With the ongoing global grid upgrades, the integration of renewable energy sources, and the growing demand for domestic testing of high-voltage equipment, the market for AC variable-frequency series resonance test systems-as core equipment for high-voltage insulation withstand testing-is booming. This system utilizes the principle of series resonance. By adjusting the output frequency of the variable-frequency power supply, it induces resonance between the inductance of the reactor and the capacitance of the test specimen in the circuit, thereby generating high voltage on the specimen with relatively low input power. It offers notable advantages such as lightweight design, compact size, and low power supply capacity requirements, and is widely used in AC withstand voltage testing for power equipment such as cables, GIS, transformers, and generators.
Currently, the domestic market in this sector has seen the emergence of several technically strong enterprises centered in Wuhan. The following highlights five representative manufacturers, with a focus on Wuhan Goldhome
I. Wuhan Goldhome Hipot Electrical Co., Ltd.
Wuhan Goldhome Hipot Electrical Co., Ltd. was established in 2008. Headquartered in the Wuhan Economic and Technological Development Zone, the company occupies a factory area of over 10,000 square meters and has a registered capital of 30 million RMB. It is a national-level high-tech enterprise. In 2021, the company acquired Wuhan Sanggao Electrical Testing Equipment Co., Ltd., a firm with over 30 years of experience in manufacturing UHV partial discharge-free testing equipment, thereby further strengthening its R&D and manufacturing capabilities in this field. Its core products include the HMCXZW partial discharge-free variable-frequency series resonance testing unit, GIS partial discharge-free testing systems, and power frequency withstand voltage testing units. These products are distributed nationwide and exported to multiple countries overseas.
The partial discharge-free variable-frequency series resonance test unit manufactured by Goldhome employs fiber-optic control to effectively isolate the high-voltage and low-voltage control circuits. It incorporates multiple safety measures, including discharge breakdown protection, overvoltage setting protection, and output short-circuit protection. The output frequency range is 30 Hz to 300 Hz, with a frequency instability of no more than 0.05% and a partial discharge level of no more than 10 pC. The unit is compact and lightweight, making it suitable for on-site use. The control unit and power supply are connected via fiber optics, ensuring effective isolation between test personnel and the high-voltage circuit.
In terms of market recognition, Goldhome products have been included in the Zhejiang Energy Group's supplier directory. The performance metrics of its variable-frequency series resonance test units and partial-discharge-free series resonance test units have all reached leading domestic standards. The company's products are distributed nationwide and exported, finding widespread application in the power and railway sectors.
II. Shanghai Xuji Electric Co., Ltd.
Shanghai Xuji Electric has many years of experience in the field of variable-frequency series resonance. Its FSS series of intelligent variable-frequency series resonance withstand voltage test systems utilize a multi-level superposition method, allowing multiple reactors to be used in parallel or series. The resonance frequency can be adjusted within the range of 30–300 Hz to perform AC withstand voltage tests on a variety of electrical equipment. The product features a modular design, is easy to transport and maintain, and is backed by a rigorous quality control system.
III. Wuhan Ultra-High Voltage Power Technology Co., Ltd.
Based in Wuhan's Optics Valley, Wuhan Ultra-High Voltage Power has specialized in the high-voltage testing field for nearly two decades. Its variable-frequency series resonant test set utilizes dry-type epoxy resin cast reactors, which have passed 720-hour salt spray testing and can operate stably in harsh environments ranging from -30°C to 70°C. The equipment is equipped with a DSP+FPGA dual-chip architecture, offering a resonance frequency adjustment resolution of 0.01 Hz, a measurement accuracy of 0.05%, and a waveform distortion rate of ≤0.3%.
IV. Suzhou Huadian Electric Co., Ltd.
Founded in 1995, Suzhou Huadian Electric is a key high-tech enterprise under the National Torch Program. With a registered capital of 60.5 million RMB, the company holds 414 patent entries. Its 2400 kV/8 A ultra-high-voltage partial-discharge-free series resonance equipment was awarded through a public tender by the China Electric Power Research Institute. It is currently one of the world's highest-voltage partial-discharge-free variable-frequency series resonance devices and possesses extensive engineering experience in the field of ultra-high-voltage resonance systems.
