4000 kVA Oil-Immersed Distribution Transformer

4000 kVA Oil-Immersed Distribution Transformer is specified for 4000 kVA (4 MVA) oil-immersed distribution service. It steps 33 kV / 35 kV networks to 0.6 kV / 0.69 kV / 0.8 kV loads. It uses ONAN (Natural) or ONAF (Forced Air) cooling. Engineering details address grid Integration for Renewable Energy, construction, application context, and electrical data for project selection.

Grid Integration for Renewable Energy

For this 4000 kVA rating, grid integration for renewable energy affects how the transformer is selected, protected, and operated in the field.

• Is specifically engineered as a Step-Up Unit for utility-scale photovoltaic (PV) power plants.
• Unlike standard distribution transformers that step down voltage, this rating functions in reverse, boosting the low voltage output from central inverters (typically 600V - 800V) up to medium voltage (33kV or 35kV) for grid transmission.
• As a specialized solar transformer, it is designed to operate under the harsh, cyclic loading conditions of solar farms.
• It features a robust structural design capable of handling the "pulsed" nature of solar energy, where loads fluctuate rapidly with cloud cover, without suffering from thermal fatigue.

Dual-Winding Configuration (Split-Winding)

The dual-winding configuration (split-winding) details below highlight design choices that matter during continuous distribution service.

• Efficiency in solar farm layout is key.
• A defining feature of the 4000 kVA model is the option for a Dual Low-Voltage (LV) winding configuration (e.g., Dy11y11 vector group).
• The Logic: This allows two separate 2.0 MW inverters to be connected to a single solar transformer.
• The Benefit: By galvanically isolating the two LV inputs, we minimize the circulating currents between inverters and significantly reduce the balance of system (BOS) costs by cutting down on trenching and cabling requirements.

Environmental Endurance & Efficiency

These environmental endurance and efficiency points connect the electrical rating with grid conditions, downstream equipment, and maintenance expectations.

• Solar farms are often located in deserts or high-radiation zones.
• Outdoor Resilience: As a rugged oil filled transformer, the tank is coated with C4 or C5-High class UV-resistant paint to withstand decades of direct sunlight.
• The cooling system is oversized to function effectively even at ambient temperatures of 50°C.
• Night-Time Efficiency: Since solar plants generate zero revenue at night, "No-Load Loss" (Iron Loss) is a critical economic metric.
• The design uses high-permeability laser-scribed silicon steel to minimize core excitation power, ensuring the transformer doesn't drain profits during the night.

Protection & Connectivity

These protection and connectivity points connect the electrical rating with grid conditions, downstream equipment, and maintenance expectations.

• HV Connection: Typically fitted with an IP54 Cable Box suitable for terminating large cross-section XLPE cables coming from the MV switchgear.
• Internal Protection: Equipped with a Buchholz Relay and Pressure Relief Device (PRD) with trip contacts.
• In the event of an internal arc fault, these devices instantly isolate the transformer to prevent fire risks in remote solar fields.

Typical Application Context

Application guidance links the transformer rating with the substations, industrial loads, and site conditions where it is normally used.

• Utility-Scale Solar Parks: Connecting central inverters to the 33kV collector ring.
• Energy Storage Systems (BESS): Managing the bi-directional power flow for large battery containers (4MWh+) providing frequency regulation services.
• 4000 kVA oil immersed step-up transformer installed in a utility-scale solar PV power plant.

Electrical and Mechanical Data

The electrical data summarizes the main values needed for project comparison and project comparison.

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