Toroidal Core: Inner Diameter 10 mm to 150 mm

Q: What is the advantage of a toroidal core over other shapes in current transformers?

Toroidal cores offer low magnetic leakage, high efficiency, and symmetrical flux distribution, reducing external interference and improving measurement accuracy in differential applications.

Q: How do I select the right material for a toroidal core?

Choose based on frequency range, saturation flux, and core loss requirements: ferrite for high frequencies, powdered iron for medium frequencies, and amorphous alloys for high efficiency at power frequencies.

Q: Can toroidal cores be used in high-temperature environments?

Yes, with materials rated for high temperatures (e.g., certain ferrites up to 125°C) and proper insulation, but performance may degrade if limits are exceeded.

Component Specifications

Definition

A toroidal core is a closed-loop magnetic core with a toroidal (doughnut) shape, typically made from ferromagnetic materials like ferrite, powdered iron, or amorphous alloys. In differential current transformers, it serves as the magnetic circuit that concentrates the magnetic flux generated by primary and secondary windings, enabling accurate current sensing, galvanic isolation, and common-mode noise rejection. Its symmetrical design minimizes external magnetic interference and leakage flux, making it ideal for sensitive measurement applications.

Working Principle

The toroidal core operates on electromagnetic induction principles. When alternating current flows through the primary winding wrapped around the core, it induces a magnetic flux within the core. This flux, proportional to the current, links with the secondary winding, inducing a voltage that can be measured to determine the current. In differential configurations, it compares currents from multiple sources to detect imbalances, such as ground faults or leakage currents, by canceling out common-mode signals while amplifying differential signals.

Materials

Common materials include: Ferrite (e.g., MnZn or NiZn for high-frequency applications up to MHz range), Powdered Iron (for lower frequencies and high saturation flux density), Amorphous Alloys (e.g., Metglas for high efficiency and low core loss), and Silicon Steel (for power frequency applications). Material grades vary based on permeability, saturation flux density, and core loss specifications.

Technical Parameters

Parameter	Typical range	Notes & selection driver
Height	5 mm to 50 mm
Core Loss	< 100 mW/cm³ at 100 kHz, 200 mT
Insulation	Class B or higher (130°C)
Permeability	2000 to 15000 μ (typical)
Core Material	Ferrite (e.g., N87, PC40)
Inner Diameter	10 mm to 150 mm
Outer Diameter	20 mm to 200 mm (typical range)
Operating Temperature	-40°C to +125°C
Saturation Flux Density	300 mT to 500 mT

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

Standards

ISO 9001, IEC 61869, DIN EN 50178

Parent Products

This component is used in the following industrial products

Differential Current Transformer

A current transformer that measures the difference between currents in two conductors, used for ground fault detection.

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Engineering Analysis

Risks & Mitigation

Core saturation leading to measurement errors
Mechanical damage from improper handling
Thermal runaway under overload conditions
Incorrect material selection causing frequency mismatch

FMEA Triads

Trigger: Overcurrent or DC bias in the primary winding
Failure: Core saturation, resulting in nonlinear output and inaccurate current measurement
Mitigation: Design with adequate core size and material saturation margin, use current limiters or bias compensation circuits

Trigger: Physical stress or cracks in the core material
Failure: Increased core loss, reduced permeability, and potential short circuits in windings
Mitigation: Implement strict quality control during manufacturing, use protective coatings, and avoid mechanical shock during installation

Trigger: High ambient temperature or poor ventilation
Failure: Thermal degradation of core material and insulation, leading to performance drift or failure
Mitigation: Ensure proper heat dissipation, select high-temperature-rated materials, and monitor operating conditions

Industrial Ecosystem

Compatible With

Typical Suppliers & Equivalents

Compliance & Inspection

Tolerance

±5% for magnetic parameters (e.g., permeability), ±2% for dimensional specs under standard conditions

Test Method

Testing per IEC 61869 for current transformer accuracy, including ratio error, phase displacement, and temperature cycling; material analysis via B-H curve measurement and core loss testing

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

Check the legal entity, factory address, ownership, certifications, and direct contacts.

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

Manufacturers of Toroidal Core

1 company lists this product among what they make. Company figures are quoted from each company's own website; every card states where the relationship came from.

Coilcore

Guangzhou, Guangdong, CN

Also makes: Inductor/Transformer, Current Transformer, Power Transformer and 5 more

Listed on the company's own website · profile compiled by CNFX from public sources

Listed there as: “Toroidal Core Flat Wire Inductor”
View source page ↗ coilcore.com · checked 2026-08-30

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Manufacturer listings support early research and capability understanding. They are not certification, ranking, or transaction guarantees.

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

What is the advantage of a toroidal core over other shapes in current transformers?