Dielectric heating method for moisture extraction from an active part of a transformer

Dielectric heating with high-frequency electric fields addresses the inefficiencies of conventional methods by directly generating heat within transformer dielectric material, ensuring thorough and efficient moisture extraction with targeted heating.

EP4593041A1Active Publication Date: 2025-07-30HITACHI ENERGY LTD
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Patent Information

Application Number
EP2024153935
Authority / Receiving Office
EP · EP
Patent Type
Applications
Current Assignee / Owner
Filing Date
2024-01-25
Publication Date
2025-07-30
Estimated Expiration
2044-01-25

AI Technical Summary

Technical Problem

Conventional heating methods for moisture extraction in transformers, such as using kerosene vapor and hot air, are time-intensive and energy-consuming, particularly challenging for drying thick blocks of pressboard material, and it's difficult to ensure uniform drying across the material.

Method used

A dielectric heating method using high-frequency alternating electric fields at radio frequencies to generate heat directly within the moist regions of the transformer's dielectric material, utilizing internal and external electrodes to target specific areas for moisture extraction.

Benefits of technology

The method achieves faster and more energy-efficient moisture extraction with a reverse temperature gradient, preventing overheating and ensuring thorough drying by generating more heat where moisture is present, thus reducing time and energy consumption.

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Abstract

A dielectric heating method for moisture extraction from an active part (10) of a transformer (1) is provided. The method comprises a step of configuring a system including at least one an apparatus (2) configured to generate electric fields alternating at radio frequencies, wherein the electric fields penetrate at least part of regions between freely selectable electrodes (3). The method further comprises a step of operating the at least one apparatus (2) for drying at least one moist region (7) of the active part (10) of the transformer (1), wherein the at least one moist region (7) is located at least partially between the freely selectable electrodes (3), so that the at least one moist region (7) is exposed to the generated alternating electric fields, resulting in heat generation within the at least one moist region (7).
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Citation Information

Patent Citations

  • Method for producing transformers, especially transformers for distribution systems, and a device for carrying out this method

    US5424513A

  • Drying device for a core equipped with electrical windings, preferably of a transformer

    DE2155524A1

  • Method for reducing the moisture of an insulation-coated winding and a spraying device for reducing moisture

    US20120124855A1

Cited By

  • Dielectric heating method for moisture extraction from an active part of a transformer

    WO2025157441A1