I. Main Features
Light weight, small size: As the most prominent feature, by adopting new materials (such as fiberglass epoxy tubes) and optimizing the design, the equipment weight can be reduced to 1/5 to 1/3 of the traditional oil-immersed transformers of the same capacity.
Dry design: Mostly adopts dry insulation structure with epoxy resin pouring, featuring maintenance-free characteristics, no oil leakage risk, and meeting environmental protection and safety requirements.
High-frequency / Variable-frequency technology: A large number of designs integrate “series resonance” or “high-frequency inverter” technologies. By increasing the working frequency to 100Hz-300Hz, the cross-sectional area of the transformer core and the number of coil turns are significantly reduced, fundamentally achieving equipment miniaturization.
High insulation strength materials: Select high-quality insulation materials and adopt advanced insulation structures, ensuring sufficient insulation performance while reducing the equipment size.
Integrated design: Often integrated with control boxes, voltage regulators, and resonant reactors in a portable box to form an “integrated test device”.
II. Main Technical Types
The main technical paths to achieve “ultra-lightweight” are as follows:
Traditional industrial-frequency dry-type test transformers (improved type)
Principle: Maintain the 50Hz industrial-frequency working mode, adopt dry insulation and forced air cooling technology, and optimize the design to reduce the equipment weight.
Advantages: The structure is relatively simple and the cost is lower.
Disadvantages: The degree of lightweighting is limited. When the equipment capacity increases, the weight will still significantly increase.
Series resonance test device (mainstream ultra-light technology path)
Principle: Based on the “inductance (L) – capacitance (C)” series resonance principle, at the resonance point, the voltage on the capacitive test item is Q times the power supply voltage. The test transformer only needs to provide a smaller excitation voltage to complete the test.
Core reason for lightweighting:
The equipment operates in the 30-300Hz high-frequency range, the volume of the iron core and the coil is significantly reduced;
Most of the test voltage is generated by the resonant reactor, the transformer itself bears a lower voltage;
The overall weight is distributed to the transformer, multi-section combined reactors, and voltage dividers, etc., and each component is lightweight.
Advantages: Extremely light weight, high output voltage, good voltage waveform, little damage to the test item, high equipment safety.
Disadvantages: The system structure is relatively complex, the cost is high.
High-frequency high-voltage test power supply
Principle: Use power electronic inverter technology to directly generate thousands of Hz high-frequency alternating current voltage, and realize voltage boosting through high-frequency transformers.
Advantages: The volume can be minimized and the weight is the lightest.
Disadvantages: The technology is complex, the cost is high, the capacity is usually small, and it is mostly suitable for laboratories or specific test scenarios.
III. Selection and Application Considerations
Clarify test requirements: Determine the required high output voltage, large output current (capacity), and test objects (such as cables, GIS, generators, etc.) in advance.
Technical path selection:
For withstand voltage tests of long cables and large capacitance test items, the series resonance device is the recommended solution, and it is also the mainstream technology for “ultra-lightweight” equipment to be applied in on-site tests currently.
For small-capacity, routine insulation withstand voltage tests, dry industrial-frequency test transformers have higher economic efficiency.
Balancing portability and functionality: Although ultra-lightweight equipment may not be as good as large fixed equipment in some extreme performance indicators, it can fully meet the standard requirements of most on-site preventive tests.
Equipment quality control: High-voltage test equipment has extremely high requirements for safety and reliability. Choose mature products and ensure that the equipment has undergone strict verification.
Post time: Jan-07-2026