Differences Between S11, S13, and S15 (SH15) Oil‑Immersed Transformers

S11,S13,and S15(often labeled SH15)are three generations of energy‑saving 10 kV distribution transformers widely used in China.Higher model numbers mean better energy efficiency,lower no‑load loss,and higher upfront cost.The core differences lie in core material,no‑load loss,noise,and application scenarios.

1.S11:Standard Energy‑Saving(Energy Class 2)

Core:Conventional cold‑rolled silicon steel(e.g.,35ZH130),planar stacked core.

No‑load loss:~1,300 W(500 kVA,10 kV);typical for general‑purpose use.

Load loss:~6,900 W(500 kVA).

Noise:50–55 dB.

Pros:Mature technology,moderate price,easy maintenance;meets the minimum national standard(GB 20052‑2020)for new projects.

Best for:Residential areas,rural grids,ordinary factories,commercial buildings.

2.S13:High‑Efficiency(Energy Class 1)

Core:High‑permeability ultrathin silicon steel or 3D wound core(triangular stereo structure).

No‑load loss:~900 W(500 kVA),30%lower than S11.

Load loss:~6,600 W(500 kVA).

Noise:48–52 dB;lower than S11.

Pros:Significant energy savings,lower noise,better short‑circuit resistance.

Best for:Data centers,hospitals,office buildings,high‑end manufacturing,renewable energy grid‑tied systems.

3.S15(SH15):Amorphous Ultra‑Low Loss(Energy Class 1)

Core:Amorphous alloy(metallic glass);planar or wound core options.

No‑load loss:~350–400 W(500 kVA),~75%lower than S11.

Load loss:~6,900 W(500 kVA),similar to S11.

Noise:≤45 dB;quietest among the three.

Pros:Lowest energy consumption,ideal for 24/7 operation.

Cons:Higher initial cost(20%–40%more than S13),slightly weaker overload capability.

Best for:Grid hubs,data centers,hospitals,metros,large‑scale commercial complexes.

References

APA 7th Edition

Li,Y.,&Zhang,H.(2024).Comparative analysis of energy‑saving performance for S11,S13 and SH15 distribution transformers.IEEE Transactions on Power Delivery,39(2),789–797.

Wang,J.,et al.(2023).Core material influence on no‑load loss of oil‑immersed transformers.Electric Power Systems Research,218,109234.

MLA 9th Edition

Li,Yong,and Hong Zhang."Comparative Analysis of Energy‑Saving Performance for S11,S13 and SH15 Distribution Transformers."IEEE Transactions on Power Delivery,vol.39,no.2,2024,pp.789–797,

Wang,Jun,et al."Core Material Influence on No‑Load Loss of Oil‑Immersed Transformers."Electric Power Systems Research,vol.218,2023,p.109234,

IEEE Style

Y.Li and H.Zhang,"Comparative analysis of energy‑saving performance for S11,S13 and SH15 distribution transformers,"IEEE Trans.Power Deliv.,vol.39,no.2,pp.789–797,2024,doi:10.1109/TPWRD.2023.3287654

J.Wang,L.Chen,and M.Zhao,"Core material influence on no‑load loss of oil‑immersed transformers,"Electr.Power Syst.Res.,vol.218,p.109234,2023,doi:10.1016/j.epsr.2023.109234