Daqo Secures TÜV Rheinland CTF Stage 2 Authorization and IECEE CB Certificates for Multiple Transformer Models

Zhenjiang Daqo Power Transformer Co., Ltd., an oil-immersed transformer manufacturer under Daqo Group, has received TÜV Rheinland Customer Testing Facility (CTF) Stage 2 authorization. In addition, several transformer models developed for energy storage applications have obtained IECEE CB Test Certificates.

Together, the two milestones support different stages of international project delivery. The CTF Stage 2 authorization enables eligible tests to be conducted at Zhenjiang Daqo's own laboratory under the witness supervision of TÜV Rheinland engineers. With applicable CE certificates already in place for relevant European-market models, the newly obtained IECEE CB Test Certificates provide internationally recognized test evidence for key transformer performance and safety-related requirements, supporting subsequent market-specific certification.

Bringing Certification Testing Closer to Manufacturing

The authorization followed TÜV Rheinland's assessment of the laboratory's quality management system, technical personnel, test equipment, calibration controls and environmental conditions.

Under the CTF Stage 2 framework, eligible tests can now be conducted at Zhenjiang Daqo's facility under the witness supervision of TÜV Rheinland engineers. This reduces the need to transport large transformer units to external laboratories and limits the time required for external scheduling and cross-party coordination.

Based on Daqo's experience with comparable projects, testing and certification through an external laboratory typically takes six to eight weeks. Under the CTF Stage 2 model, the process is expected to be reduced to approximately three to four weeks.

For customers, this can help:

• shorter certification lead times;

• improve technical coordination and schedule predictability across tendering, approval and delivery;

• reduce transportation risks and coordination costs for large transformer units;

• and support more efficient testing of new ratings, frequencies and project-specific configurations.

The model is already being applied in practice. An SL3500/33-0.69 transformer has completed relevant testing at the facility for a European renewable energy project.

IECEE CB Test Certificates for Energy Storage Transformer Models

The transformer models covered by the latest IECEE CB Test Certificates include:

• SFL-8800/33/0.66kV-0.66kV

• SFL-9000/33/0.8kV-0.8kV

• SFL-6600/33/0.8kV-0.8kV

• SFL-4400/33/0.8kV

The portfolio is designed primarily for renewable energy and energy storage applications and covers both 50 Hz and 60 Hz grid environments.

TÜV Rheinland tested and evaluated the products in accordance with the IEC 60076 series of standards. The resulting CB certificates provide independently verified test evidence that can support further certification in target countries and regions, reducing the need for repeated testing and helping customers move more efficiently through market-specific approval processes.

For customers, the certificates provide independent evidence that the products have been tested against international standards. They also support clearer product selection and a more efficient technical response when projects involve different grid requirements.

According to TÜV Rheinland, Zhenjiang Daqo Power Transformer is among the first transformer manufacturers in China to receive the CTF Stage 2 authorization. The two companies plan to continue their technical and certification cooperation, including work on additional distribution transformer products.

Victor Gu, General Manager of Zhenjiang Daqo Power Transformer, said:“For international projects, testing and certification are not simply final approval steps; they have a direct impact on project schedules. Bringing eligible testing closer to our engineering and manufacturing operations allows us to consider certification requirements earlier, confirm project-specific designs more quickly and reduce uncertainty later in the delivery process. This strengthens Daqo's ability to provide customers with a quicker technical response and more predictable project execution.”