1. Identify the actual electrical interface
Record the generator terminal voltage and frequency, transformer low-side and high-side windings, winding duty, grounding arrangement and breaker position. Do not assume a transformer's tertiary winding can deliver the main-winding MVA, or that similar MW equipment shares a compatible voltage.
| Equipment | Required comparison | Records to request |
|---|---|---|
| Generator | kW/MW, kVA/MVA, power factor, voltage, frequency, duty, net/gross basis | Nameplate, capability/rating data, scope, hours and tests |
| GSU transformer | MVA/cooling, voltages, vector/grounding, impedance/base, taps, BIL | Matching nameplate, drawings, factory/field tests and condition history |
| Circuit breaker | Rated voltage, continuous current, fault duty, frequency, controls and installed position | Specific model/rating data, duty requirements, drawings and tests |
2. Compare MW and MVA on the same duty basis
For a preliminary calculation, MVA = MW ÷ power factor. A 20 MW requirement at 0.90 power factor is approximately 22.22 MVA before any design allowances. Record auxiliary loads, site conditions, operating mode and the cooling basis separately; the calculation does not select or certify a transformer.
3. Resolve frequency and winding mismatches before quotation
A published turbine family may support 50 Hz and 60 Hz configurations, but the specific generator, gearbox, controls and auxiliaries determine the offered package. Likewise, a 13.8 kV generator does not directly match a 34.5 kV transformer low-side winding without a defined interface. Ask for the actual unit records and any conversion engineering scope.
4. Review generator-source and system-source breaker duties
Provide the breaker position, operating duty and the project's fault/protection study. The generator and transformer interface has specific fault-clearing requirements; the breaker must meet the applicable duty rather than only a matching nominal voltage.
5. Separate equipment evidence from release and commissioning
Tie the quotation to the same physical equipment, condition records, included scope and acceptance tests. Separate current allocation, refurbishment/completion, dismantling, shipment, site delivery and commissioning milestones. Send the J&J listing references with your controlling specification to Tommy for the commercial and technical package.
Common questions
Written quotes and supporting records control unit-specific ratings, availability, condition, price, and delivery.
Will matching turbine and transformer MW labels establish compatibility?
No. Compare real and apparent power, actual voltages, frequency, winding duty, grounding, impedance, controls and protection requirements against the same project design.