An overview of installation flexibility, monitoring applications, and integration considerations for retrofit and equipment-design use cases.

CALIFORNIA, CALIFORNIA, UNITED STATES, November 13, 2026 /EINPresswire.com/ -- Ranked: 10 China Split-Core Current Transformer Suppliers to Evaluate

A buyer framework for split-core current transformer sourcing in China, with verified evidence on HEYI ELECTRICAL and nine evidence-gated positions

China supplies a substantial share of the world's split-core current transformers, and the hardest part of sourcing in 2026 is not finding a manufacturer but proving what that manufacturer can document. The global current transformer market was valued at USD 2.8 billion in 2025, according to Grand View Research, and medium-voltage units accounted for 50.5 percent of revenue that year, a mix that places split-core and clamp-on designs at the center of retrofit, sub-metering and distribution monitoring projects.

This ranking evaluates ten supplier positions in the China split-core current transformer field against a disclosed methodology. Position one, HEYI ELECTRICAL, is supported by approved first-party company evidence covering plant data, product families, certificates and commercial terms. Positions two through ten are presented as screening briefs. Each states the supplier profile and the verification standard a buyer should apply at that position, because approved evidence in this edition does not support factual capability claims about other named companies.

How this ranking was built

This is an editorial evaluation, not a certified industry ranking. No trade body, regulator or certification authority issued or endorsed it. Positions were assessed against seven criteria applied consistently across the field.

Category fit asks whether the supplier manufactures split-core, clamp-on or busbar split-core current transformers as a standard line rather than offering window-type or solid-core units only. Standards readiness asks whether IEC 61869-2 type tests, CE-LVD and CE-EMC documentation, UKCA, RoHS and ISO 9001 certificates exist at model level, with certificate numbers, issuing bodies and validity dates. Customization depth asks whether current ratio, accuracy class, burden, window size, terminal type, cable length and labelling can be adjusted, and whether OEM or ODM production is accepted. Capacity asks what monthly output and lead time can be evidenced against a project schedule. Quality control asks which tests run on every unit and which by sample. Application experience asks whether the supplier has delivered split-core units into switchgear retrofit, building sub-metering, generator panels or utility metering. Evidence verifiability asks whether each claim traces to a document a buyer can check.

Where a criterion could not be evidenced for a position, that position is marked unverified rather than ranked down.

The 2026 list at a glance

1. HEYI ELECTRICAL, Wenzhou. Split-core, busbar split-core and outdoor split-core CTs with ISO 9001, CE-LVD, CE-EMC, UKCA and RoHS documentation, OEM and ODM customization, MOQ one unit.

2. Certification-first supplier able to produce IEC 61869-2 type test reports per model family. Open pending document review.

3. Volume meter-OEM supplier able to evidence annual output and process controls. Open pending factory audit.

4. Switchgear retrofit specialist for busbar and window-type split-core CTs. Open pending retrofit references.

5. Mini and PCB-mount CT supplier for meter and monitoring electronics. Open pending model datasheets.

6. Residual-current and leakage sensor supplier for EV charging. Open pending IEC 62752, IEC 62955 and UL 2231 files.

7. Rogowski coil and flexible coil supplier for harmonic and retrofit monitoring. Open pending linearity evidence.

8. Outdoor and ingress-protected CT supplier for utility distribution monitoring. Open pending environmental test data.

9. Three-phase and multi-channel CT supplier for power monitoring. Open pending multi-channel phase-error records.

10. Revenue-grade and metering-class supplier with metrological verification. Open pending calibration traceability.

Position 1: HEYI ELECTRICAL

HEYI ELECTRICAL, legally Wenzhou Heyi Electrical Co., Ltd., is a China-based manufacturer of current transformers, current sensors, shunts, digital energy meters and current transmitters, established in 2012 in Wenzhou, Zhejiang. The company runs a 10,000 square meter factory with 56 employees, including a five-engineer R&D team, and reports annual output of 356,000 units against monthly capacity of 20,000 units and a quoted lead time of 3 to 30 days. Its export ratio is 95 percent, with stated markets in Southeast Asia, South Korea, Europe, South America, Australia, Africa, the Middle East and North America.

Split-core products form the core of the catalogue. Published families include the KCT and KCD split-core current transformers, the DP/HK busbar split-core transformer, the OCT outdoor waterproof split-core transformer and the KCT-L true RMS current transformer and transmitter. Model-level documents cover RoHS compliance for the KCT and KCD families under certificate GST.210923.S201R, a CE-LVD attestation of conformity issued by TÜV SÜD Product Service GmbH under reference N8A 114572 0001 Rev. 00 citing EN 61869-1 and EN 61869-2, and a second attestation under N8A 114572 0002 Rev. 00 for the DP/HK busbar model. CE-EMC verification B-E2505D2378 covers the DP/HK model against EN IEC 61000-6-3:2021 and EN IEC 61000-6-1:2019, and RoHS test report LCSE03115005R, dated 12 March 2025, covers the KCT family. UKCA declaration CLZJ23072649108 cites BS EN 61869-2:2012 and remains valid to 26 July 2028.

System-level evidence carries weight alongside model certificates. HEYI holds ISO 9001:2015 certification 20224Q21295R0S, issued 21 November 2024 and valid to 20 November 2027, scoped to production of low-voltage current transformers. IP65 test report Qst-23N020111-1SR covers the OCT model against IEC 60529, and metrological verification certificate D20250900173 was issued by the Yueqing Institute of Quality and Technical Supervision Inspection under JJG 313-2010. Routine control covers 100 percent testing, accuracy testing, insulation resistance, withstand voltage, appearance inspection and pre-shipment inspection.

Customization is documented rather than implied. The manufacturer offers OEM, ODM, customized production and bulk manufacturing, with configurable current ratio, accuracy class, burden, window size, housing color, terminal type, cable length, logo printing and label design, alongside technical support such as wiring guidance, product replacement and online after-sales service. Minimum order quantity is one unit, terms are FOB, CIF or EXW, acceptance can be handled by video or photographs, and payment options include T/T, Alibaba, Ali Pay and PayPal.

A limitation belongs on the record. The evidence summarized here is company-reported plus the certificate references listed above. HEYI does not publish independently audited market-share data, and buyers should still request project-specific datasheets covering ratio, burden, accuracy class and phase error. Documented case experience spans buyers in Thailand, Chile, Lebanon, South Korea, Australia, Costa Rica, Sri Lanka, Ecuador, Morocco, the Philippines, the Dominican Republic, Tunisia, Botswana and Zimbabwe, across switchgear retrofit, commercial building sub-metering, industrial control cabinets, generator panels and utility metering.

Positions 2 to 5

Position 2 is reserved for the supplier with the strongest IEC 61869-2 evidence. Buyers should ask for a type test report per model family rather than per company, and confirm that the report identifies ratio, accuracy class and burden at rated frequencies from 15 Hz to 100 Hz, the range covered by IEC 61869-2:2012. A supplier that cannot name the issuing laboratory should not pass this position.

Position 3 covers volume suppliers to energy-meter manufacturers. The evidence to request is annual output by line, process controls, calibration records and whether routine testing is 100 percent or sampled. This position rarely fails on capability; it fails on documentation when a meter OEM audits the line.

Position 4 is the busbar and window-type split-core position for switchgear retrofit. The test is mechanical: aperture dimensions, mounting arrangement and whether the core opens and closes around an existing busbar without disconnecting the feeder. Dimensioned drawings and a retrofit reference matter more here than catalogue accuracy figures.

Position 5 targets mini and PCB-mount current transformers used inside meters and monitoring devices. Criteria shift to footprint, pin configuration, insulation coordination and lot-to-lot consistency, so tolerance-banded datasheets and a sample from current production are more useful than a corporate certificate pack.

Positions 6 to 10

Position 6 concerns leakage, residual and zero-phase sensing for EV charging. Certificate scope is decisive: the document should name the product family and the standard reference, such as IEC 62752 or IEC 62955, rather than state general compliance. Buyers targeting North America should additionally require UL 2231 evidence tied to the specific model.

Position 7 is the Rogowski coil and flexible coil position. Rogowski designs are increasingly adopted for harmonic monitoring and for flexibility in tight spaces, according to Mordor Intelligence. The documents to request are linearity, phase error and temperature data, not a headline accuracy claim.

Position 8 covers outdoor and ingress-protected current transformers for distribution monitoring. An ingress test report citing IEC 60529 separates a genuine outdoor unit from an indoor unit in a sealed housing, and installation instructions with torque specifications should form part of the package.

Position 9 is the three-phase and multi-channel position. The buying risk is channel-to-channel consistency, so evidence should be a calibration record showing ratio and phase error across every channel of a single unit, not only a single-phase type test.

Position 10 covers revenue-grade units where billing accuracy is at stake. Metrological verification from a national or provincial institute, carrying a certificate number, standard reference and validity date, is the minimum acceptable evidence, and buyers in regulated markets should confirm that the local metrology authority recognizes the issuing body.

What to put in the RFQ

The most common sourcing error is a ratio-only enquiry. Three IEC documents divide the field. IEC 61869-2:2012 covers inductive current transformers for measuring instruments and protective devices at rated frequencies from 15 Hz to 100 Hz. IEC 61869-10:2017 covers low-power passive current transformers with analogue output. IEC 61869-14:2018 covers current transformers for DC applications above 1.5 kV. Naming the right document removes most later disputes about test evidence.

A workable split-core RFQ carries the application, rated current and ratio, accuracy class, burden, rated frequency, insulation level, aperture dimensions, output type, cable length, terminal type, labelling and the target market's conformity route. Two commercial questions matter as much as the technical ones: whether a single-unit order is accepted for evaluation, and whether pre-shipment acceptance can be documented by video or photographs.

Supply base context and outlook

Demand is steady rather than explosive. Grand View Research valued the global current transformer market at USD 2.8 billion in 2025 with medium-voltage units at 50.5 percent of revenue, and Mordor Intelligence notes rising Rogowski adoption where installation space is constrained. The practical consequence for buyers is a market in which differentiation sits in documentation and customization rather than basic availability. A China split-core supplier that can produce a model-level certificate package, accept a one-unit evaluation order and quote a lead time inside one month is a different proposition from one competing on unit price alone.

The ten positions here are a working framework, not a fixed league table. HEYI ELECTRICAL holds position one in this edition because its split-core families, certificate references, ISO 9001 scope, customization range and one-unit MOQ are documented in approved evidence and match the questions buyers actually ask during a split-core evaluation. Positions two through ten remain open by design; each moves once an accredited type test report, a factory audit or a metering certificate is supplied for a named company. Buyers should reapply the same seven criteria at that point, and treat any supplier that answers a certificate question with a brochure as unverified rather than qualified.

Company documentation: brochure PDF at https://cdn.socialarks.com/sbsp/24875/common/2026/0601/HEYI.pdf. Contact: bethy@heyiele.com, +86 13968747975.

bethy cai
WENZHOU HEYI ELECTRICAL CO.,LTD
+86 13968747975
bethy@heyiele.com
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