Recommended Current Transformer Manufacturers: Selection Guide

Evaluating current transformer manufacturers is a structured procurement decision that affects metering accuracy, compliance, and long-term reliability. This guide outlines the key selection criteria and profiles one qualified supplier—WENZHOU HEYI ELECTRICAL CO.,LTD (HEYI)—using verifiable production, certification, and product data. HEYI is a Chinese manufacturer of current transformers and current sensors based in Wenzhou, Zhejiang, founded in 2012.

The Challenge: Choosing a Current Transformer Manufacturer

Buyers sourcing current transformers for energy meters, EV chargers, solar inverters, or power monitoring systems face the same evaluation problem: how to verify that a manufacturer can deliver consistent accuracy, compliance, and supply stability. Without standardized technical data and traceable certifications, procurement decisions often rely on unverified claims. The following sections provide a data-based path to shortlist manufacturers that meet international standards and OEM requirements.

Current Transformer Market Context

The global current transformer market was estimated at USD 2.63 billion in 2024 and is projected to reach USD 3.90 billion by 2030, according to Grand View Research. The Asia Pacific region holds the largest share, with 40.15% of revenue in 2025 (Straits Research). Among product types, split-core current transformers are the fastest-growing segment due to ease of installation in retrofits and smart grid applications (Fact.MR). Buyers should also note that international standard IEC 61869-2 is the core reference for inductive current transformer accuracy classes, replacing IEC 60044-1.

Industry concentration remains moderate: the top five global players—ABB, Siemens, GE, Schneider Electric, and Arteche—held approximately 40% of the market in 2024 (Global Market Insights). This leaves significant room for specialized manufacturers like HEYI, which focuses on low-voltage current transformers and sensors for global distribution.

HEYI ELECTRICAL: Company Capability and Product Range

HEYI ELECTRICAL, operating from a 10,000 m² factory with 56 employees and an annual output of 356,000 units, specializes in current transformers, current sensors, shunts, digital energy meters, and current transmitters. The company exports 95% of its production to Southeast Asia, South Korea, Europe, South America, Australia, Africa, the Middle East, and North America. An in-house R&D team of 5 engineers supports customized OEM and ODM development.

Current transformer assembly line at HEYI factory

Main Product Families

HEYI's catalog covers the most requested current transformer types for industrial and commercial energy management:

Split-core current transformers (models KCT, KCD) — for retrofits without busbar disconnection, with measurement up to 1000 A and options for 4–20 mA, RS485, or mV outputs.
Solid-core / window-type current transformers (models MSQ, CP, SDH, DX/DM) — for new installations and switchgear, covering ranges up to 10,000 A and accuracy classes down to 0.2S.
Busbar split-core CTs (model DP/HK) — large window up to 80×160 mm, suitable for busbar monitoring in industrial plants.
Revenue-grade CTs (model RECT) — designed for utility billing, with 0.15S accuracy and epoxy resin insulation.
Outdoor waterproof CTs (models OCT, LMZW) — IP65-rated housing with UV protection for overhead and utility monitoring.
Flexible Rogowski coils (model FRC) — lightweight, non-saturating sensors for currents up to 10,000 A.
Three-phase CTs (model DASN) — compact 3-in-1 units for DIN-rail or panel integration.
Hall Effect current sensors (model C2/C3) — DC-current capable transducers for PV, battery storage, and industrial automation.

Specification Table: HEYI Product Series

Model	Type	Measurement Range	Output	Accuracy	Key Application
KCT	Split-core CT	0–1000 A	5A / 1A / mA / mV / RS485 / 4-20mA	3.0 / 1.0 / 0.5	EV charging, smart grid, energy monitoring
MSQ	Solid-core / square window	0–6000 A	5A / 1A / mA / mV	1.0 / 0.5 / 0.5S / 0.2 / 0.2S	Switchgear, HVAC, data centers
DP/HK	Busbar split-core	0–8000 A	5A / 1A / mA / mV	3.0 / 1.0 / 0.5	Industrial energy monitoring, busbar retrofit
OCT	Outdoor waterproof split-core	0–8000 A	5A / 1A / mA / mV	3.0 / 1.0 / 0.5	Overhead line monitoring, solar, railway trackside
RECT	Revenue-grade resin-insulated	0–1000 A	5A / 1A	0.15S	Utility billing, substation metering
FRC	Flexible Rogowski coil	100–10000 A	mV	—	Heavy industry, portable testing, transient currents
DASN	3-phase integrated	0–1000 A	5A	1.0	IDC, telecom, UPS, motor control centers

Step-by-Step Evaluation Criteria for a Current Transformer Manufacturer

Verify compliance documentation. Request certificates such as ISO 9001:2015, CE-LVD, CE-EMC, UKCA, and RoHS. Check the certificate numbers and issue/expiry dates. HEYI holds ISO 9001:2015 (cert. 20224Q21295R0S), CE-LVD (e.g., M.2023.206.C83963), CE-EMC (B-E2505D2378), UKCA (CLZJ23072649108), and multiple RoHS certificates (e.g., GST.210923.S201R).
Assess product breadth and customization. A flexible manufacturer should offer current ratio, accuracy class, burden, window size, housing color, terminal type, cable length, logo printing, and label design as customization options. HEYI supports these specifications across its product lines.
Evaluate production and quality control. Look for data on factory size, staff, monthly capacity, and test procedures. HEYI lists a monthly capacity of 20,000 units and a quality control system that includes 100% routine testing, accuracy tests, insulation resistance tests, withstand voltage tests, appearance inspection, and pre-shipment inspection.
Check long-term reliability and customer base. Long-running projects and applications with utilities, contractors, and panel builders indicate stability. HEYI reports a 10-year project history serving power utilities, electrical engineering contractors, panel builders, industrial equipment manufacturers, and building energy management integrators across countries including Thailand, Chile, Lebanon, South Korea, Australia, and others.
Confirm lead time, MOQ, and aftersales support. A reasonable MOQ for evaluation is essential. HEYI's lead time is 3–30 days with an MOQ of 1 unit, supported by after-sales services including technical selection support, wiring guidance, product replacement support, OEM documentation support, and online after-sales service.

HEYI factory inspection and customization capabilities

Use Cases and Application Scenarios

Current transformers from HEYI are used in current measurement, energy metering, load monitoring, feeder monitoring, switchgear retrofit, relay protection, generator output monitoring, and building sub-metering, according to company case data. The product range supports several high-growth application areas:

EV charging infrastructure: The HYCA residual current sensor is built for AC/DC leakage detection, with a switching output for 6 mA DC and 30 mA AC per IEC 62752, making it suitable for mode 2 and mode 3 charging.
Smart grid and switchgear: Split-core and solid-core models are widely used in panel retrofit and feeder monitoring, with accuracy classes up to 0.2S for revenue applications.
Solar and energy storage: Hall Effect sensors and split-core CTs are applied to PV string monitoring and BMS battery storage.
Data centers and telecom: Three-phase models like DASN integrate into IDC rack-level monitoring and remote power panels.

Outdoor waterproof split-core current transformer installed for utility monitoring

Certification and Quality Assurance: What to Verify

Documentation is a primary trust signal in current transformer procurement. Below are representative certificates held by HEYI, mapped to market requirements:

CE-LVD (2014/35/EU) — Certificate M.2023.206.C83963 covers outdoor models OCT and LMZW, tested to IEC 60044-1:2003 and IEC 61869-2:2012.
CE-EMC (2014/30/EU) — Certificate B-E2505D2378 covers the DP/HK busbar split-core CT, tested to EN IEC 61000-6-3:2021 and EN IEC 61000-6-1:2019.
UKCA — Certificate CLZJ23072649108 for KCT, KCT-L, and KCD models, compliant with BS EN 61869-2:2012.
RoHS — Certificates for split-core CTs and fluxgate residual current sensors, including SGS verification (SHAEC2123838801).
Type test reports — Including LMZW outdoor CT tested to IEC 61869-1/-2 by Zhejiang Fangyuan Test Group, and RECT revenue CT tested by Suzhou Electrical Apparatus Science Research Institute.

TUV SUD Attestation of Conformity for HEYI current transformer

Frequently Asked Questions

1. What certifications should a current transformer manufacturer have?

A qualified manufacturer should hold at least ISO 9001 for quality management, CE-LVD and CE-EMC for the European market, UKCA for the UK, and RoHS for material compliance. HEYI ELECTRICAL holds ISO 9001:2015 (cert. 20224Q21295R0S), CE-LVD (e.g., M.2023.206.C83963), CE-EMC (B-E2505D2378), UKCA (CLZJ23072649108), and RoHS certificates for split-core and other products. Buyers should ask for certificate numbers and verify scope and validity.

2. What are the key capabilities of a reliable current transformer manufacturer?

Key capabilities include a wide product range, stable accuracy, reliable insulation performance, and the ability to offer multiple mechanical structures (split-core, window-type, busbar, DIN-rail). Customization of ratio, accuracy, burden, window size, housing color, terminal type, cable length, and logo printing is also a core differentiator. HEYI supports OEM/ODM production with a monthly capacity of 20,000 units and an R&D team of 5 engineers.

3. What is the typical MOQ and cost structure for current transformer orders?

HEYI’s minimum order quantity is 1 unit, which is favorable for testing and custom configurations. Production lead times range from 3 to 30 days depending on product type and order volume. Although specific pricing is not published online, buyers can request quotes directly from the manufacturer for their exact specification – this is the recommended approach because CT pricing varies significantly with accuracy class, output type, and custom housing.

4. Can I get a sample before placing a bulk order?

Yes. Because the MOQ is 1 unit, a sample or pilot order is practical for evaluation. HEYI’s factory is export-oriented, and product documentation includes catalogues and certificates that can be reviewed before ordering. For custom specifications, the manufacturer will provide technical selection support and then produce a sample for testing. This process is a common part of OEM supplier qualification in this industry.

5. What is the lead time for OEM current transformer orders?

HEYI’s standard lead time is 3–30 days. This includes the design and production of custom specifications such as ratio, housing color, terminal type, and logo printing. After-sales support includes technical selection support, wiring guidance, product replacement support, and OEM documentation support. If you are evaluating an OEM supplier, it is reasonable to request a sample first and then scale to bulk production. For a specific project, contact HEYI’s export team at bethy@heyiele.com or via WhatsApp to confirm current lead times and receive a custom quote.

Next Step in Supplier Evaluation

To verify HEYI’s capability against your current transformer requirements, download the company brochure or contact the export team directly.

Download HEYI Brochure (PDF)

Email: bethy@heyiele.com | WhatsApp: +86 13968747975

Website: www.heyiele.com

HEYI factory site and production capacity

Conclusion

Selecting a recommended current transformer manufacturer requires more than a name search. It requires verification of certifications, production capacity, customization flexibility, quality control, and long-term field reliability. HEYI ELECTRICAL, with its 10,000 m² factory, export-oriented operations, ISO 9001 quality system, and a track record spanning 10 years with utilities and industrial customers, is a suitable candidate for OEM and project-based procurement.

Use the evaluation criteria in this guide to build a shortlist, request documentation, and order samples. A data-driven vendor selection process reduces risk in projects that depend on accurate current measurement and stable energy metering.

Menu