2500 Kva Oil-filled Transformer

The 2500 kVA Oil Immersed Transformer represents the practical upper limit for standard 400V distribution systems. Delivering a colossal continuous current of approximately 3608 Amps, this unit is the ultimate power solution for mega-scale industrial zones and data center main feeds. Beyond this capacity, engineers typically switch to higher secondary voltages (e.g., 690V) to manage current levels.

As a high-specification 33kv transformer stepping down to 400V, this unit bridges the gap between sub-transmission networks and end-user consumption. It is engineered to handle the dual challenges of massive low-voltage current output and high-voltage dielectric stress.

Operating at 33,000 Volts requires a completely different insulation strategy compared to standard 11kV units.

• Impulse Withstand (BIL): The HV windings of this 33kv transformer are designed to withstand lightning impulses of up to 170 kV (Basic Impulse Level). This involves using high-grade crepe paper with graded insulation thickness and specialized corner rings to prevent electrical breakdown at the winding edges.
• Tap Changer Robustness: The off-circuit tap changer is upgraded to a heavy-duty rotary type capable of handling the higher potential difference between taps, ensuring safe voltage regulation even in unstable 33kV grids.

High voltage 33kV porcelain bushings on 2500 kVA transformer

for 170kV BIL insulation withstand.

The defining characteristic of the 2500 kVA unit is its low-voltage output. Handling 3608 Amps requires structural innovation:

• LV Bushing Arrangement: Standard porcelain bushings are insufficient. We utilize heavy-duty monoblock resin bushings or solid copper palms integrated directly into a busbar throat. This design minimizes contact resistance, which is critical because even a micro-ohm of resistance at 3600A generates significant heat.
• Stray Flux Control: To prevent the tank from acting as a heating element due to the massive magnetic field, the interior is lined with magnetic flux shunts made of high-permeability silicon steel.

• Grid Substations: Stepping down from a 33kV sub-transmission ring directly to 400V for local distribution.
• Heavy Metallurgy: Powering electric arc furnaces or rolling mills where load fluctuations are extreme.
• Hyperscale Data Centers: Serving as the main block transformer, often paired in an N+1 configuration.
• Mining Operations: Due to the 33kV input, this unit is ideal for mines where power is transmitted over long distances at higher voltages to reduce line losses before being stepped down at the load center.

2500kva-mining-power-transformer

2500 kVA oil immersed transformer powering heavy mining

excavators in an open pit mine.