S11 20kV Oil-Immersed Distribution Transformer

Product Overview

The S11 series 20kV oil-immersed distribution transformer adopts the S11-M fully sealed corrugated-tank construction: the oil conservator is eliminated, oil volume changes are compensated automatically by the elasticity of the corrugated tank walls, and the core-and-coil assembly is isolated from air to prevent oil degradation. The unit is maintenance-free under normal operation and requires no core drying or inspection after transport. Connection group is Dyn11, reducing harmonic impact on the grid. Dual-voltage (20kV/10kV) input with a changeover switch is available on request.

Key Features

• Core built from high-quality cold-rolled grain-oriented silicon steel: low no-load loss and current, compact binding, low noise;
• Oxygen-free copper windings; layer or helical LV structure depending on rating;
• Fully sealed, no core lifting, maintenance-free;
• Optional 20kV/10kV dual-voltage wiring switched via tap-changeover link.

Service Conditions

• Ambient temperature: up to +40°C, down to -25°C; altitude ≤ 1000 m;
• Max. monthly average relative humidity 90% (20°C);
• Indoor or outdoor installation free of fire, explosion, heavy pollution, chemical corrosion and severe vibration.

Technical Parameters

Voltage combination: HV 20kV ±5%, LV 0.4kV; connection group Dyn11. Insulation level (20kV class): power-frequency withstand 55kV, lightning impulse full wave 125kV (peak).