The Bottom Line: An Amorphous Core Cuts No-Load Loss by 60–70% — and It Pays Off Only in Low-Load, Around-the-Clock Duty
Here is the answer up front. An amorphous-core (S15/SH15) distribution transformer cuts no-load loss by roughly 60–70% versus a conventional CRGO (cold-rolled grain-oriented) silicon-steel core, because the core is wound from an ultra-thin ~0.025 mm iron-based metallic-glass ribbon whose core loss per kilogram is far lower than silicon steel. The trade-off is real: an amorphous unit typically costs 20–30% more and is physically larger and heavier, because amorphous alloy saturates at a lower magnetic flux density. The premium pays off only where the transformer runs lightly loaded around the clock — rural feeders, solar/PV step-up duty, and standby units — because no-load loss is the one loss that runs 24/7/365 whether or not you draw load.
Key Takeaways
- Amorphous only cuts no-load (iron) loss — it does not change load (copper) loss, so the benefit shrinks as your load factor rises.
- Expect 60–70% lower no-load loss versus a CRGO core at the same kVA, at a 20–30% higher price and a larger, heavier tank (industry experience, as of 2026).
- Payback is driven by load factor, not kVA — it pays off in low-load, 24/7 duty and usually loses in high-load or peaking duty.
- Specify S15/SH15 against GB 20052-2020 Grade 1 and hold the supplier to a no-load-loss guarantee on the test report, not the brochure.
- Best applications: rural distribution networks, solar farm step-up, standby/backup and lightly loaded industrial feeders.
What Is an Amorphous Core? The Material Science in One Paragraph
Conventional transformer cores are built from CRGO silicon steel — cold-rolled grain-oriented electrical steel, laminated in sheets around 0.23–0.35 mm thick, with an oriented grain structure that lowers loss in the rolling direction. An amorphous core replaces those sheets with a metallic glass: an iron-based alloy (Fe-Si-B) that is cooled so fast from the melt that it never forms a crystal structure. The result is a ribbon only about 0.025 mm thick — roughly one-tenth the thickness of CRGO. Three physical properties make it lose less energy: the extreme thinness cuts eddy-current loss (which rises with the square of thickness); the absence of crystal grain boundaries cuts hysteresis loss; and the alloy's higher electrical resistivity further suppresses eddy currents. The combined effect is the headline number — no-load loss 60–70% lower than an equivalent CRGO core.
How Much Does an Amorphous Core Actually Save? Separating No-Load Loss From Load Loss
A transformer has two loss components. No-load loss (also called iron loss or core loss) is the energy the core consumes just to stay magnetised — it is present the moment the transformer is energised, at full load or no load, and it is the loss an amorphous core attacks. Load loss (copper loss, I²R) comes from current flowing through the windings and rises with the square of the load; an amorphous core does nothing to it. This distinction is the whole economics of the decision. Because no-load loss runs 24/7/365 while load loss runs only when you actually draw power, a transformer that sits lightly loaded most of the day wastes a disproportionate share of its lifetime energy as no-load loss — exactly the situation where the amorphous premium pays off. For the full breakdown of how the S11/S13/S20 grades rank these two losses, see our S11 vs S13 vs S20 loss-grade guide.
Why Does an Amorphous Transformer Cost More and Weigh More? The Saturation Trade-Off
The penalty is physical, not commercial. Amorphous alloy has a lower saturation flux density — roughly 1.5–1.6 T versus about 1.9–2.0 T for grain-oriented silicon steel — which means the core must be built with more cross-sectional area to carry the same magnetic flux. A bigger core means a bigger tank and more steel, and the amorphous ribbon is also brittle, which makes it harder to cut and wind than ductile silicon steel. The practical result at the quotation level is the figure quoted up top: an amorphous-core unit typically prices 20–30% above a CRGO unit of the same rating and is larger and heavier (industry experience, as of 2026). That size and weight penalty matters when the unit must fit an existing bay, a compact substation, or a shipping container — the same size-versus-value trade-off you make on any transformer purchase, which we unpack in the total cost of ownership guide.
When Does the Premium Pay Off? A Load-Factor Rule of Thumb
The decision turns on load factor — the ratio of average load to rated capacity over the year. Here is a practical rule of thumb:
- Low load factor (below ~30%) — rural feeders, solar/PV farms (which generate only in daylight and derate with weather), standby and backup units: no-load loss dominates the energy bill, and an amorphous core typically recovers its 20–30% premium in 2–5 years of energy savings (industry experience, as of 2026).
- Medium load factor (~30–60%) — the two losses are comparable; the choice depends on your electricity tariff and how you value the first cost versus the running cost.
- High load factor (above ~60%) — peaking or continuously loaded industrial transformers: load loss dominates, and a high-efficiency CRGO unit (S13/S20) usually gives better value per dollar.
Because no-load loss is a flat, continuous drain, the economics are easy to model: take the no-load-loss saving in watts, multiply by 8,760 hours per year and your tariff, and compare it against the one-time price premium. If you want to size the unit and build a first-pass equipment list before you price it, the engineering toolbox does both in one pass.
Where Amorphous Cores Do Not Pay Off: High-Load and Peaking Duty
Be clear-eyed about the counter-case. On a transformer that runs heavily loaded most of the time — a factory's main supply, a data-centre feed, or a continuous-process transformer — the load loss dwarfs the no-load loss, so the amorphous premium buys almost nothing on the energy bill while adding size, weight and cost. In those installations a CRGO core at a high efficiency grade (S13 or S20) is the better purchase. The amorphous option also underperforms where first cost and physical size are the binding constraints, because it is both more expensive and bulkier. The rule is not "amorphous is better" — it is "amorphous is better for a specific loss profile." Match the core to the duty, not the brochure.
What Standards and Grades Apply? S15, SH15 and GB 20052-2020 Grade 1
In the Chinese grading system that most QDTB customers specify against, the amorphous-core designations are SH15 (oil-immersed) and SCBH15 (dry-type cast resin), where the “H” marks the amorphous-alloy core and “15” is the loss-grade number. At the efficiency-regulation level, GB 20052-2020 sets three energy-efficiency grades for distribution transformers, and the Grade 1 (highest-efficiency) tier corresponds to amorphous-core no-load-loss levels. The dedicated product standard is GB/T 25446 (oil-immersed amorphous-alloy-core distribution transformers), which sits alongside the general IEC 60076 performance requirements that apply to any transformer. When you specify, cite the grade, not just the word “amorphous” — “SH15, meeting GB 20052-2020 Grade 1” is an unambiguous, testable requirement.
How to Specify an Amorphous-Core Transformer in Your RFQ
To get a clean, comparable quote, pin down these four things:
- State the grade, not the material — “SH15 amorphous core, GB 20052-2020 Grade 1” (or the equivalent IEC loss level) so the no-load-loss target is objective.
- Demand the no-load-loss guarantee in watts and require it on the routine test report — the whole point of amorphous is the no-load loss, so verify it, exactly as you would for any loss grade (see the S11/S13/S20 guide).
- Confirm the size and weight penalty — request outline dimensions and mass up front, because the larger amorphous tank can break an existing bay or a container-load plan.
- Model the payback before you commit — run the no-load-loss saving against your real load factor and tariff; if the payback is beyond ~5 years, a CRGO S13 unit is usually the better buy.
Once the loss profile is settled, use the engineering toolbox to size the unit and generate a first-pass equipment list, then send QDTB the specification with the grade written in — that is the fastest way to a clean, testable quote.
Sources / 资料来源
- Source: GB/T 25446 — Oil-immersed amorphous-alloy-core distribution transformers (product standard for SH15 units).
- Source: GB 20052-2020 — Minimum allowable values of energy efficiency and energy efficiency grades for power transformers (Grade 1 corresponds to amorphous-core no-load-loss levels).
- Source: IEC 60076 — Power transformers (general performance requirements).
- Source: Standard material reference — amorphous alloy saturation flux density ≈1.5–1.6 T vs grain-oriented silicon steel ≈1.9–2.0 T; amorphous ribbon ≈0.025 mm vs CRGO ≈0.23–0.35 mm.
- Source: Industry experience — QDTB amorphous- vs CRGO-core price, size and payback comparison for distribution transformers (as of 2026).