Choosing a grain-oriented grade for transformer efficiency class
Lower core loss means lower no-load loss. This guide maps Lysteel domain-refined grades to the efficiency classes of China’s GB 20052.
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.
