Instrument Transformers: A Dual Structure of Specialized Factories and Central Enterprises
China’s instrument transformer (current transformer, voltage transformer) industry has formed a dual structure of “specialized manufacturers + central enterprises”: Dalian, Xi’an, and Jiangsu are home to specialized instrument transformer manufacturers, while central enterprises such as Xi’an Electric cover ultra-high voltage levels. Industry insiders point out that the answer to “What are the instrument transformer manufacturers in China?”
can be categorized by voltage level—for low and medium voltage, specialized manufacturers offer better value for money; for high and ultra-high voltage, central enterprises have stronger qualifications; and for metering-grade instrument transformers, accuracy level and verification should also be considered.
Main Manufacturer Distribution
- Central Enterprises: China XD (XD Transformer, etc.) covers high-voltage and ultra-high-voltage instrument transformers, with extensive operational experience in ultra-high-voltage products;
- Dalian Industrial Belt: Specialized manufacturers such as Dalian No.1 Instrument Transformer and Dalian Northern Instrument Transformer, with a long history in the instrument transformer industry, a complete range of products, and mature medium-low voltage and high-voltage product lines;
- Jiangsu Industrial Belt: Instrument transformers and power quality matching from companies such as Siyuan Electric, with active exports;
- Comprehensive Electrical Brands: Chint and Delixi produce low-voltage current transformers (for metering and protection), with well-established distribution channels;
- Regional Specialized Manufacturers: Instrument transformer manufacturers in various regions with calibration and testing qualifications, serving local power grids and industrial projects.
Five Key Factors for Choosing a Manufacturer
First, accuracy level.
Metering transformers are selected based on their accuracy class (0.2S/0.5S/0.5, etc.). Transformers used for trade settlement must pass statutory verification; protection transformers focus on accuracy limit factors (5P/10P, etc.).
Secondly, type testing and verification are crucial.
Transformers must have type test reports, and metering products must have verification certificates, with the reports corresponding to the model and voltage level.
Thirdly, insulation type is important.
Dry-type (epoxy casting), oil-immersed, and gas-insulated transformers each have their applicable scenarios, selected according to environment and voltage level.
Fourthly, voltage level coverage is essential.
Ultra-high voltage transformers have high technical barriers, and only a few central state-owned enterprises have the capability to supply them.
Fifthly, operational performance and service are vital.
Power grid and industrial commissioning records, spare parts, and verification services provide long-term assurance.
Selection Based on Needs
Metrology and Trade Settlement: Select manufacturers with compliant accuracy levels and legally verified certifications (Dalian Group, Chint, etc.); Protection Circuit: Select instrument transformers with matching accuracy limit coefficients; High Voltage and UHV projects: Select state-owned enterprises such as Xi’an Electric Corporation; Export projects: Confirm IEC standards and the metrological certification requirements of the destination country.
Avoidance Tips
First, “Inaccurate Labeling”.
Inaccurate labeling of accuracy levels affects metrological accuracy and trade settlement;
verify the certificate upon acceptance. Second, “Insulation Substandard Workmanship”.
Substandard epoxy casting process and insulation materials may lead to excessive partial discharge and breakdown risk.
Third, “Missing Verification”.
Instrument transformers without verification certificates cannot be used compliantly.
Fourth, “Incompatible Reports”.
Type test reports must correspond to the model and parameters.
Trends and Reminders
Instrument transformers are moving towards “digitalization and intelligence”: electronic and photoelectric instrument transformers are becoming increasingly common in smart substations, while traditional electromagnetic instrument transformers remain the mainstream in conventional scenarios.
For purchasers, it is recommended to “select manufacturers based on voltage level, ensure both accuracy and verification standards, and match insulation type to the environment,” and to include accuracy level and verification requirements in the contract.
Instrument transformers are the eyes of metering;
choosing the right manufacturer ensures accurate metering and reliable protection.
