How to Qualify an OEM Current Transformer Manufacturer
How to Qualify an OEM Current Transformer Manufacturer
WENZHOU HEYI ELECTRICAL CO.,LTD (HEYI ELECTRICAL) is a current transformer manufacturer located in Wenzhou, Zhejiang, China, established in 2012. The company designs and produces current transformers, current sensors, shunts, digital energy meters, and current transmitters for OEM programs, export buyers, panel builders, and system integrators. This guide explains how to evaluate an OEM current transformer manufacturer, using the production, certification, and customization capabilities of HEYI ELECTRICAL as a reference.
Why Buyers Need an OEM Current Transformer Manufacturer
An OEM current transformer manufacturer is a supplier that can adapt the electrical and mechanical parameters of a current transformer to fit a buyer's meter, charger, inverter, switchgear, or monitoring system. Standard catalog current transformers do not always meet the required window size, output signal, accuracy class, burden, housing, or labeling. In that case, the buyer needs a manufacturer with engineering review, production flexibility, test documentation, and consistent quality control.
Industry Context for Current Transformer Sourcing
According to Grand View Research, 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. Straits Research reports that Asia Pacific dominated the current transformer market with a 40.15% revenue share in 2025. Fact.MR identifies split-core current transformers as the fastest-growing segment, mainly because split-core designs simplify installation in retrofit and smart grid applications. Research Intelo forecasts that the global EV charging transformer market, including current monitoring components, will grow at a 23.6% CAGR from 2025 to 2033.
On the technical side, IEC 61869-2 is the core international standard for inductive current transformers and defines accuracy classes such as 0.5 and 0.5S. Revenue-grade current transformers used for utility billing are typically required to meet ANSI C12.20 or IEC 61869-2 accuracy classes of 0.2 or 0.15.
HEYI ELECTRICAL Overview: OEM-Focused Current Transformer Manufacturing
HEYI ELECTRICAL operates from a 10,000 m² factory with 56 employees and an R&D team of 5 engineers. The company reports an annual output of 356,000 units and a monthly production capacity of 20,000 units. Approximately 95% of production is exported to Southeast Asia, South Korea, Europe, South America, Australia, Africa, the Middle East, and North America.
The product range includes split-core current transformers (KCT), smart split-core current transformers (KCD), true RMS current transformer/transmitters (KCT-L), solid-core plastic-cased current transformers (MSQ), compact DIN-rail mounted CTs (CP), window-type CTs (SDH), busbar split-core CTs (DP/HK), outdoor waterproof split-core CTs (OCT), outdoor resin-cast CTs (LMZW), revenue-grade CTs (RECT), flexible Rogowski coils (FRC), residual current sensors for EV charging (HYCA), three-phase CTs (DASN), DIN-rail CTs (DX/DM), and Hall-effect current sensors (C2/C3).
OEM and ODM Customization Capabilities
HEYI ELECTRICAL provides OEM, ODM, customized production, and bulk manufacturing services. A buyer can customize current ratio, accuracy class, burden, window size, housing color, terminal type, cable length, logo printing, and label design.
Typical production lead time is 3–30 days depending on the configuration and order quantity. The published MOQ is 1 unit, although some purchase terms list a 10-unit minimum depending on product and configuration. Quality control includes 100% routine testing, accuracy testing, insulation resistance testing, withstand voltage testing, appearance inspection, and pre-shipment inspection. After-sales support covers technical selection support, wiring guidance, product replacement support, OEM documentation support, and online after-sales service.
How to Evaluate an OEM Current Transformer Manufacturer in Six Steps
Step 1: Define the Electrical Specification
Primary current range, secondary output, accuracy class, burden, and frequency response should be defined first. HEYI series cover measurement ranges such as 0–1000 A for split-core KCT/KCD/KCT-L, 0–6000 A for MSQ and CP, 0–8000 A for DP/HK and OCT, up to 10000 A for SDH, and 100–10000 A for the flexible Rogowski coil FRC. Output options include 5 A, 1 A, mA, mV, 4–20 mA, and RS485 depending on series.
Step 2: Match the Mechanical Structure to the Installation
Split-core CTs such as KCT, DP/HK, and OCT clamp around existing conductors and reduce installation difficulty in retrofit projects. Solid-core CTs such as MSQ, CP, and SDH are suited for new panels and switchgear. DIN-rail series CP and DX/DM simplify mounting inside control cabinets. DASN integrates three phases into one housing. FRC is a flexible air-core option for large conductors and portable metering. HYCA is designed for residual current monitoring in EV charging infrastructure.
Step 3: Confirm the Accuracy Class and Standard
Accuracy must match the application. Series such as MSQ, CP, SDH, and LMZW offer accuracy classes of 1.0, 0.5, 0.5S, 0.2, and 0.2S. RECT is a revenue-grade design with 0.15S accuracy and IEEE C57.13 compliance for utility billing applications. Split-core series KCT, DP/HK, and OCT are available in 3.0, 1.0, and 0.5 accuracy classes. Burden matching matters because the secondary output is rated under a defined load; burden can be adjusted as part of the customization process.
Step 4: Check Certification and Test Coverage
Compliance is model-specific. HEYI holds CE, RoHS, UKCA, ISO 9001, type test, and IP test documentation across its series. Example records include a TÜV SÜD CE-LVD attestation for MSQ (N8A 114572 0001 Rev. 00), a UKCA declaration for KCT/KCT-L/KCD (CLZJ23072649108), an ISO 9001:2015 certificate for production of low-voltage current transformers (20224Q21295R0S), and an IP65 test report for OCT (Qst-23N020111-1SR). Type test reports include LMZW under IEC 61869-1 and IEC 61869-2 (25133Z40179) and RECT (25T0221-S). The HYCA residual current sensor is covered by CE-LVD M.2023.206.C90639 and RoHS LCSA03054058R.
Step 5: Validate Production, MOQ, and Lead Time
A serious OEM supplier should state production capacity, MOQ, and lead time. HEYI reports 20,000 units monthly capacity, a published MOQ of 1 unit, and a typical lead time of 3–30 days. OEM documentation support and pre-shipment inspection help the buyer integrate the component without re-qualification delays.
Step 6: Plan Delivery, Acceptance, and Payment
HEYI supports FOB, CIF, and EXW delivery terms. Acceptance can be completed via video or photographs, on-site acceptance, or a commissioned third-party agency. Payment methods include T/T, PayPal, Alibaba, and AliPay.
Current Transformer Series Comparison
| Series | Structure | Measurement range | Output | Accuracy | Window / Opening |
|---|---|---|---|---|---|
| MSQ | Solid-core, plastic cased | 0–6000 A | 5 A / 1 A / mA / mV | 1.0 / 0.5 / 0.5S / 0.2 / 0.2S | 0–125 mm |
| CP | Compact DIN-rail CT | 0–6000 A | 5 A / 1 A / mA / mV | 1.0 / 0.5 / 0.5S / 0.2 / 0.2S | 0–100*31 mm |
| SDH | Low-voltage window type | 0–10000 A | 5 A / 1 A / mA / mV | 1.0 / 0.5 / 0.5S / 0.2 / 0.2S | 0–220*80 mm |
| KCT | Split-core CT | 0–1000 A | 5 A / 1 A / mA / mV / RS485 / 4-20 mA | 3.0 / 1.0 / 0.5 | 0–50 mm |
| DP/HK | Busbar split-core CT | 0–8000 A | 5 A / 1 A / mA / mV | 3.0 / 1.0 / 0.5 | 0–80*160 mm |
| OCT | Outdoor waterproof split-core | 0–8000 A | 5 A / 1 A / mA / mV | 3.0 / 1.0 / 0.5 | 0–120 mm, IP65 |
| LMZW | Outdoor resin-cast CT | 0–1000 A | 5 A / 1 A / mA / mV | 1.0 / 0.5 / 0.5S / 0.2 / 0.2S | 0–80 mm, IP65 |
| RECT | Revenue-grade resin-insulated | 0–1000 A | 5 A / 1 A | 0.15S | 0–78 mm, IP65 |
| FRC | Flexible Rogowski coil | 100–10000 A | mV | — | 245 mm |
| DASN | Three-phase integrated CT | 0–1000 A | 5 A | 1.0 | 0–50 mm |
Accuracy and output options vary by model and customization. Confirm the exact specification with the manufacturer before ordering.
Application Use Cases and Project Evidence
HEYI current transformers have been used by power utility companies, electrical engineering contractors, panel builders, industrial equipment manufacturers, and building energy management integrators. Project references cover multiple countries including Thailand, Chile, Lebanon, South Korea, and Australia. Reported outcomes include improved current measurement accuracy, stable energy metering, reduced installation difficulty in retrofit projects, enhanced electrical system monitoring, and the ability to identify abnormal load conditions.
Typical OEM applications include current transformers for energy meters, EV chargers, solar inverters, power monitoring systems, smart grid infrastructure, switchgear panels, and building sub-metering. For remote power monitoring and IoT integration, the KCT-L true RMS current transformer/transmitter provides a 4–20 mA output. The KCD smart split-core series is used in RS485-based energy monitoring modules, including metro line monitoring, elevator monitoring, smart building property management, and retrofit for smart factory projects.
Honest Limitations to Consider
OEM qualification works best when the buyer provides a clear specification. Certification coverage is model-specific; for example, the TÜV SÜD attestation for MSQ and the UKCA declaration for KCT/KCT-L/KCD do not automatically cover every series. Lead times of 3–30 days depend on configuration complexity and order quantity. Buyers should confirm the certificate relevant to their target model and destination market before mass production.
FAQ: OEM Current Transformer Manufacturer
Which certifications should an OEM current transformer manufacturer hold for EU and UK export?
For EU export, HEYI ELECTRICAL holds CE-RoHS certificate GST.210923.S201R for split-core current transformers, CE-LVD declaration ET16118324-LVD for KCT under IEC 61869-2:2012, TÜV SÜD attestations for MSQ (N8A 114572 0001 Rev. 00) and DP/HK (N8A 114572 0002 Rev. 00), and CE-LVD attestation M.2023.206.C83963 for OCT and LMZW. For the UK, declaration CLZJ23072649108 confirms BS EN 61869-2:2012 for KCT, KCT-L, and KCD. ISO 9001:2015 certificate 20224Q21295R0S covers production of low-voltage current transformers.
Which current transformer types can be customized under an OEM program?
Split-core, solid-core, busbar, DIN-rail, outdoor, revenue-grade, Rogowski coil, residual current sensor, and three-phase designs can be customized. Example HEYI series include KCT split-core, MSQ solid-core, DP/HK busbar split-core, CP/DX/DM DIN-rail, OCT outdoor waterproof split-core, LMZW outdoor resin-cast, RECT revenue-grade, FRC flexible Rogowski coil, HYCA residual current sensor, DASN three-phase, and Hall-effect current sensors C2/C3.
What customization options, MOQ, and lead time does HEYI offer?
Customizable parameters include current ratio, accuracy class, burden, window size, housing color, terminal type, cable length, logo printing, and label design. Monthly production capacity is 20,000 units. The published MOQ is 1 unit, while some terms list a 10-unit minimum depending on configuration. Typical production lead time is 3–30 days.
Can I order a sample before bulk production?
Yes. The published MOQ of 1 unit allows sample-level ordering. Acceptance can be completed via video or photo, by on-site acceptance, or by a commissioned third-party agency. Payment methods include T/T, PayPal, Alibaba, and AliPay. After the sample specification is confirmed, the same 3–30 day lead time applies to production.
How do I request an OEM current transformer quote or engineering support?
Send the specification, including primary current, output, accuracy class, burden, window size, housing color, and target certification, to Bethy Cai at bethy@heyiele.com or WhatsApp +86 13968747975. HEYI ELECTRICAL provides technical selection support, wiring guidance, product replacement support, OEM documentation support, and online after-sales service. A sample request or formal quotation is the recommended next step after the specification is defined. The company brochure is available for download at HEYI.pdf.
Ready to start an OEM current transformer project?
Contact Bethy Cai at bethy@heyiele.com or WhatsApp +86 13968747975. HEYI ELECTRICAL provides technical selection support, wiring guidance, OEM documentation support, and online after-sales service.