5200_O02 - .631.<21.116 41.m.g Power[‘(CLV\3 QY mch ~...

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Unformatted text preview: .631.» <21 .116 41%.. ..m.g Power [‘(CLV\3+QY mch ~ “9.4. X X eh X7. gCL‘H'V'Isst 7:3?){CaA "\0 SCC/‘ (8/241/50 MVA 55-? 20.5/270/3325’ m/A éSQ OA ' 664$, poo\C/c¥ OA/FA/FA FA — {am « Coolsé wwy M/flg/POA Yové§oy3Vz>Y52 o)! moVes flA/k/Wl/FOW b3 C G Y\V€CJY'1‘OV\ (VCG~JS> FéA , OH ‘6 IQUVW(Ja$, (QWC/wbérED “IL/’1 ")th (“a Aficikra 0W A a‘x w is blown JyVYOwSx (QAKASWW: {6W , oil Poem/)ecl “Um/oust he “V exokw c: v , 0&0:ch wo‘eé . ’0, {619/ (Q) TéLQ) (96¢ 5i??? OA/flA/(KA / ' $€HT"C,OO[§;& 7§°C) Q ’ 9B4] 9 Gm: “rams 550C) ? ’ s‘Faycbe \ + S'QCV‘)‘ 2 "KM: OA "/pA/FJA /~ S€W'Caa{ci 76/1” 2 ' (51,—Oxlf One Godlike) '* «Yam 8g°Clg ’ ##ozc< VLMSO CGGZINB—vgw; *(wqu 14‘ alarm Hs+ 5 0+ 'J‘Mmgwwk . . _ A 7' 7W7) Ya’hnas -WVEAMS; Icy; Ox/ 76:1/70 ‘ W ” MAX Amp/ML 40°C 40°C \\ 7;, m 0,. °ro ‘ 55"1172 {27ch 761/73 ,3)”: 6' L $5 C, / \ H0 'NMW WW ,,.,W W ”“ch Q’g C -- w~~~~~ m ’ *Ei:j*=rl A [O 5 oCL -\_. " N893 Designat‘l'n‘ons" 5.1 Cooling classes of transformers Transformers shall be identified according to the cooling method employed. For liquid-immersed transformers, this identification is expressed by a four-letter code as described below. These designations are consistent with EC 60076-2: 1993. First letter: Internal cooling medium in contact with the windings: O mineral oil or synthetic insulating liquid with fire point7 S 300 'C K insulating liquid with fire point > 300 °C L insulating liquid with no measurable fire point Second letter: Circulation mechanism for internal cooling medium: N natural convection flow through cooling equipment and in windings F forced circulation through cooling equipment (i.e., coolant pumps), natural convection flow in windings (also called nondirected flow) D forced circulation through cooling equipment, directed from the cooling equipment into at least the main windings Third letter: External cooling medium: A air W water Fourth letter: Circulation mechanism for external cooling medium: N natural convection F forced circulation [fans (air cooling), pumps (water cooling)] NOTES: l—ln a transformer with forced, nondirected cooling, (second code letter F), the rates of coolant flow through all the windings vary with the loading, and are not directly controlled by the pumps. The pumped oil flows freely inside the tank and is not forced to flow through the windings. 2-—-In a transformer designated as having forced directed coolant circulation (second code letter D), the rate of coolant flow through the main windings is determined by the pumps and not by the loading. A minor fraction of the coolant flow through the cooling equipment may be directed outside the main windings to provide cooling for core and other parts. Regulating windings and/or other windings having relatively low power may also have nondirected coolant circulation. A transformer may be specified with more than one power rating (also referred to as cooling stages). The transformer nameplate shall list the rated power and cooling class designation for each rating. The ratings shall be listed in order of increasing power. The cooling class designations are normally listed in order with a diagonal slash separating each one. Examples: ONAN/ONAF. The transformer has a set of fans which may be put in service as desired at high load- ing. The coolant circulation is by natural convection only. ONAN/OFAF. The coolant circulation is by natural convection only at base loading. However. the transformer has cooling equipment with pumps and fans to increase the power-carrying capacity at high loading. Examples of the cooling class designations used in IEEE Std C57. 12.00-1993 and in previous revisions, and the corresponding new designations, are provided in Table 2. 7Fire point—The lowest temperature at which a specimen will sustain burning for 5 s. (ASTM D92-l998. ”Cleveland Open Cup" test method.) 8 ‘ ' annwinhro annn IFFF All rinhts reserved. IEEE LlQUlD-IMMERSED DISTRIBUTION, POWER, AND REGULATING TRANSFORMERS Std 057.12.00-2000 Table 2—Cooling class designation Present designations Previous designations ONAN/ONAF/ONAF OA/FA/FA ONAN/ONAF/OFAF OA/FA/FOA ONAN/ODAF OA/FOA“ ONAN/ODAF/ODAF OA/FOAa/FOA£l ODAF FOAa “Indicates directed oil flow per Table 9, NOTE 2 of IEEE Std C57.12.00-1993. 5.2 Frequency Unless otherwise specified, transformers shall be designed for operation-at a frequency of 60 Hz. 5.3 Phases 5.3.1 General Transformers described in this standard are either single-phase or three—phase. Standard ratings are included in the product standards for particular types of transformers. When specified, other phase arrangements may be provided. 5.3.2 Scott-connected or T-connected transformers 5.3.2.1 Phase transformation These may be provided to accomplish three-phase to two-phase transformation, or vice versa; or to accom— plish three-phase to three—phase transformation. Several arrangements commonly utilized to accomplish such transformations are described here. 5.3.2.2 Dissimilar single-phase transformers Two single-phase transformers are assembled in an enclosure, and permanently interconnected, with the fol- lowing characteristics: a) Performance characteristics shall be based on bank operation of three—phase to two—phase transfor- mation or vice versa. b) The single—phase transformers may not be identical or interchangeable. Copyright © 2000 lEEE. All rights reserved. 9 ...
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