IEEE C57.12.23-2002 pdf download IEEE Standard for Underground Type, Self-Cooled, Single-Phase, Distribution Transformers with Separable Insulated High-Voltage Connectors; High Voltage 25 000 V and Below; Low Voltage 600 V and Below; 167 kVA and Smaller
1.Overview
1.1 Scope
This standard covers certain electrical, dimensional, and mechanical characteristics and takes intoconsideration certain safety features of single-phase, 60 Hz, mineral-oil-mmersed, self-cooled, distributiontransformers with separable insulated high-voltage connectors. These transformers are rated 167 kVA andsmaller, with high voltages of 25 000 V and below and with low voltages of 600 V and below. Thesetransformers are generally used for step-down purposes from an underground primary cable supply and aresuitable for occasional submerged operation.
This standard does not cover the electrical and mechanical requiremments of any accessory devices that maybe supplied with the transformer.
1.2 Purpose
This standard is intended for use as a basis for determining performance, interchangeability, and safety ofthe equipment covered, and to assist in the proper selection of such equipment.
2.References
This standard shall be used in conjunction with the following publications. When these publications aresuperseded by an approved revision, the revision shall apply:
ANSI C57.12.20-1997, American National Standard for Overhead-Type Distribution Transformers,500kVA and Smaller: High voltage, 34 500 Volts and Below; Low Voltage, 7970/13 800 Y Volts and Below.
3. Ratings
3.1 Kilovoltampere ratings
Kilovoltampere ratings shall be continuous and based on, but not exceeding, an average winding temperaturerise of 55 “C and a hottest-spot temperature rise of 70 C. The temperature rise of the insulating oil shall bemeasured near the top of the tank and shall not exceed 55 C. The transformers shall have a temperature-riseinsulation system of 65 C
Kilovoltampere ratings shall be as follows: 25,37.5,50,75,100,167
The kilovoltampere ratings for transformers conforming to this standard shall be suitable for continuousoperation at the rated kilovoltamperes, provided that the temperature of the cooling air (enclosure ambienttemperature) does not exceed 50 C and the average temperature of the cooling air does not exceed 40 “C forany 24-hour period.
IEEE C57.12.23-2002 pdf download
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