Choosing a grain-oriented grade for transformer efficiency class
Core loss, core design and processing affect transformer efficiency. The LG/L values shown are technical reference data, not Baosteel specifications.
The LG/L series on this page are reference grades from the original mill manuals, not Baosteel grades. Baosteel supply grades, properties and specifications are subject to official Baosteel documentation, the quotation and the mill test certificate for the relevant batch.
No-load loss of a transformer comes almost entirely from the core, so the grade you choose sets the efficiency class you can reach. Domain-refined (QH) grades lower the loss further than high-permeability (QG) grades of the same thickness, and thinner strip reduces eddy-current loss.
| Transformer type | Class 1 | Class 2 | Class 3 |
|---|---|---|---|
| Power transformer | LG23QH080 | LG23QH090 · LG23QH085 | LG27QH095 |
| Oil-immersed distribution | LG20QH070 | LG23QH080 · LG20QH075 | LG23QH085 · LG23QH080 |
Typical values of common grades
| Grade | P1.7/50 (W/kg) | J800 (T) |
|---|---|---|
| LG27QH100 | 0.94 | 1.90 |
| LG27QH095 | 0.89 | 1.90 |
| LG23QH085 | 0.79 | 1.90 |
| LG23QH080 | 0.74 | 1.91 |
| LG20QH075 | 0.72 | 1.91 |
Core design, building factor and joint type (step-lap versus butt joint) also affect the final no-load loss. Send us the transformer rating, target class and core drawing and we will propose a grade and a cutting plan.
