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Medium and large oil-immersed distribution transformers for PV, EV, and BESS installations

These are oil-filled transformers used to convert medium-voltage electrical energy (6 kV to 35 kV) to low voltage ranging from 400 V to 800 V, or from low voltage to medium voltage

They can be two-winding or three-winding transformers. They are hermetic transformers, where the electrical active part is enclosed in a sealed tank completely filled with insulating oil. Upon special request, they can be made with a conservator (as non-hermetic). They are designed to work with photovoltaic (PV) systems, electric vehicle (EV) chargers, and energy storage systems (BESS). They can also be used to supply railway traction.

Specifications

Basic electrical parameters:

  • Rated power in kVA: from 250 to 7000

  • Primary rated voltage in kV: 6.3, 10.5, 15.75, 21, 31.5, or others in the range of 10 kV to 35 kV

  • Secondary rated voltage in V: 400, 420, 440, 480, 550, 600, 690, 800

  • No-load voltage regulation: ± 2 × 2.5% or ± 3 × 2.5%

  • Connection group: Dyn5, Dyn11, Dyn5yn5, Dyn11yn11, Dd0, Dd0d0, Yd5, Yd5d5

  • Short-circuit voltage: 4% to 10%

  • Reinforced insulation system

  • Electrostatic screen between HV and LV windings (recommended)

  • Transformer efficiency: in accordance with the EU ECO Directive Tier 2 or individual customer requirements

  • Voltage harmonic level THDu: up to 20% or up to 40%

  • Current harmonic content THDi: up to 5% or up to 10%

  • For other parameters – please contact us to clarify the details.

High-Power Oil Distribution Transformers for PV and EV Installations

The transformer tank, made from flexible steel corrugated walls, ensures tightness and proper cooling of the transformer. Depending on our clients’ requirements, we provide anti-corrosion protection/protective coatings, ensuring resistance and durability for products operating even in the most demanding conditions.

On the transformer cover, there are bushings for the high-voltage (GN) and low-voltage (DN) sides, oil filler, tap changer head, and other equipment agreed upon with the client.

The insulating fluid most commonly used is mineral oil — which can be either inhibited or uninhibited. Alternatively, biodegradable vegetable oil can be used as the insulating fluid; this oil is a mixture of esters of fatty acids derived from plant sources, or synthetic esters of fatty acids can also be applied.

High-Power Oil Distribution Transformers for PV and EV Installations

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