IEEE 1538:2000 pdf download.IEEE Guide for Determination of Maximum Winding Temperature Rise in Liquid-Filled Transformers.
This guide provides guidance for developing mathematical models and test programs to determine the steady state maximum (hottest-spot) and average winding temperature rise over ambient for all liquid-immersed distribution, power, network, and regulating transformers manufactured in accordance with
IEEE Std C57.12.00-2000.1
1.2 Purpose
IEEE Std C57.12.O0-2000, subclause 5.11.1.1, states. “the maximum (hottest-spot) winding temperature rise above ambient temperature shall be determined by either
a) Direct measurement during a thermal test in accordance with IEEE Std C57.l 2.90-1999. A sufficient number of direct reading sensors should be used at expected locations of the maximum temperature rise as indicated by prior testing or loss and heat transfer calculations.
b) Direct measurement on an exact duplicate transformer design per a).
c) Calculations of the temperatures throughout each active winding and all leads. The calculation method shall be based on fundamental loss and heat transfer principles and substantiated by tests on production or prototype transformers or windings.”
This guide describes recommendations for a manufacturer’s test program or mathematical model to demonstrate compliance with the above requirements.
2. References
This guide should be used in conjunction with the following publications. When the following publications are superseded by an approved revision, the revision should apply.
IEEE Std C57.12.OO-2000, IEEE Standard General Requirements for Liquid-Immersed Distribution, Power, and Regulating Transformers.2
IEEE Sid C57.12.80-1978 (Reaff 1992), IEEE Standard Terminology for Power and Distribution Transformers.
IEEE Std C57.12.90-1999, IEEE Standard Test Code for Liquid-Immersed Distribution, Power, and Regulating Transformers and IEEE Guide for Short-Circuit Testing of Distribution and Power Transformers.
3. Definitions
3.1 average winding temperature rise: The arithmetic difference between the average winding temperature and the ambient temperature as determined from the change in the ohmic resistance measured across the terminals of the winding in accordance with the test procedures specified in IEEE Std C57.12.90-1999.
3.2 bottom-oil temperature: The temperature of the liquid as measured at an elevation below the bottom of the coils or in the oil flowing from the liquid cooling equipment.
3.3 bottom-oil temperature rise: The arithmetic difference between the bottom-oil temperature and the ambient air temperature.
3.4 core form transformer: A transformer in which those parts of the magnetic circuit surrounded by the windings have the form of legs with two common yokes.
3.5 directed flow: Indicates that the principal part of the pumped oil from heat exchangers or radiators is forced to flow through the windings.
3.6 distribution transformer: A transformer for transferring electrical energy from a primary distribution circuit to a secondary distribution circuit or consumer’s service circuit.
3.7 flow direction: A pattern of flow in disc or helical windings caused by alternately blocking the vertical ducts inside and outside the winding to cause the liquid to flow in a zigzag pattern. This construction is used with either directed or non-directed flow transformers.
3.8 H-factor: A dimensionless number for predicting the maximum winding temperature rise over fluid due to increased eddy losses and other factors at the winding hottest-spot location.
3.9 hot-spot: A nonrecommended abbreviated term frequently used as a synonym for the maximum or hottest-spot temperature rise of a winding.IEEE 1538 pdf download.