Resolve the meaning of 11kV first
An enquiry headed 11kV transformer can omit the most important voltage information. State the network nominal voltage, the required transformer winding voltages and the insulation requirement separately. Do not copy the voltage label from an adjacent switchgear panel into the transformer ratio field.
Ask the utility or project designer for the accepted supply conditions and permitted voltage variation. The supplier can then respond with a proposed ratio and tap arrangement against a defined requirement. A tap range should not be assumed to turn an otherwise unsuitable winding design into the requested product.
Return one completed electrical schedule
| RFQ field | Buyer information | Supplier response to compare |
|---|---|---|
| Supply and frequency | Approved network data and operating range | Proposed winding rating and frequency |
| Secondary supply | Required voltage at the transformer and load constraints | Rated ratio and relevant voltage assumptions |
| Insulation | Project requirement for windings and terminals | Declared levels and applicable test evidence |
| Voltage adjustment | Operating objective and permitted method | Tap positions, adjustment method and limitations |
| Load duty | Initial demand, profile and credible growth | Offered capacity under stated service conditions |
| Connections | Cable or busway arrangement and neutral interface | Terminal drawing and included accessories |
Keep units and definitions visible. A quotation should distinguish a guaranteed value, an offered alternative and information awaiting confirmation. This makes differences between bids reviewable before price becomes the deciding factor.
Treat insulation evidence as a separate question
IEC 60076-3 addresses transformer winding insulation and associated dielectric tests. Its published scope supports asking for the applicable winding and terminal evidence; it does not prove that a particular catalogue model meets the project's requirements. IEC transformer insulation scope.
Agree the applicable edition, amendments and utility requirements in the order. Request the identification of the offered design and the report scope. A sample for another primary voltage or capacity should remain labelled as reference material.
Example: an apparently close catalogue match
Suppose a buyer needs an 11kV primary winding but receives a catalogue sheet labelled 10kV with several tap positions. The buyer should ask for an explicit offered data sheet and technical confirmation of the requested service conditions. It is not enough to calculate that one tap position looks numerically close.
The same review should include secondary voltage under the specified operating duty and the proposed adjustment procedure. If the supplier offers a different arrangement, record it as a deviation with its engineering consequences instead of silently changing the project schedule.
Close the commercial and document scope
Specify quantity, delivery location, handling restrictions and the accessories included with each unit. Distinguish preliminary sample reports from the serial-number-linked records expected at delivery. If several units are ordered, identify whether their terminal arrangements and accessories are identical.
Send the completed schedule and utility information through the transformer quotation page. The oil-immersed transformer range provides product-family context; its listed models do not establish an approved 11kV configuration. Final voltage, capacity, documents and supply scope require technical confirmation.