Chapter A General rules of electrical installation design

More documents

Recommendations

Info

N52 © Schneider Electric - all rights reserved N - Characteristics of particular sources and loads 5 Asynchronous motors The importance of limiting the voltage drop at the motor terminals during start-up In order to have a motor starting and accelerating to its normal speed in the appropriate time, the torque of the motor must exceed the load torque by at least 70%. However, the starting current is much higher than the full-load current of the motor. As a result, if the voltage drop is very high, the motor torque will be excessively reduced (motor torque is proportional to U 2 ) and it will result, for extreme case, in failure to start. Example: b With 400 V maintained at the terminals of a motor, its torque would be 2.1 times that of the load torque b For a voltage drop of 10% during start-up, the motor torque would be 2.1 x 0.9 2 = 1.7 times the load torque, and the motor would accelerate to its rated speed normally b For a voltage drop of 15% during start-up, the motor torque would be 2.1 x 0.85 2 = 1.5 times the load torque, so that the motor starting time would be longer than normal In general, a maximum allowable voltage drop of 10% is recommended during start-up of the motor. 5.4 Maximum rating of motors installed for consumers supplied at LV The disturbances caused on LV distribution networks during the start-up of large direct-on-line AC motors can cause considerable nuisance to neighbouring consumers, so that most power-supply utilities have strict rules intended to limit such disturbances to tolerable levels. The amount of disturbance created by a given motor depends on the “strength” of the network, i.e. on the short-circuit fault level at the point concerned. The higher the fault level, the “stronger” the system and the lower the disturbance (principally voltage drop) experienced by neibouring consumers. For distribution networks in many countries, typical values of maximum allowable starting currents and corresponding maximum power ratings for direct-on-line motors are shown in Figures N71 and N72 below. Type of motor Location Maximum starting current (A) Overhead-line network Underground-cable network Single phase Dwellings 45 45 Others 100 200 Three phase Dwellings 60 60 Others 125 250 Fig. N71 : Maximum permitted values of starting current for direct-on-line LV motors (230/400 V) Location Type of motor Single phase 230 V Three phase 400 V (kW) Direct-on-line starting Other methods at full load (kW) of starting (kW) Dwellings 1.4 5.5 11 Others Overhead 3 11 22 line network Underground 5.5 22 45 cable network Fig. N72 : Maximum permitted power ratings for LV direct-on-line starting motors Since, even in areas supplied by one power utility only, “weak” areas of the network exist as well as “strong” areas, it is always advisable to secure the agreement of the power supplier before acquiring the motors for a new project. Other (but generally more costly) alternative starting arrangements exist, which reduce the large starting currents of direct-on-line motors to acceptable levels; for example, star-delta starters, slip-ring motor, “soft start” electronic devices, etc. 5.5 Reactive-energy compensation (power-factor correction) The method to correct the power factor is indicated in chapter L. Schneider Electric - Electrical installation guide 2008
2 3 Chapter P Residential and other special locations Contents Residential and similar premises P 1.1 General P1 1.2 Distribution boards components P1 1.3 Protection of people P4 1.4 Circuits P6 1.5 Protection against overvoltages and lightning P7 Bathrooms and showers P8 2.1 Classification of zones P8 2.2 Equipotential bonding P11 2.3 Requirements prescribed for each zone P11 Recommendations applicable to special installations P 2 and locations Schneider Electric - Electrical installation guide 2008 P © 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 12 and 13:
Page 14 and 15:
Page 16 and 17:
Page 18 and 19:
A10 © Schneider Electric - all rig
Page 20 and 21:
Page 22 and 23:
Page 24 and 25:
Page 26 and 27:
Page 28 and 29:
Page 30 and 31:
Page 32 and 33:
Page 34 and 35:
Page 36 and 37:
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 44 and 45:
Page 46 and 47:
Page 48 and 49:
Page 50 and 51:
Page 52 and 53:
Page 54 and 55:
Page 56 and 57:
Page 58 and 59:
Page 60 and 61:
Page 62 and 63:
Page 64 and 65:
Page 66 and 67:
Page 68 and 69:
Page 70 and 71:
Page 72 and 73:
Page 74 and 75:
Page 76 and 77:
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 91 and 92:
Page 93 and 94:
Page 95 and 96:
Page 97 and 98:
Page 99 and 100:
Page 101 and 102:
Page 103 and 104:
Page 105 and 106:
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:
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: L22 © Schneider Electric - all rig
Page 346 and 347: © Schneider Electric - all rights
Page 354 and 355: M10 © Schneider Electric - all rig
Page 366 and 367: N28 © Schneider Electric - all rig
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 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?