Laminated Core: Component Specs, Materials & Applications

Component Specifications

Definition

A laminated core is a key component in control transformers, constructed from thin, insulated sheets of electrical steel stacked together. This design minimizes eddy current losses by interrupting the path of induced currents, improving efficiency and reducing heat generation in transformer operation. It serves as the magnetic circuit that transfers energy between primary and secondary windings while maintaining precise voltage regulation.

Working Principle

Works by providing a low-reluctance magnetic path for alternating magnetic flux. The laminated structure with insulated layers prevents large circulating eddy currents that would occur in solid metal, reducing energy losses and heat. When AC current flows through transformer windings, it creates a changing magnetic field that induces voltage in adjacent windings via the core's magnetic circuit.

Materials

Electrical steel (silicon steel) sheets, typically 0.23mm to 0.35mm thickness, with insulation coating (C-3, C-4, or C-5 grade). Common grades: M-15, M-19, M-22, M-27, M-36, M-43, M-45, M-47. Silicon content: 2-4.5%.

Technical Parameters

Parameter	Typical range	Notes & selection driver
Core Loss	1.0–2.5 W/kg at 1.5 T, 50 Hz W/kg	Lower values indicate higher efficiency; depends on steel grade and thickness.IEC 60404-2
Permeability	1000–5000 at 1.0 T, 50 Hz dimensionless	Higher permeability improves magnetic flux conduction; varies with grade and processing.IEC 60404-6
Stacking Factor	0.95–0.98 dimensionless	Ratio of effective core area to physical area; higher is better for reducing size.IEC 60404-13
Lamination Thickness	0.23–0.35 mm	Thinner laminations reduce eddy current losses but increase cost.IEC 60404-8-1
Insulation Resistance	≥100 Ω·cm²	Minimum insulation resistance between laminations to prevent interlaminar short circuits.IEC 60404-1
Operating Temperature	-40 to 155 °C	Class F insulation; above 155°C insulation degrades, increasing core losses and risk of failure.IEC 60085
Ambient temperature	-40 to 40 °C	Outside this window: Below -40°C, core becomes brittle; above 40°C, insulation may degrade if combined with high core temperature.
Frequency	50–60 Hz	Outside this window: Higher frequencies increase eddy current losses; above 60 Hz, core loss exceeds specified limits.
Magnetic flux density	1.0–1.7 T	Outside this window: Above 1.7 T, core saturates, causing excessive magnetizing current and overheating.
Core temperature rise	≤ 80 K above ambient	Outside this window: Exceeding 80 K rise accelerates insulation aging and may cause thermal runaway.

Ranges are indicative industry figures for RFQ preparation, not a supplier commitment. Confirm every value and standard with the legal manufacturer before ordering.

Standards

IEC 60404-2, IEC 60404-6, IEC 60404-8-1, IEC 60404-13, IEC 60085, IEC 60404-1

Parent Products

This component is used in the following industrial products

Control Transformer

A transformer that provides low-voltage power for control circuits within motor control centers.

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Engineering Analysis

Risks & Mitigation

Core saturation leading to overheating
Interlamination short circuits
Mechanical damage during assembly
Insulation breakdown at high temperatures
Magnetic flux leakage

FMEA Triads

Trigger: Poor insulation between laminations
Failure: Increased eddy current losses, overheating, reduced efficiency
Mitigation: Quality control of insulation coating, proper handling to prevent damage, thermal monitoring

Trigger: Mechanical stress during assembly
Failure: Distorted magnetic path, increased noise, reduced performance
Mitigation: Precision stacking equipment, controlled clamping force, alignment verification

Trigger: Core saturation from overvoltage
Failure: Excessive heating, waveform distortion, potential insulation failure
Mitigation: Proper transformer sizing, voltage regulation, saturation detection circuits

Compliance & Inspection

Tolerance

±0.1mm on lamination dimensions, ±2% on stacking height, angular tolerance ±0.5°

Test Method

Epstein frame test for core loss, permeability measurement, insulation resistance test, dimensional verification, visual inspection for defects

Procurement Evaluation Criteria

A practical evidence checklist for RFQ preparation and supplier evaluation.

Technical documentation

Request current drawings, revision history, and a signed specification sheet.

Manufacturing capability

Verify equipment lists, process limits, capacity, and representative production evidence.

Inspection readiness

Confirm test methods, calibrated equipment, sampling plans, and traceable reports.

Supplier transparency

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CNFX does not score or rank suppliers. Buyers must verify all claims and documents with the legal manufacturer before ordering.

Manufacturers of Laminated Core

Manufacturer profiles associated with Laminated Core.

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Compiled and source-reviewed by the CNFX editorial team. Each manufacturer above links to the page on that company's own website where the product is listed, with the date we checked it. How we source and review

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Frequently Asked Questions

Why are transformer cores laminated instead of solid?

Lamination reduces eddy current losses by breaking the path for circulating currents. Solid cores would experience significant energy loss as heat due to induced eddy currents from alternating magnetic fields.

What materials are used for laminated cores?

Primarily electrical steel (silicon steel) with 2-4.5% silicon content. The silicon increases electrical resistivity and reduces hysteresis losses. The sheets are coated with insulation to prevent electrical contact between layers.

How does lamination thickness affect performance?

Thinner laminations (0.23mm) reduce eddy current losses more effectively but increase manufacturing cost. Thicker laminations (0.35mm) are more economical but have slightly higher losses. The choice depends on frequency and efficiency requirements.

Data Basis

Editorial classification, named public sources where available, and source-reviewed manufacturer records. See the editorial policy.

Preliminary Technical Classification

This page supports structured research, RFQ preparation, and supplier evaluation. It does not replace buyer-led supplier qualification, standards review, or technical approval.

Laminated Core