisions. For an existing site, provide photographs and measured access restrictions rather than relying on a nominal footprint.

IEC 62271-202:2022 addresses enclosed AC prefabricated substations within its stated scope, including service conditions, rated characteristics, construction and tests. Its public description highlights the effect of the enclosure and installation conditions. Specify the applicable standard and edition in the project documents, and ask for supporting evidence covering the offered assembly.

Identify responsibilities before ordering

List who designs the foundation, supplies external cables, completes earthing, handles unloading and performs commissioning. Confirm whether protection settings, utility witnessing and local approval documentation are included. These interfaces are common sources of quotation differences even when the equipment itself looks similar.

Separate the technical acceptance milestones from the delivery date. A sensible schedule identifies drawing approval, manufacturing release, document submission and any agreed factory inspection. Late changes to cable entry or outgoing feeders can affect an otherwise completed package.

Compare exceptions, not just compliance statements

Ask every bidder for an explicit deviation list. An unqualified “compliant” response is difficult to evaluate if the requested accessory schedule has never been acknowledged. Resolve differences in writing and retain the final equipment list with the purchase order.

Frequently asked questions

Is a box-type transformer the same as a bare transformer?

The term often describes an integrated package. Confirm the actual MV, transformer, LV and enclosure scope rather than relying on the name.

Does the transformer’s kVA define the whole package rating?

No. Enclosure conditions, switchgear and distribution equipment must also satisfy the intended duty.

What should accompany a first inquiry?

A single-line diagram, electrical schedule, site conditions and a clear scope boundary provide a useful basis for a comparable quotation.