To request a custom oil immersed transformer, provide the supplier with the electrical rating, primary and secondary voltages, frequency, installation conditions, cooling and oil requirements, applicable standards, and delivery destination. These details allow the supplier to assess the design, identify missing information, and prepare a comparable quotation. A useful RFQ also states the required accessories, documentation, inspection expectations, and project schedule. If some specifications are not yet confirmed, mark them as provisional rather than leaving them ambiguous.
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This guide is for electrical contractors, equipment distributors, utilities, industrial project teams, and procurement professionals sourcing a transformer for a defined application. It is especially useful when a standard configuration does not fully match the site, interface, or project requirements. Buyers can use the checklist below to prepare an RFQ before requesting technical and commercial proposals. Final design suitability should be confirmed by the manufacturer and the project’s responsible electrical engineer.
An oil immersed transformer transfers electrical power between circuits through electromagnetic induction, with its active components immersed in insulating liquid. The liquid provides electrical insulation and helps carry heat away from the windings and core. A complete specification describes not only the transformer’s electrical rating but also how it must connect to, operate in, and be maintained at the installation site. Requirements depend on the application and the regulations or standards specified for the project.
Buyers may need a distribution transformer, a power transformer, or a purpose-designed unit for a particular network or industrial load. The right category depends on the power system and project scope; terminology and rating ranges can vary by market. Oil selection is another design choice: mineral insulating oil is widely used, while ester-based liquids may be considered when project requirements call for different environmental or fire-performance characteristics. Do not assume that one liquid is interchangeable with another without confirming compatibility, design implications, and applicable requirements with the supplier.
Other configurable features can include the tank arrangement, conservator or sealed construction, cooling method, winding material, tap changer, bushings, monitoring devices, and protective accessories. Outdoor exposure, available space, transport constraints, and maintenance access can influence the configuration. The RFQ should identify required features and distinguish them from preferences. This helps suppliers avoid quoting different assumptions for the same project.
Start with the information that determines the transformer’s electrical design, then add the site and commercial requirements that affect configuration and delivery. The figures in the table are illustrative examples only, not a recommended design or a statement of Liye’s available product range. Ask the supplier to confirm whether the proposed values and configuration suit your application.
| RFQ item | What to provide | Illustrative example or clarification |
|---|---|---|
| Rated capacity | Required apparent power, load profile, and any stated overload conditions. | For example, 1000 kVA; confirm the project’s actual demand and design margin. |
| Voltage and connection | Primary and secondary voltages, winding connection, vector group, and neutral requirements. | For example, 11 kV / 0.4 kV; specify the actual system interfaces. |
| Frequency | System frequency and any requirements for operation at other frequencies. | For example, 50 Hz or 60 Hz, as applicable to the installation. |
| Impedance and losses | Required impedance and any project limits or evaluation criteria for losses. | State the applicable specification or request the supplier to propose values for review. |
| Installation and environment | Indoor or outdoor location, ambient conditions, altitude, space, access, and site hazards. | Provide site data rather than relying on generic assumptions. |
| Construction and accessories | Tank preference, cooling arrangement, tap changer, bushings, protection, and monitoring. | List mandatory items separately from optional ones. |
| Compliance and documents | Applicable standards, inspection requirements, drawings, test records, and language. | Name the required standard or project specification; do not leave “compliant” undefined. |
State whether the transformer will serve a utility network, a renewable energy project, a factory, a commercial facility, or another load. Describe operating conditions that could affect the design, such as fluctuating loads, frequent switching, harmonics, or unusual environmental exposure. Provide the available fault level or system data when the project team has it. If data is unavailable, ask the supplier to identify what is needed before design approval.
Also confirm the physical interface: cable or overhead connections, cable entry direction, terminal arrangement, enclosure constraints, lifting points, and access for installation. Provide dimensional or transport limits when they are known. These details can affect the tank and accessory arrangement, so they are more useful early in the RFQ than after a quotation has been accepted. Attach a single-line diagram, site layout, or existing equipment drawing where available.
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Choose specifications by working from the electrical system outward. First confirm the load and network voltages, then define connection and protection requirements. Next assess the installation environment, access, maintenance plan, and any project-specific compliance criteria. Finally, compare proposals on a like-for-like basis, including included accessories, documentation, testing scope, delivery terms, and exclusions.
Two quotations may appear similar while using different assumptions or scopes. Ask suppliers to list deviations and unresolved items, and do not treat an omitted requirement as accepted. If efficiency or lifecycle cost is important, request the relevant loss values and the basis for evaluating them. The project team can then assess purchase price alongside operating priorities without relying on an unsupported generalization.
There is no dependable universal price for a custom transformer because cost depends on rating, voltage levels, materials, accessories, design requirements, testing scope, and delivery terms. Minimum order quantities, if applicable, are supplier- and project-specific, so buyers should request confirmation rather than assume a standard MOQ. Lead time also depends on design approval, material availability, production planning, and inspection or shipping arrangements. Request a quotation that states its validity period, delivery basis, estimated schedule, and the events that start the lead-time clock.
To improve quote accuracy, submit one consolidated specification and identify the quantity, destination, target delivery date, and any staged shipment needs. If you are still comparing technical options, ask for clearly separated alternatives rather than a single price built on unstated assumptions. Confirm whether the quotation includes packing, export documentation, commissioning support, or other services. These details help procurement compare total scope rather than headline price alone.
Evaluate a supplier on its ability to understand the application, explain design assumptions, and respond clearly to technical questions. Request relevant company and product information, a proposed technical datasheet, and a list of documents available for the project. Verify any claimed certifications, standards, test capabilities, and warranty terms against the actual proposal and supporting records. Avoid relying on broad claims that are not tied to the specific equipment being quoted.
Before placing an order, agree on the approved specification, drawing review process, inspection and testing scope, acceptance documentation, packaging, and delivery responsibilities. Confirm who will approve technical changes and how deviations will be recorded. This is particularly important when several stakeholders are involved in procurement, engineering, installation, and operation. A written clarification schedule can reduce the risk of different parties interpreting the order differently.
Liye works with B2B buyers seeking custom oil immersed transformer solutions. Share your electrical parameters, site conditions, project documents, quantity, and delivery destination so the team can review the request and clarify what information is still needed. Where a requirement is not yet fixed, identify it as open for technical discussion. Product configuration, documentation, and commercial terms should be confirmed for each project rather than assumed from a general inquiry.
A strong RFQ defines the transformer’s electrical rating, system interfaces, installation conditions, construction preferences, compliance needs, and commercial scope. The illustrative values in this guide are examples, not a substitute for engineering review or a supplier’s confirmed design. For your next step, prepare a specification sheet, attach available diagrams, mark unresolved items, and ask each supplier to identify assumptions and deviations. Send the complete package to Liye for an initial review and a project-specific quotation.
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