IEEE C57.92-1981

Name: IEEE C57.92-1981
Brand: IEEE

Withdrawn

IEEE Guide for Loading Mineral-Oil-Immersed Power Transformers Up to and Including 100 MVA with 55 C or 65 C Average Winding Rise

Withdrawn date

10-17-2023

Published date

12-14-1981

Publisher

Institute of Electrical & Electronics Engineers

1. Scope
2. References
3. General
3.1 Limitations
3.2 Transformer Life Expectancy
3.3 Transformer Rated Output
3.4 Aging of Insulation
3.5 Ambient Temperature and Its Influence on Loading
3.6 Operation With Part or All of the Cooling Out of
      Service
3.7 Supplemental Cooling of Existing Self-Cooled
      Transformers
4. Transformers Specified to Have an Average Winding
      Rise of Not More Than 65 deg C and Hottest-Spot
      Winding Rise of Not More Than 80 deg C
4.1 Basic Loading for Normal Life Expectancy
4.2 Short-Time Loading with Moderate Sacrifice of Life
      Expectancy
5. Transformers Specified to Have an Average Winding
      Rise of Not More Than 55 deg C and Hottest-Spot
      Winding Rise of Not More Than 65 deg C
5.1 Basic Loading for Normal Life Expectancy
5.2 Short-time Loading with Moderate Sacrifice of Life
      Expectancy
6. Calculation of Temperature and Loss of Life for
      Short-Time Loads Above Transformer Rating
6.1 General
6.2 Top-Oil Rise Determination
6.3 Hottest-Spot Conductor to Top-Oil Gradient
6.4 Hottest-Spot Conductor Temperature
6.5 Percent Loss of Life
6. Method of Converting Actual to Equivalent Load Cycle
6.7 Equations for Calculating Transient Heating of Oil-
      Immersed Transformers
7. Method Used for Computer Calculation of Loading
      Capability Tables
7.1 Method
FIGURES
1. Life Expectancy Curve
2. Approximate Continuous Loading for Normal Life
      Expectancy-65 deg C Rise Transformers
3. Maximum Loss of Life - 65 deg Rise Transformers
4. Approximate Continuous Loading for Normal Life
      Expectancy-55 deg C Rise Transformers
5. Maximum Percent Loss of Life - 55 deg C Rise Trans-
      formers
6.(a) and (b) Initial Oil Rise
7.(a) and (b) Top-Oil Temperature at End of Specified
              Load Period
8.(a) and (b) Ultimate Oil Rise
9.(a) and (b) Hottest-Spot Conductor To Top-Oil Gradient
10. Assumed Load Cycle
11. Actual Load Cycle
NUMEROUS TABLES
APPENDIX
Unusual Temperature and Altitude Conditions

Describes loading mineral-oil-immersed power transformers, manufactured in accordance with ANSI C57.12.10-1976 (1) and ANSI C57.12.30-1977 (2) and others up to and including 100 MVA maximum nameplate rating. Based mostly on ageing of winding insulation.

Committee	Transformers
DocumentType	Standard
PublisherName	Institute of Electrical & Electronics Engineers
Status	Withdrawn

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