35 kV class power transformers for renewable plant step-up substations and 35 kV grid connections — supplied against a project-specific specification.
Because every 35 kV transformer is tied to a specific grid approval, this page describes the configuration and the selection process rather than a fixed catalogue table. Send us the grid approval, the required rating, the cooling class and the site altitude and we will return a technical proposal with the matching nameplate data.
A 35 kV power transformer is the interface between a medium-voltage collection system and the transmission or sub-transmission network. In renewable plants it steps the 10 kV or 35 kV collection voltage up to 35 kV for the grid connection point. Unlike the standard 10 kV distribution units, a 35 kV transformer is always a project-specific item: rating, impedance, vector group, cooling class and the required temperature rise are set by the grid operator's approval.
The principle is the same as any transformer — alternating flux in the core induces the secondary voltage — but the insulation system, the oil volume and the radiator arrangement scale with the higher voltage and power. Cooling moves from ONAN at moderate ratings to ONAF or forced oil/water cooling at the larger ratings, driven by the grid operator's permitted temperature rise. Neutral earthing, on-load tap changer arrangement and the number of cooling fans are all confirmed against the grid approval before manufacture.
| Parameter | Typical value |
|---|---|
| Rated voltage | 35 kV / 0.4 kV, 35 kV / 10.5 kV, 35 kV / 11 kV, or per grid approval |
| Rated power | 2000 / 2500 / 3150 / 4000 / 5000 / 6300 / 7500 / 10000 / 12500 / 16000 / 20000 kVA |
| Rated frequency | 50 Hz (60 Hz on request) |
| Vector group | YNd11 or Dyn11 as required by the grid code |
| Cooling class | ONAN, ONAF or forced oil/water cooling |
| Permitted temperature rise | 55 K (oil) / 55 K (winding) or as approved |
| Tap changer | Off-circuit or on-load, per grid requirement |
| Neutral earthing | Solid or resistance earthing with neutral current device, per grid requirement |
| Enclosure | Outdoor, with radiators and conservator; IP00 as standard with the option of a weather canopy |
| Site altitude | Up to 1000 m without derating; altitude-corrected design above that |
| Compliance | GB 20052-2024, GB/T 6451-2023, GB/T 1094 series, IEC 60076 series |
The grid approval comes first — it fixes the rating, the vector group, the neutral arrangement and the permitted temperature rise, and those determine the physical design. From there, check the transport envelope: a 35 kV transformer is the heaviest single item on any site, and the route from the port or the factory to the substation pad usually constrains the design more than the electrical specification does. Finally, confirm the harmonic duty — with a large inverter or rectifier load, the loss and temperature-rise figures change and derating may be required.
Commonly 2000 kVA to 20000 kVA, in 35/0.4 kV, 35/10.5 kV or 35/11 kV combinations. Because each unit is tied to a grid approval, the rating is confirmed in the technical agreement rather than selected from a fixed catalogue.
ONAN for moderate ratings, ONAF where a lower temperature rise is permitted, and forced oil or water cooling at the highest ratings. The class is set by the grid operator's permitted temperature rise and the site cooling water availability.
Frequently yes, because the grid connection point voltage varies. Where the incoming voltage is stable, an off-circuit tap changer is used instead. The arrangement is confirmed against the grid approval before manufacture.
It has to be declared at enquiry stage. The loss figures, the temperature rise and sometimes the rating itself are affected by harmonic content from a large inverter load, and derating may be required.
By road in the tank's normal shipping condition, or split into tank, radiator and accessories if the shipping envelope requires it. We supply the transport dimensions and the lifting and shipping weights so that your site logistics can be planned before shipment.
GB 20052-2024 for energy efficiency, GB/T 6451-2023 for oil-immersed power transformers and the GB/T 1094 and IEC 60076 series for general requirements, temperature rise, insulation levels and short-circuit withstand.
Send us the rated voltage, rated current or capacity, quantity and destination country, plus any single-line diagram. We reply with a configuration proposal and a quotation — usually within 24 hours of receiving complete technical information.
Request a Quotation+86 186 5877 2666
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sw@xsdq.cc
+86 186 5877 2666