INDUSTRY COMPONENT

Secondary Winding

Secondary winding is the output coil in a current transformer that produces a reduced current proportional to the primary current for measurement and protection.

Component Specifications

Definition
The secondary winding in a current transformer is a precisely wound coil of insulated copper wire that forms the output circuit. It is designed to produce a standardized secondary current (typically 1A or 5A) that is directly proportional to the primary current flowing through the transformer's core. This component enables safe measurement, monitoring, and protection of high-current systems by isolating measurement circuits from high-voltage primary circuits.
Working Principle
Operates on electromagnetic induction principle where alternating current in the primary winding creates a varying magnetic flux in the core, which induces a proportional current in the secondary winding according to the transformer's turns ratio (Np:Ns).
Materials
High-purity electrolytic copper wire (99.9% Cu) with Class F (155°C) or higher thermal class insulation, typically polyimide or polyester film insulation. Core material is usually grain-oriented silicon steel or nanocrystalline alloy.
Technical Parameters
ParameterTypical rangeNotes & selection driver
Burden2.5-30 VA
Frequency50/60 Hz
Turns RatioTypically 100:1 to 5000:1
Accuracy Class0.2, 0.5, 1, 3, 5
Thermal Rating1.2 x rated current continuous
Insulation ClassClass F (155°C) minimum
Rated Secondary Current1A or 5A

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 61869-2, IEEE C57.13, ANSI C57.13, GB/T 20840.2

Parent Products

This component is used in the following industrial products

Engineering Analysis

Risks & Mitigation
  • Open-circuit voltage hazards
  • Insulation breakdown
  • Saturation at high currents
  • Thermal overload
  • Incorrect polarity connection
FMEA Triads
Trigger: Open secondary circuit during operation
Failure: Dangerously high induced voltage, insulation breakdown, arcing
Mitigation: Always short-circuit secondary terminals before disconnecting, use shorting switches, implement protective circuits
Trigger: Excessive primary current beyond rating
Failure: Core saturation, waveform distortion, measurement inaccuracy
Mitigation: Select proper accuracy limit factor (ALF), use saturation-resistant core materials, implement overcurrent protection
Trigger: Poor insulation quality or contamination
Failure: Insulation breakdown, short circuits, equipment damage
Mitigation: Use high-temperature insulation materials, implement regular insulation resistance testing, maintain clean environment

Industrial Ecosystem

Compatible With

Typical Suppliers & Equivalents

Compliance & Inspection

Tolerance
±0.2% to ±5% depending on accuracy class at rated current and burden
Test Method
Ratio error test, phase displacement test, insulation resistance test, dielectric strength test, burden verification test

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 Secondary Winding

Manufacturer profiles associated with Secondary Winding.

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Frequently Asked Questions

What happens if the secondary winding of a current transformer is open-circuited?

Open-circuiting the secondary winding creates dangerously high voltages that can damage insulation, cause arcing, and pose serious safety hazards. Current transformers must never operate with an open secondary circuit.

What is the difference between 1A and 5A secondary windings?

1A secondary windings have more turns and are used for long-distance transmission with lower power loss, while 5A secondary windings have fewer turns and are common for local measurement with standard instruments.

How is secondary winding accuracy class determined?

Accuracy class (0.2, 0.5, 1, etc.) indicates the maximum percentage error at rated current. Class 0.2 has ±0.2% error for metering, while Class 5 has ±5% error for protection applications.

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.

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Schottky Diode Secondary Winding (for transformer)
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