Applications
Transformers for utility-scale solar plants
A transformer for a solar power plant spends its life feeding a current waveform that a 50 Hz sine wave model does not describe. Sizing on the nameplate is how plants end up with transformers that run hot from year one.
Solar farm transformer sizing: the inverter, not the nameplate
A 1500 V DC array feeds inverters whose output is rich in harmonics. Harmonic currents increase winding eddy losses, which raise hot-spot temperature, which shortens insulation life. IEEE C57.110 sets out the derating method. We size the transformer so the hot-spot stays inside limits under the real current spectrum, not under a clean sine wave.
PV step-up transformer selection: where the unit sits in the chain
- Array (1500 V DC)
- inverter (0.6–0.8 kV AC)
- inverter step-up transformer
- collection at 12–35 kV
- main step-up transformer
- 110–500 kV grid connection
What we supply for solar
- Inverter step-up transformers: 10–35 kV, 30 kVA to 31.5 MVA, dry-type or oil-immersed.
- Main step-up transformers: 110–500 kV, up to 600 MVA, with low-voltage windings matched to inverter or generator output.
- Auxiliary and station service transformers.
High ambient and desert sites
Many of the highest-irradiance sites run at 45–55 °C ambient, well above the 40 °C maximum that IEC 60076-2 assumes for temperature rise. At 50 °C a transformer rated 3425 kVA at 45 °C delivers roughly 3083 kVA. We derate from the site temperature record, not from a nominal figure.
Specification checklist
- Plant capacity and inverter model
- Grid code and connection voltage
- Site ambient temperature range and altitude
- Solar irradiance and dust profile
- Harmonic spectrum from the inverter datasheet
- Required delivery date and COD
- Applicable standards and any utility prequalification
Do you supply both dry-type and oil-immersed for solar?
Yes. Inverter step-up transformers are commonly dry-type at 10–35 kV; main step-up transformers are oil-immersed. Both are built in our own plants.