IEEE C57.12.21-2000
Voltage Bushings: High Voltage (34 500 GrdY/19 920 V and Below) and Low Voltage (240/120 V, 167 kVA and Smaller)
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About This Item
C57.12.21-2000 is a technical standard for voltage bushings used in power, energy and industry applications, focusing on high-voltage bushings rated at 34 500 GrdY/19 920 V and below, as well as low-voltage bushings for 240/120 V systems up to 167 kVA. It helps define the requirements needed to support safe, consistent electrical insulation and reliable transformer-related equipment performance in compact distribution applications.
Overview of C57.12.21-2000
This standard addresses the design and rating context for voltage bushings used with distribution-class equipment. In practice, C57.12.21-2000 provides a technical basis for evaluating bushing suitability across specified voltage levels, helping manufacturers, buyers, and engineers align on construction and performance expectations. Its scope is closely tied to transformer and apparatus applications where insulation integrity, electrical clearances, and dependable operation are important for service continuity.
Typical use cases
The document is commonly relevant when specifying bushings for small power transformers, utility distribution equipment, and related apparatus operating in the stated voltage ranges. It may be used during equipment selection, procurement review, or engineering checks for installations that rely on 34 500 GrdY/19 920 V high-voltage connections or 240/120 V low-voltage service. It is especially useful where compact ratings and controlled electrical interfaces are part of the design.
Why it matters
Using C57.12.21-2000 can help reduce risk in bushing selection by supporting more consistent design and testing expectations. For power and energy applications, that consistency matters because bushings are critical interfaces between energized conductors and grounded structures. A clear standard can improve compliance checking, compare product offerings more effectively, and support safer operation by helping ensure suitable insulation, ratings, and performance for the intended service conditions.
- High-voltage bushings up to 34 500 GrdY/19 920 V
- Low-voltage bushings for 240/120 V applications
- Equipment rated 167 kVA and smaller
- Distribution and transformer interface requirements
- Design, rating, and insulation reference point
- Publication Date: 1992
- Standard Status: Inactive
- Publisher: IEEE
- Subject: Power, Energy and Industry Applications
- Official IEEE: Doi link
- This Version: C57.12.21 (1992)
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