YAIR Trading
Transformer RFQ Specification Checklist
Build a comparable transformer RFQ using voltage, kVA, vector group, impedance, cooling, losses, accessories, standards and destination data.
A transformer inquiry becomes comparable only when every supplier prices the same electrical duty, installation conditions, accessories, tests and document scope. Use this checklist before asking factories for price.
1. Define the electrical duty before discussing price. Do not begin with only “33 kV transformer.” State rated power, system voltages, frequency, phases, vector group, impedance and tap arrangement. These inputs change the electrical design, materials, dimensions and price.
2. State the real installation environment. A supplier cannot select insulation, cooling and enclosure correctly without the site conditions. Provide the highest and lowest ambient temperature, altitude, humidity or pollution exposure, indoor/outdoor location and available installation space.
3. Lock accessories, tests and documents into the quotation. Two transformer prices are not comparable if one includes protection, test evidence and cable interfaces while the other does not. Attach an inclusion schedule and ask suppliers to mark every deviation.
4. Compare bids on a deviation schedule. Ask each supplier to return the same data sheet with guaranteed values and a separate deviation list. Do not treat silence as compliance. Final compliance depends on the approved specification, drawings, test scope and written order terms.
- Rated power in kVA or MVA and number of units
- Primary and secondary voltage, system frequency and phase
- Vector group, impedance and tap range or tap-changer requirement
- Indoor/outdoor installation, altitude and ambient temperature
- Oil-immersed or dry type, cooling method and enclosure requirement
- Applicable standard, routine/type/special tests and required reports
- Accessories, protection devices, cable boxes and spare parts
- Destination country, port, Incoterm and target delivery date
- Rated power: Required kVA/MVA per unit, quantity and continuous or standby duty.
- Voltage system: Primary/secondary rated voltage, highest system voltage when relevant, frequency and number of phases.
- Connection: Vector group, neutral arrangement and earthing requirement.
- Voltage adjustment: Off-circuit or on-load tap changer, tap range, number of positions and control requirement.
- Impedance: Required percentage impedance and tolerance, especially when units will operate in parallel.
- Ambient temperature range and installation altitude
- Indoor, outdoor, kiosk or compact-substation installation
- Coastal, dusty, humid, mining or industrial environment
- Maximum transport dimensions, lifting limits and foundation constraints
- Required ingress protection or enclosure class where applicable
- Local utility, tender or national deviations from the base standard
- Temperature indicators, pressure-relief device, oil-level indication and valves
- Buchholz relay or other protection according to transformer type and rating
- HV/LV terminals, cable boxes, bushings, marshalling box and control wiring
- Routine test report and any specified type or special tests
- General arrangement, foundation, wiring, nameplate and terminal drawings
- Recommended commissioning spares, two-year spares or project-specific spare list
- Guaranteed no-load and load losses at the stated reference condition
- Noise level, temperature rise and efficiency requirements when specified
- Overall dimensions, transport mass, oil mass and lifting arrangement
- Manufacturing lead time tied to drawing approval and test schedule
- Packing method, moisture protection and transport monitoring if required
- Clear exclusions, deviations, warranty terms and after-sales responsibilities
- Is voltage and kVA enough for a transformer quotation?: No. A reliable quotation also needs frequency, phases, vector group, impedance, tap arrangement, installation conditions, standard, tests, accessories and destination data.
- Should every project automatically claim IEC 60076 compliance?: No. State the applicable edition and any local or tender-specific deviations. Compliance must be supported by the approved design and agreed test documents.
- What photo should I send when replacing an existing transformer?: Send a clear full nameplate photo, overall installation photos, terminal and cable-box photos, footprint dimensions, connection drawings if available, and a description of the load and reason for replacement.
- Can YAIR review an incomplete transformer data sheet?: Yes. Upload the tender, single-line diagram, nameplate or existing drawings. YAIR can organize missing questions before requesting comparable supplier offers.
- International Electrotechnical Commission: IEC 60076-1:2011 - Power transformers, Part 1: General - https://webstore.iec.ch/en/publication/588
- International Electrotechnical Commission: IEC 60076-24:2020 - Voltage regulating distribution transformers - https://webstore.iec.ch/en/publication/30367
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