Chapter A General rules of electrical installation design

More documents

Recommendations

Info

B26 © Schneider Electric - all rights reserved B - Connection to the MV public distribution network Fig. B23 : Dry-type transformer 4 The consumer substation with LV metering Characteristics related to the technology and utilization of the transformer This list is not exhaustive: b Choice of technology The insulating medium is: v Liquid (mineral oil) or v Solid (epoxy resin and air) b For indoor or outdoor installation b Altitude (
B - Connection to the MV public distribution network Fig. B24 : Hermetically-sealed totally-filled tank Fig. B25 : Air-breathing conservator-type tank at atmosphere pressure 4 The consumer substation with LV metering There are two ways in which this pressure limitation is commonly achieved: b Hermetically-sealed totally-filled tank (up to 10 MVA at the present time) Developed by a leading French manufacturer in 1963, this method was adopted by the national utility in 1972, and is now in world-wide service (see Fig. B24). Expansion of the liquid is compensated by the elastic deformation of the oil-cooling passages attached to the tank. The “total-fill” technique has many important advantages over other methods: v Oxydation of the dielectric liquid (with atmospheric oxygen) is entirely precluded v No need for an air-drying device, and so no consequent maintenance (inspection and changing of saturated dessicant) v No need for dielectric-strength test of the liquid for at least 10 years v Simplified protection against internal faults by means of a DGPT device is possible v Simplicity of installation: lighter and lower profile (than tanks with a conservator) and access to the MV and LV terminals is unobstructed v Immediate detection of (even small) oil leaks; water cannot enter the tank b Air-breathing conservator-type tank at atmospheric pressure Expansion of the insulating liquid is taken up by a change in the level of liquid in an expansion (conservator) tank, mounted above the transformer main tank, as shown in Figure B25. The space above the liquid in the conservator may be filled with air which is drawn in when the level of liquid falls, and is partially expelled when the level rises. When the air is drawn in from the surrounding atmosphere it is admitted through an oil seal, before passing through a dessicating device (generally containing silica-gel crystals) before entering the conservator. In some designs of larger transformers the space above the oil is occupied by an impermeable air bag so that the insulation liquid is never in contact with the atmosphere. The air enters and exits from the deformable bag through an oil seal and dessicator, as previously described. A conservator expansion tank is obligatory for transformers rated above 10 MVA (which is presently the upper limit for “total-fill” type transformers). Choice of technology As discussed above, the choice of transformer is between liquid-filled or dry type. For ratings up to 10 MVA, totally-filled units are available as an alternative to conservator-type transformers. A choice depends on a number of considerations, including: b Safety of persons in proximity to the transformer. Local regulations and official recommendations may have to be respected b Economic considerations, taking account of the relative advantages of each technique The regulations affecting the choice are: b Dry-type transformer: v In some countries a dry-type transformer is obligatory in high apartment blocks v Dry-type transformers impose no constraints in other situations b Transformers with liquid insulation: v This type of transformer is generally forbidden in high apartment blocks v For different kinds of insulation liquids, installation restrictions, or minimum protection against fire risk, vary according to the class of insulation used v Some countries in which the use of liquid dielectrics is highly developed, classify the several categories of liquid according to their fire performance. This latter is assessed according to two criteria: the flash-point temperature, and the minimum calorific power. The principal categories are shown in Figure B26 in which a classification code is used for convenience. As an example, French standard defines the conditions for the installation of liquidfilled transformers. No equivalent IEC standard has yet been established. The French standard is aimed at ensuring the safety of persons and property and recommends, notably, the minimum measures to be taken against the risk of fire. Code Dielectric fluid Flash-point Minimum calorific power (°C) (MJ/kg) O1 Mineral oil < 300 - K1 High-density hydrocarbons > 300 48 K2 Esters > 300 34 - 37 K3 Silicones > 300 27 - 28 L3 Insulating halogen liquids - 12 Fig. B26 : Categories of dielectric fluids Schneider Electric - Electrical installation guide 2008 B27 © Schneider Electric - all rights reserved
Page 1:
2008 http://theguide.schneider-elec
Page 4 and 5: Guiding tools for more efficiency i
Page 6 and 7: General rules of electrical install
Page 8 and 9: J K L M N P Q General contents Prot
Page 10 and 11: © Schneider Electric - all rights
Page 18 and 19: A10 © Schneider Electric - all rig
Page 38 and 39: B 0 © Schneider Electric - all rig
Page 40 and 41: B 2 © Schneider Electric - all rig
Page 42 and 43: B14 © Schneider Electric - all rig
Page 78 and 79: C 0 © Schneider Electric - all rig
Page 80 and 81: C 2 © Schneider Electric - all rig
Page 82 and 83: C © Schneider Electric - all right
Page 84 and 85: C16 © Schneider Electric - all rig
Page 87 and 88: 2 3 4 5 6 7 8 Chapter D MV & LV arc
Page 89 and 90: D - MV & LV architecture selection
Page 105 and 106:
D - MV & LV architecture selection
Page 107 and 108:
Page 109 and 110:
Page 111 and 112:
Page 113 and 114:
Page 115 and 116:
Page 117 and 118:
Page 119 and 120:
Page 121 and 122:
2 3 Chapter E LV Distribution Conte
Page 123 and 124:
E - Distribution in low-voltage ins
Page 125 and 126:
Page 127 and 128:
Page 129 and 130:
Page 131 and 132:
Page 133 and 134:
Page 135 and 136:
Page 137 and 138:
Page 139 and 140:
Page 141 and 142:
Page 143 and 144:
Page 145 and 146:
Page 147 and 148:
Page 149:
Page 152 and 153:
© Schneider Electric - all rights
Page 154 and 155:
Page 156 and 157:
Page 158 and 159:
Page 160 and 161:
F10 © Schneider Electric - all rig
Page 162 and 163:
Page 164 and 165:
Page 166 and 167:
F1 © Schneider Electric - all righ
Page 168 and 169:
Page 170 and 171:
Page 172 and 173:
Page 174 and 175:
Page 176 and 177:
Page 178 and 179:
Page 180 and 181:
Page 182 and 183:
Page 184 and 185:
Page 186 and 187:
Page 188 and 189:
Page 190 and 191:
Page 192 and 193:
Page 194 and 195:
Page 196 and 197:
Page 198 and 199:
Page 200 and 201:
Page 202 and 203:
G10 © Schneider Electric - all rig
Page 204 and 205:
Page 206 and 207:
Page 208 and 209:
Page 210 and 211:
Page 212 and 213:
Page 214 and 215:
Page 216 and 217:
Page 218 and 219:
Page 220 and 221:
Page 222 and 223:
Page 224 and 225:
Page 226 and 227:
Page 228 and 229:
Page 230 and 231:
Page 232 and 233:
Page 234 and 235:
Page 236 and 237:
Page 238 and 239:
Page 240 and 241:
Page 243 and 244:
2 3 4 Chapter H LV switchgear: func
Page 245 and 246:
H - LV switchgear: functions & sele
Page 247 and 248:
Page 249 and 250:
Page 251 and 252:
Page 253 and 254:
Page 255 and 256:
Page 257 and 258:
Page 259 and 260:
Page 261 and 262:
Page 263 and 264:
Page 265 and 266:
Page 267 and 268:
Page 269 and 270:
Page 271 and 272:
2 3 4 Chapter J Protection against
Page 273 and 274:
J - Protection against voltage surg
Page 275 and 276:
Page 277 and 278:
Page 279 and 280:
Page 281 and 282:
Page 283 and 284:
Page 285 and 286:
Page 287 and 288:
Page 289 and 290:
Page 291 and 292:
Page 293 and 294:
Page 295:
Page 298 and 299:
Page 300 and 301:
Page 302 and 303:
Page 304 and 305:
Page 306 and 307:
K10 © Schneider Electric - all rig
Page 308 and 309:
Page 310 and 311:
Page 312 and 313:
Page 314 and 315:
Page 316 and 317:
Page 318 and 319:
Page 320 and 321:
Page 322 and 323:
Page 324 and 325:
Page 326 and 327:
Page 328 and 329:
L10 © Schneider Electric - all rig
Page 330 and 331:
Page 332 and 333:
Page 334 and 335:
Page 336 and 337:
Page 338 and 339:
Page 340 and 341:
Page 342 and 343:
Page 344 and 345:
Page 346 and 347:
Page 348 and 349:
Page 350 and 351:
Page 352 and 353:
Page 354 and 355:
M10 © Schneider Electric - all rig
Page 356 and 357:
Page 358 and 359:
Page 360 and 361:
Page 362 and 363:
Page 364 and 365:
Page 366 and 367:
N28 © Schneider Electric - all rig
Page 368 and 369:
Page 370 and 371:
Page 372 and 373:
Page 374 and 375:
Page 376 and 377:
Page 378 and 379:
Page 380 and 381:
Page 382 and 383:
Page 384 and 385:
Page 386 and 387:
Page 388 and 389:
Page 390 and 391:
Page 392 and 393:
Page 394 and 395:
Page 396 and 397:
Page 398 and 399:
Page 400 and 401:
P10 © Schneider Electric - all rig
Page 402 and 403:
P12 © Schneider Electric - all rig
Page 405 and 406:
2 3 4 5 Chapter Q EMC guidelines Co
Page 407 and 408:
Q - EMC guidelines 2 Earthing princ
Page 409 and 410:
Q - EMC guidelines 3 Implementation
Page 411 and 412:
Page 413 and 414:
Page 415 and 416:
Q - EMC guidelines Fig. Q15 : Imple
Page 417 and 418:
Q - EMC guidelines Fig. Q17b : The
Page 419 and 420:
Q - EMC guidelines 4 Coupling mecha
Page 421 and 422:
Q - EMC guidelines Source Metal shi
Page 423 and 424:
Q - EMC guidelines 4 Coupling mecha
Page 425 and 426:
Q - EMC guidelines Power + analogue
Page 427:
Schneider Electric Industries SAS H
show all

Chapter A General rules of electrical installation design

You also want an ePaper? Increase the reach of your titles

Delete template?

Save as template?