On August 26, 2025, the group standard “Electrical Properties and Evaluation Methods of Metallized Film for DC Capacitors in Flexible DC Transmission Systems” (Project No. CESBZ2024018), led by Wuxi Sun.King Power Capacitor Co., Ltd. in collaboration with Tsinghua University, Xi’an High Voltage Apparatus Research Institute Co., Ltd., and 10 other leading enterprises in film-drawing and coating, successfully passed the final review organized by the China Electrotechnical Society.

This achievement marks a milestone in the standardization of core materials for DC capacitors in flexible DC transmission systems in China. It also highlights Sun.King Technology Group’s leading expertise in core technology development and standard-setting in the power equipment sector.

Filling the Industry Gap and Supporting Green Energy Development

In flexible DC transmission systems, DC capacitors are key to ensuring stable system operation. Metallized film, as the core dielectric material of DC capacitors, directly determines their safety and reliability. For a long time, there has been no dedicated standard, either domestically or internationally, for the electrical properties and evaluation methods of metallized films used in flexible DC capacitors. Existing standards only cover general physical, chemical, and electrical performance requirements of insulating films, which do not meet the higher demands of flexible DC capacitors, nor do they provide a systematic evaluation of the critical factors affecting metallized film performance.

The main challenge of this project lay in defining the electrical properties and evaluation methods for metallized films while extending requirements to the base films and resins. This was also the key point of debate among the expert reviewers.

To address this challenge, Sun.King took the initiative to unite universities and leading enterprises in film-drawing and coating to launch the standardization work. The standard applies to the evaluation of polypropylene metallized films for DC capacitors in flexible DC transmission systems, filling an industry gap and providing unified, scientific technical guidelines for quality control of key materials. It will strongly support performance improvements in critical equipment for green energy and promote high-quality industrial development.

Focusing on Core Properties and Building a Scientific Evaluation System

During the drafting process, the working group developed a comprehensive and rigorous evaluation system focusing on the core electrical properties of metallized films. The standard also provides clear definitions, normative references, and detailed test procedures, ensuring both operability and comparability of results. This delivers a complete “from indicators to methods” technical solution for the industry.

Setting an Industry Benchmark and Demonstrating Sun.King’s Commitment

This is the first standard issued by the Capacitor Standards Working Group of the China Electrotechnical Society, making it a landmark achievement. Passing the review reflects the joint efforts of the project team and demonstrates Sun.King’s strong technical capabilities and industry influence in the field of metallized films for flexible DC capacitors.

As the leading unit, Sun.King adheres to the philosophy of “Pursuing Excellence, Creating Win-Win Futures.” The Group not only advances technology innovation and product upgrading in flexible DC transmission and power capacitors but also actively participates in the formulation of industry standards, contributing to the sustainable and standardized development of the sector.

Looking Ahead

Sun.King will continue to leverage its technological and resource advantages to promote the dissemination and implementation of this standard, helping industry players enhance product quality. Guided by standardization, the Group will further increase R&D investment, drive breakthroughs in core technologies, and contribute more “Sun.King Strength” to the localization of flexible DC capacitors, the secure and stable operation of flexible DC transmission systems, and the sustainable development of green energy.