Selection Guide
Selection Guide — Distribution Transformer
How to choose between dry-type SCB18 and oil-immersed S22-M, and how to size the capacity for a 12kV/0.4kV substation.
This guide helps you pick the right distribution transformer for a 12kV/0.4kV substation.
Step 1 — Dry-type or oil-immersed?
- SCB18 (cast-resin dry-type): fire-safe, indoor, GB 20052-2024 Grade 1 — buildings, hospitals, data centers
- S22-M (oil-immersed, sealed): lower cost, outdoor, Grade 1 — grids and industrial outdoor sites
Step 2 — Size the capacity
Estimate apparent power S (kVA) ≈ total kW / 0.8 at power factor ≈ 0.8. Pick the next standard rating: 800 / 1000 / 1250 / 1600 / 2000 / 2500 kVA. Leave 20–30% headroom for future load.
Step 3 — Confirm connections
Primary 10 kV or 6 kV (±2×2.5%); secondary 0.4 kV; vector group Dyn11 for three-phase distribution.
See SCB18 and S22-M for rated parameters.
XSDQ Electric — Lu'an Xinsheng Electric Co., Ltd., brand XSDQ Electric.