IEEE 1538-2000 pdf download IEEE Guide for Determination of Maximum Winding Temperature Rise in Liquid-Filled Transformers
3. Definitions
3.1 average winding temperature rise: The arithmetic difference between the average winding temperatureand the ambient temperature as determined from the change in the ohmic resistance measured across the ter-minals 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 ofthe 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 theambient air temperature.
3.4 core form transformer: A transformer in which those parts of the magnetic circuit surrounded by thewindings 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 isforced to flow through the windings.
3.6 distribution transformer: A transformer for transferring electrical energy from a primary distributioncircuit 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 verticalducts inside and outside the winding to cause the liquid to flow in a zigzag pattern. This construction is usedwith either directed or non-directed flow transformers.
3.8 H-factor: A dimensionless number for predicting the maximum winding temperature rise over fluid dueto 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 hot-test-spot temperature rise of a winding.
3.10 maximum (hottest-spot) winding temperature: The maximum or hottest temperature of the currentcarrying components of a transformer winding and leads in contact with insulation or insulating fluid. Thehottest-spot temperature is a naturally occurring phenomena due to the generation of losses and theheat-transfer phenomena. It is the highest temperature inside the transformer winding and leads and is greater than the measured average winding temperature, All transformers have a maximum (hottest-spot)winding temperature.
NOTE–In this guide the hottest-spot rise is not considered to be due to localized manufacturing defects. Defectsthat affect long term performance or cause the hottest-spot rise to exceed the limits set in IEEE StdC57.12.00-2000 should be corrected.
3.11 maximum (hottest-spot) winding temperature rise: The arithmetic difference between maximum(hottest-spot) winding temperature and the ambient temperature.
3.12 network transformer: A transformer designed for use in a vault to feed a variable capacity system ofinterconnected secondaries. A network transformer may be of the submersible or of the vault type
3.13 nondirected flow: Indicates that the pumped fuid from the heat exchangers or radiators flows freelyinside the tank,and is not forced to flow through the windings.
3,14 oil: A shortened term for mineral oil that is a specially refined mineral-oil for use as an insulating liquicand coolant in transformers. For the purposes of this document, when terms such as “top oil rise” are used.”oilshould be considered synonymous with “fuid”since fuids other than mineral oil are used. SeeIEEE Std C57.12.00-2000.
3.15 power transformer: A transformer that transfers electric energy in any part of the circuit between thegenerator and the distribution primary circuits.
3.16 prototype transformer: A transformer manufactured primarily to obtain engineering data or evaluatemanufacturing or design feasibility. Prototypes may be preproduction units or units typical of currentdesigns manufactured for test purposes to obtain data to comply with changes in industry standards or forother reasons.
IEEE 1538-2000 pdf download
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