For a 33kV, 18 MVA Wilson Power Solutions transformer (or similar 16/20 MVA class power transformers), the oil quantity and oil pit capacity are essential design aspects for fire safety and environmental protection

 For a 33kV, 18 MVA Wilson Power Solutions transformer (or similar 16/20 MVA class power transformers), the oil quantity and oil pit capacity are essential design aspects for fire safety and environmental protection.

1. Transformer Oil Quantity (Estimated)

Approximate Oil Volume: For an 18 MVA, 33/11kV or 33kV class transformer, the total oil quantity generally ranges between 5,000 and 9,000 liters, depending on the tank design (radiator type vs. corrugated), tap changer type, and cooling method (ONAN/ONAF).

3CX 300 SQMM XLPE Cable: The cable itself is dry and does not contribute to the transformer oil volume. However, the HV/LV cable boxes might be filled with a small amount of oil, which is negligible compared to the main tank volume. 

2. Oil Pit Capacity (Soak Pit)

Requirement: An oil soak pit must be installed below the transformer to accommodate spills.

Capacity Requirement: As per IEC/Indian Standards (IS 1646), the soak pit must hold at least 100% of the total oil volume of the transformer.

Volume Recommendation: For a 9,000-liter transformer, a minimum capacity of 9,000 liters + 10% safety margin is recommended for a secure design.

Drainage: The pit must contain a layer of gravel/pebbles (approx. 40mm size, 300mm thick) to prevent fire spread. 

3. Summary Table

Item Estimated Value

Transformer Power 18 MVA

Voltage Class 33 kV

Estimated Oil Volume ~5,000 - 9,000 Liters

Oil Pit Capacity ≥ 100% of Total Oil Volume (Minimum)

Disclaimer: The precise oil quantity must be confirmed from the specific transformer’s General Arrangement (GA) drawing provided by Wilson Power Solutions, as design variations (e.g., using ester oil) will change the quantity.