Overseas Project Selection Guide: 110 kV Oil-Immersed Transformer IEC, IEEE, and GB Standards Analysis

Time：2025-11-26    Auther：ZTelec-www.ztelectransformer.com

Selecting the correct 110 kV oil-immersed transformer is a critical step in overseas power project development. Different countries and regions may strictly require IEC, IEEE, or GB standards. If the selected transformer fails to comply, it can lead to equipment incompatibility, delays, increased costs, and even project failure. This guide compares key differences among the three major international transformer standard systems and provides technical advice for procurement teams.

110 kV Oil-Immersed Transformer Basic Overview

The 110 kV oil-immersed transformer is a medium-high voltage device widely used in industrial distribution networks, commercial power systems, and transmission lines. Key parameters include rated capacity (e.g., 10 MVA, 25 MVA), 110 kV high-voltage side rating, three-phase structure, and cooling methods such as ONAN/ONAF for oil-immersed and AN/AF for dry-type transformers. Understanding these parameters is the foundation for overseas transformer selection.

Overview of IEC, IEEE, and GB Transformer Standard Systems

IEC (International Electrotechnical Commission)

IEC standards are widely adopted globally (except most of North America) and emphasize safety, universality, and interchangeability. Many countries use IEC as the foundation for their transformer regulations.

IEEE (Institute of Electrical and Electronics Engineers)

IEEE standards dominate the United States, Canada, and parts of Latin America. They emphasize operational performance, field experience, and detailed testing requirements, making them one of the strictest transformer standards.

GB (Chinese National Standards)

GB standards are applied within China and increasingly in overseas projects cooperating with Chinese EPC contractors. Based initially on Soviet standards, GB has evolved to integrate IEC concepts and match Chinese power grid conditions.

Comparative Characteristics of the Three Standard Systems

IEC standards prioritize global universality and adaptation to diverse environmental conditions. IEEE standards emphasize system compatibility, mechanical strength, and long-term operational safety. GB standards include local material requirements and additional tests for challenging environments such as high humidity or pollution-heavy regions.

Key Technical Differences Among IEC, IEEE, and GB Standards

1. Design Requirements

• **Insulation Class**: IEC uses BIL values based on rated voltage; IEEE focuses on impulse design; GB combines IEC concepts with local adaptations.
• **Temperature Rise**: IEC and IEEE clearly limit winding and oil temperature rise; GB may prioritize durability under local grid conditions.
• **Short-Circuit Strength**: IEEE has stricter requirements for mechanical reinforcement.

2. Testing Standards

• **IEC Tests**: Temperature rise, lightning impulse, short circuit, partial discharge.
• **IEEE Tests**: More emphasis on load cycling, voltage fluctuation, and humid/hot environmental adaptability.
• **GB Tests**: Based on IEC but include extra tests for high humidity and high pollution regions.

Overseas Project Selection Recommendations

1. Confirm Mandatory Local Standards

Countries like Saudi Arabia adopt IEC + local SASO requirements, while the U.S. requires full IEEE compliance. Ensuring the oil-immersed transformer meets local regulations is essential.

2. Consider Maintenance and Interchangeability

Transformers built to IEC or IEEE standards allow easier spare parts sourcing and maintenance support across international markets.

3. Verify Insulation Levels and Bushing Compatibility

Insulation requirements differ across standards and must match the local environment (thunderstorm frequency, contamination levels). Supporting equipment such as bushings and surge arresters must match the insulation level of the oil-immersed transformer.

4. Check Technical Specifications Carefully

Large overseas project tenders often mix multiple standards. Each technical clause must be reviewed to avoid contradictions and ensure compliance during the bidding stage.

5. Choose Manufacturers with Multi-Standard Design Capability

Manufacturers capable of producing IEC-, IEEE-, and GB-compliant oil-immersed transformers can provide better technical support, customization, and global project adaptability.

The 110 kV oil-immersed transformer is vital equipment in international power construction. By comparing the IEC, IEEE, and GB standard systems and considering load requirements, environmental conditions, and special technical clauses, purchasers can make informed and accurate decisions. Selecting the appropriate standard ensures project reliability, safety, and long-term operational performance—even under diverse overseas conditions.