Quick answer: Transformer price is driven by active materials, losses, impedance, insulation level, tap changer, cooling, accessories, tests, transport limits, warranty and delivery—not kVA or MVA alone.
Information required before selection
Before deciding that one quotation is high or low, normalise the technical and commercial scope.
- Guaranteed losses and evaluation method
- Voltage ratio, insulation level and winding arrangement
- Impedance and short-circuit withstand requirements
- Conductor material and thermal design
- OLTC/off-circuit taps and control scope
- Cooling equipment, redundancy and noise limits
- Bushings, monitoring, protection, fire/corrosion treatment and spares
- Type/special tests, shipping dimensions, delivery and warranty
Technical selection framework
| Review area | What the buyer should confirm | Why it changes the supply |
|---|---|---|
| Core and windings | Review material, flux/current density and loss guarantees. | Lower guaranteed losses generally require more or higher-grade active material. |
| Insulation | Compare BIL/LI, power-frequency levels, clearances and bushings. | Higher system and insulation duties increase size and component cost. |
| Impedance | Confirm guaranteed value and tolerance. | Impedance affects winding geometry, fault current and short-circuit forces. |
| Tap changer | Compare type, range, steps, manufacturer and controls. | OLTC equipment and control are substantial cost and maintenance items. |
| Tests | Separate routine, type, special and third-party witness tests. | Test scope can add engineering time, laboratory use and schedule risk. |
| Logistics | Review total/transport weight, sectioning, port route and site assembly. | Large-unit transport can dominate the delivered cost. |
Recommended review sequence
- Create a compliance comparison.
- Normalise guaranteed values and scope.
- Identify deviations that reduce cost but increase project risk.
- Separate equipment, testing, logistics and services.
- Evaluate lifecycle losses and reliability as well as purchase price.
Common RFQ mistakes
- Comparing price per MVA without matching voltage and scope.
- Ignoring loss guarantees and capitalised-loss evaluation.
- Treating different tap changers as equivalent.
- Comparing FOB equipment price with an offer including tests, spares or site service.
What a quotation package should contain
The price evaluation should include a technical compliance matrix, guaranteed losses, accessory/test scope, delivery basis, document schedule, exclusions and the cost effect of each accepted deviation.
Need equipment matched to your project?
Project-based example
For high-voltage transformer comparisons, two offers can differ significantly while both show the same MVA. Insulation levels, tap changer, losses, accessories, short-circuit design and test scope must be aligned before judging the price.
Standards note: Use IEC 60076 or the specified national standard together with the project data schedule. Standards define requirements; they do not make two differently scoped offers commercially equivalent.
