IEEE C57.12.20-1997
Standard for Overhead Type Distribution Transformers, 500 kVA and Smaller: High Voltage 34500 Volts and Below: Low Voltage, 7970/13800Y Volts and Below
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About This Item
C57.12.20-1997 is a technical standard for overhead type distribution transformers rated 500 kVA and smaller, with high voltage at 34500 volts and below and low voltage at 7970/13800Y volts and below. It defines a focused framework for design and rating expectations in power distribution equipment, helping align transformer construction with common utility and industrial requirements. For engineers, buyers, and compliance teams, this standard supports clearer specification and evaluation of transformer performance and insulation requirements.
About C57.12.20-1997
This standard addresses overhead distribution transformers used in electrical power systems where compact, pole-mounted or overhead installation is typical. C57.12.20-1997 is relevant to the technical details that affect transformer selection, including voltage class, kVA rating, and the characteristics expected for service in distribution networks. As a superseded document, it remains useful for understanding legacy design requirements, procurement references, and comparisons with later transformer specifications in the same family of engineering practice.
Where is C57.12.20-1997 used?
C57.12.20-1997 is most closely associated with overhead distribution transformer applications in utility feeders, rural and suburban distribution lines, and similar power delivery environments. It may also be used in industrial or institutional power systems that rely on medium-voltage distribution equipment and step-down service. The technical context includes electrical equipment selection, insulation coordination, and transformer ratings for systems operating within the stated high-voltage and low-voltage limits.
Importance in practice
In practice, C57.12.20-1997 helps reduce uncertainty in transformer specification, testing, and procurement by setting a common reference for equipment within its rating range. It supports consistency across design, manufacturing, and acceptance checks, which can lower the risk of mismatched voltage classes or unsuitable transformer ratings. For organizations managing legacy equipment or comparing historical requirements, the standard can be an important guide for compliance review and engineering continuity.
- Overhead distribution transformer ratings
- High-voltage and low-voltage limits
- Utility and feeder applications
- Legacy specification reference
- Design and procurement consistency
- Publication Date: 2002
- Standard Status: Superseded
- Publisher: IEEE
- Subject: Power, Energy and Industry Applications; Components, Circuits, Devices and Systems; Engineered Materials, Dielectrics and Plasmas
- Official IEEE: Doi link
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