IEEE-Std-ANSI-C57.12.24-2000 pdf download American National Standard for Transformers— Underground-Type Three-Phase Distribution Transformers, 2500 kVA and Smaller; High Voltage, 34 500 GrdY/19 920 Volts and Below; Low Voltage, 480 Volts and Below— Requirements
1 Scope
1.1 This standard is intended to set forth characteristics relating to performance, limited electrical and mechanical interchangeability, and safety of the equipment described, and to assist in the proper selection of such equipment.
1.2 This standard describes certain electrical and mechanical characteristics and takes into consideration certain safety features of three phase, 60-Hz, liquid-immersed, self-cooled, undergroundtype distribution transformers rated 2500 kVA and smaller with high voltages of 34 500GrdY/1 9 920 volts and below and with low voltages of 480 volts and below. These transformers are generally used for step- down purposes from an underground primary cable supply and are suitable for occasional submerged operation.
2 References
When an American National Standard referred to in this document is superseded by a revision approved by the American National Standards Institute, Inc., the revision shall not apply. The referenced standard and the specific referenced edition shall be the applicable referenced standard until the new version of the referenced document is incorporated by formal action or appropriate revision of the citing standard.
NSI C57.1 2.70-1 978 (R 1 987), Terminal Markings and Connections for Distribution and Power Transformers
ANSI C84.1 – 1 995, Electrical Power Systems and Equipment – Voltage Ratings (60 Hertz)
ANSI/ASME B1 .1 -1 989, Unified Inch Screw Threads (un and unr thread form)
ANSI/IEEE 1 00-1 996, Dictionary of Electrical and Eectronics Terms
ANSI/IEEE 386-1 995, Separable Insulated Connector Systems for Power Distribution Systems Above 600 V
ANSI/IEEE C57.1 2.00-1 993, General Requirements for Liquid-immersed Distribution, Power, and Regulating Transformers.
ANSI/IEEE C57.1 2.32 -1 994, Submersible Equipment – Enclosure Integrity
ANSI/IEEE C57.1 2.80-1 978 (R 1 992), Terminology for Power and Distribution Transformers
ANSI/IEEE C57.1 2.90-1 993, Test Code for Liquid-immersed Distribution, Power, and Regulating Transformers and Guide for Short-circuit Testing of Distribution and Power Transformers
ANSI/IEEE C57.91 -1 995, Distribution Transformers rated 500 kVA and Less with 55°C or 65°C Average Winding Rse, Guide for Loading Mineral Oil-immersed Overhead and Padmounted Transformers.
3 Ratings
3.1 Kilovolt-ampere ratings
3.1.1 Kilovolt-ampere (kVA) ratings are continuous and are based on not exceeding a 55°C average winding temperature rise and a 70°C hottest-spot temperature rise. The temperature rise of the insulating
IEEE Std ANSI-C57.12.24-2000 pdf download
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