An amorphous alloy transformer uses a new type of energy‑saving core material that significantly reduces no‑load losses compared to traditional silicon steel transformers. This article explains the characteristics of amorphous alloy, the core structures used in amorphous transformers, and the key technical challenges – along with proven solutions for reliable manufacturing.

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1. What Is Amorphous Alloy Material?

Amorphous alloy is a ferromagnetic material made from metals such as iron, nickel, cobalt, chromium, and manganese, with small additions of boron, carbon, silicon, and phosphorus. The material is produced by ultra‑rapid cooling (at rates of about 1 million °C per second), which freezes the atoms in a disordered, non‑crystalline state – hence the term “amorphous.”

Key Properties

Property	Amorphous Alloy	Conventional Silicon Steel
Atomic structure	Disordered (amorphous)	Ordered (crystalline)
Strip thickness	~0.025 mm	~0.27–0.35 mm
Saturation flux density	1.57–1.59 T	~2.03 T
Recommended design flux density (3‑phase)	1.25–1.35 T	1.55–1.70 T
No‑load loss	Very low (70–80% lower)	Reference value

Therefore, amorphous alloy is ideal for reducing transformer no‑load losses – but it requires careful design because its saturation flux density is lower than silicon steel.

Sensitive to Mechanical Stress

Amorphous alloy is extremely sensitive to tensile and bending stress. Even small mechanical forces increase core loss. Consequently, we must account for this in the core and clamp design to maintain low loss performance.

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2. Amorphous Alloy Core Structures

Amorphous strip comes in limited widths – typically 142mm, 170mm, and 213mm. To build a transformer core, we stack these strips to achieve the required cross‑section. The core cross‑section is rectangular rather than stepped, which differs from conventional silicon steel cores.

2.1 Common Core Configurations

Type	Description	Typical Capacity Range
Three‑phase five‑column	Four wound cores forming five magnetic paths; most common structure	Up to 2500 kVA
Three‑phase planar wound core	Flat wound core arrangement	Smaller distribution transformers

✅ For small distribution transformers (≤500 kVA, 10kV), we commonly use a four‑frame five‑column structure with four wound cores. For larger capacities, we stack eight wound cores in two rows (front and back) to achieve a larger cross‑sectional area – enabling ratings up to 2500 kVA with a single amorphous core.

2.2 Lower Yoke Opening Design

To facilitate coil assembly, the core manufacturer designs the lower yoke as an open, multi‑layer interlaced joint. This opening allows the core to be split so we can slide coils over the legs. The joint must be on the lower yoke – not the upper – because the core cannot withstand pressure or stress after assembly.

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3. Key Design Parameters

Parameter	Typical Value	Notes
Lamination factor	0.82 – 0.86	Depends on core stacking pressure
No‑load loss process coefficient	~1.4	Accounts for manufacturing tolerances
Thickness coefficient (core opening overlap)	1.18 – 1.25	Varies by manufacturer; confirm with core supplier before production

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4. Technical Challenges & Process Solutions

Challenge 1: Fragility & Breakage

Amorphous alloy sheets are brittle and prone to breakage. They shed small metal fragments that can cause insulation failure.

Solutions:

• Handle and transport gently – no impacts, no pressure, no bending.
• During coil assembly, cover the upper end of the coil and insulation with clean cloth or insulating paper to prevent fragments from falling into the windings.
• At the lower yoke staggered joint, use a vacuum cleaner to remove metal dust before applying insulating varnish to both sides of the joint for sealing.

Challenge 2: Core Inversion (180° Turnover)

After we assemble the transformer body, we must turn the entire assembly 180° – but the open lower yoke cannot withstand stress.

Solutions:

• For smaller transformers, we use a crane for direct turnover.
• For larger transformers, we use a special turning table to avoid collision and twisting.

Challenge 3: Clamp Design – Pressure Sensitivity

The clamp must not only hold the core securely, but also protect it from external forces. This is very different from conventional S9 or S11 transformer clamp designs.

Design requirements:

• Insulating plates on both sides and the top/bottom of the yokes, plus both sides of the side columns.
• External steel plate clamping structures for mechanical protection.

Therefore, we include these protective measures in every amorphous transformer design.

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5. Summary of Advantages & Limitations

Aspect	Amorphous Alloy Transformer	Conventional Silicon Steel Transformer
No‑load loss	70–80% lower	Reference
Core material cost	Higher	Lower
Saturation flux density	Lower (1.57–1.59 T)	Higher (~2.03 T)
Design flux density	1.25–1.35 T	1.55–1.70 T
Mechanical sensitivity	High	Low
Manufacturing complexity	Higher	Standard
Best application	Long operating hours (utilities, grids)	General purpose