Insights
Dry-type vs Oil-immersed Transformer — Which to Specify
When to choose a cast-resin dry-type transformer and when an oil-immersed unit, with the efficiency basis per GB 20052-2024.
Both dry-type and oil-immersed transformers step 10(6)kV down to 0.4kV. The choice is mostly about where the unit sits.
Dry-type — SCB18
Cast-resin windings, no oil, fire-safe. Natural or forced air cooling, insulation class F/H. Ideal for indoor installation in buildings, hospitals and data centers where fire safety matters. Meets GB 20052-2024 Grade 1 efficiency. Capacity 100–2500 kVA.
Oil-immersed — S22-M
Hermetically sealed corrugated tank, no conservator, moisture-proof breathing. Lower first cost and better suited to outdoor and utility settings. Also GB 20052-2024 Grade 1. Capacity 100–2500 kVA; vector group Dyn11 / Yyn0.
Decision rule
- Indoor, occupied building, fire sensitivity → dry-type (SCB18)
- Outdoor, utility, cost-sensitive → oil-immersed (S22-M)
- Data center / hospital → dry-type for fire safety, with forced cooling option
Efficiency grade is the same (Grade 1) for both per GB 20052-2024; the difference is installation environment, not energy class. See SCB18 and S22-M.
XSDQ Electric — Lu'an Xinsheng Electric Co., Ltd., brand XSDQ Electric.