Overview - IEC/IEEE 65700-19-03:2025 (Bushings for DC application)
IEC/IEEE 65700-19-03:2025 is the second edition international standard that defines requirements for bushings for DC application. It covers outdoor and indoor bushings - capacitance-graded or gas‑insulated - used as components of liquid-filled converter transformers, smoothing reactors, and air‑to‑air DC bushings. The standard applies to both line‑commutated converter (LCC) and voltage‑source converter (VSC) technologies and replaces the 2014 edition. It harmonizes service experience and market needs with related IEC and IEEE bushing standards.
The standard explicitly excludes cable terminations (potheads), instrument-transformer bushings, test power-supply bushings, bushings with external gaseous insulation other than atmospheric air, and bushings for industrial, traction or distribution-class transformers.
Key topics and technical requirements
IEC/IEEE 65700-19-03:2025 provides comprehensive technical coverage, including:
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Ratings and insulation levels
- Rated continuous DC voltage, peak voltage and harmonic voltages
- Rated currents and pollution parameters
- Unified specific creepage distance for DC service
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Operating and design considerations
- Electrical and mechanical requirements, altitude corrections, interchangeability
- Factors affecting design, testing and application (including transformer insulating liquids)
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Test regimes
- Classification of tests: type (design), routine and special tests
- Key test types referenced in the standard:
- Dry power‑frequency voltage withstand with partial discharge measurement
- Lightning and switching impulse withstand tests (LI, SIL/SILSI)
- DC applied voltage withstand and polarity reversal tests with partial discharge
- Temperature rise, cantilever mechanical load, tightness and internal pressure tests
- Electromagnetic compatibility (EMC) emission and immunity tests
- Artificial pollution and wetting tests for polluted or wet conditions
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Marking, inspection and documentation
- Nameplate requirements, dimensional verification, visual inspection and routine measurements (tan δ, capacitance)
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Transport, erection, operation and maintenance
- Recommendations for unpacking, mounting, connections, inspection, maintenance and failure reporting
Applications and users
This standard is essential for:
- Transformer and bushing manufacturers designing DC bushings (capacitance‑graded, gas‑insulated)
- HVDC and DC system engineers (LCC and VSC technologies)
- Utilities and transmission system operators specifying procurement, type testing and acceptance criteria
- Test laboratories performing type, routine and special tests
- Asset owners and maintenance teams implementing installation, operation and upkeep practices
Practical use cases include specification writing for converter transformers and smoothing reactors, factory and site testing, and ensuring safe, reliable DC insulation performance under pollution, wetting and switching conditions.
Related standards
- IEC 60137 - Insulated bushings for alternating voltages above 1 000 V (harmonized content)
- IEEE Std C57.19.00™ - General requirements and test procedures for outdoor power apparatus bushings
Keywords: IEC/IEEE 65700-19-03:2025, bushings for DC application, DC bushings, converter transformer bushings, smoothing reactor bushings, VSC, LCC, bushing testing, partial discharge, IEC 60137, IEEE C57.19.00.