10080-1-ENGG-GUI-EL-002 Rev1

CABLE SIZING CALCULATION FOR LT FEEDERS - XLPE INSULATED COPPER AND XLPE INSULATED ALUMINIUM CABLES
Table no.1 (Please refer Annexure-1)
SUPPLY VOLTAGE 415 V Power Factor 0.85 Ground Temperature rating factor: (Ft) 1.03 For ground temperature 25⁰C
% MAX VOLTAGE DROP AT FULL LOAD 2% Sinø 0.53 Depth of laying (Fd) 0.97 (Worst case for 300 Sqmm Cable)
Thermal Resistivity (Fth) 0.89 Backfill material thermal resistivity assumed to be 2.0 Km/W
Group Rating factor (Fg) 0.43 Refer Annexure-2A
Other rating factors 1.2 Margin considering 80-90% loading of each cable in a group (heating effect ᾀ load2)
Total Rating Factor 0.459

% VMAX x 10 x VSUPPLY
FORMULA: LMAX PERMISSIBLE =
√3 x I x (R Cosø + X Sinø)

XLPE INSULATED COPPER AND XLPE INSULATED ALUMINIUM AND FLAT WIRE ARMOURED DIRECT BURIED
DATA FOR CABLE TYPE
COPPER ALUMINIUM
CROSS SECTION sqmm 2.5 4 10 16 25 35 50 70 95 120 150 185 240 300 2 X 95 2 X 120 2 X 150 2 X 185 2 X 240 2 X 300 3 X 240 3 X 300
RESISTANCE Ω/KM 9.45 5.88 3.94 2.44 1.54 1.11 0.82 0.567 0.41 0.324 0.264 0.21 0.162 0.128 0.205 0.162 0.132 0.105 0.081 0.064 0.054 0.043
REACTANCE Ω/KM @ 50 Hz 0.0978 0.0987 0.0837 0.0808 0.0805 0.0783 0.075 0.074 0.0724 0.0712 0.0716 0.0718 0.071 0.0705 0.036 0.036 0.036 0.036 0.036 0.035 0.024 0.024
NOMINAL RATING A 32 43 55 71 94 113 133 164 196 223 249 282 326 367 392 446 498 564 652 734 978 1101
INSTALLED RATING A 14.7 19.7 25.2 32.6 43.1 51.9 61.0 75.3 89.9 102.3 114.3 129.4 149.6 168.4 179.9 204.6 228.5 258.8 299.2 336.8 448.7 505.2

CIRCUIT RATING CIRCUIT FLC

5 7 85 136 202 323 507 695 929 1,314 1,771 2,188 2,612 3,165 3,910 4,691 3,541 4,376 5,223 6,329 7,819 9,382 11,729 14,073
10 14 42 68 101 162 253 348 465 657 885 1,094 1,306 1,582 1,955 2,345 1,771 2,188 2,612 3,165 3,910 4,691 5,864 7,036
15 21 - - 67 108 169 232 310 438 590 729 871 1,055 1,303 1,564 1,180 1,459 1,741 2,110 2,606 3,127 3,910 4,691
20 28 - - - 81 127 174 232 329 443 547 653 791 977 1,173 885 1,094 1,306 1,582 1,955 2,345 2,932 3,518
25 35 - - - - 101 139 186 263 354 438 522 633 782 938 708 875 1,045 1,266 1,564 1,876 2,346 2,815
30 42 - - - - 84 116 155 219 295 365 435 527 652 782 590 729 871 1,055 1,303 1,564 1,955 2,345
35 49 - - - - - 99 133 188 253 313 373 452 559 670 506 625 746 904 1,117 1,340 1,676 2,010
40 56 - - - - - - 116 164 221 273 326 396 489 586 443 547 653 791 977 1,173 1,466 1,759
45 63 - - - - - - - 146 197 243 290 352 434 521 393 486 580 703 869 1,042 1,303 1,564
60 83 - - - - - - - - 149 185 220 267 330 396 299 369 441 534 659 791 989 1,187
72 100 - - - - - - - - - 153 183 222 274 328 248 306 366 443 547 657 821 985
90 125 - - - - - - - - - - - 177 219 263 198 245 293 354 438 525 657 788
180 250 - - - - - - - - - - - - - - - - - 177 219 263 328 394
287.5 400 - - - - - - - - - - - - - - - - - - - - 205 246

Notes:
1. This chart applies to feeder Cables having the following installation conditions:
a) Cables laid underground at depth of 900mm. (Derating Factor F d 0.97 for 300 sqmm cable, for others it is >0.97)
b) Thermal resistivity = 2.0 Km/W (Detaing factor F th = 0.9) Backfilling material to maintain 150mm gap between two layers.
c) Ground temperature = 25 Deg C (Derating factor F t = 1.03 )
d) Cu / Al Cable parameters are taken from Polycab catalogue.
e) Cables laid underground at 150mm centres and not in more than three (3) layers.Group rating factor F g = 0.43 applies for 14 nos. of cables per annexure-2A.
2. All outgoings shall be from Switch Fuse Units (SFUs)
3. Please refer Cable standard Installation drawing no E12-067.
 10080-1-ENGG-GUI-EL-002 Rev1

CABLE SIZING CALCULATION FOR LT MOTORS (IE2) - XLPE INSULATED COPPER AND XLPE INSULATED ALUMINIUM CABLES
Table no.1 (Please refer Annexure-1)
SUPPLY VOLTAGE 415 V Power Factor 0.85 Ground Temperature rating factor: (Ft) 1.03 For ground temperature 25⁰C
% MAX VOLTAGE DROP AT STARTING 15 % Power Factor at Starting 0.3 Depth of laying (Fd) 0.97 (Worst case for 300 Sqmm Cable)
% MAX VOLTAGE DROP AT FULL LOAD 5% Thermal Resistivity (Fth) 0.89 Backfill material thermal resistivity assumed to be 2.0 Km/W
Group Rating factor (Fg) 0.43 Refer Annexure-2A
Sinø 0.52678 Other rating factors 1.2 Margin considering 80-90% loading of each cable in a group (heating effect ᾀ load2)
Sinø at Starting 0.95394 Total Rating Factor 0.459

% VMAX x 10 x VSUPPLY
FORMULA: LMAX PERMISSIBLE =
√3 x IFLC x (R Cosø + X Sinø)

XLPE INSULATED COPPER AND XLPE INSULATED ALUMINIUM AND FLAT WIRE ARMOURED DIRECT BURIED
DATA FOR CABLE TYPE
COPPER ALUMINIUM
CROSS SECTION sqmm 2.5 4 10 16 25 35 50 70 95 120 150 185 240 300 2 X 95 2 X 120 2 X 150 2 X 185 2 X 240 2 X 300 3 X 150 3 X 185 3 X 240 3 X 300
RESISTANCE Ω/KM 9.45 5.88 3.94 2.44 1.54 1.11 0.82 0.567 0.41 0.324 0.264 0.21 0.162 0.128 0.205 0.162 0.132 0.105 0.081 0.064 0.088 0.070 0.054 0.043
REACTANCE Ω/KM @ 50 Hz 0.0978 0.0987 0.0837 0.0808 0.0805 0.0783 0.075 0.074 0.0724 0.0712 0.0716 0.0718 0.071 0.0705 0.036 0.036 0.036 0.036 0.036 0.035 0.024 0.024 0.024 0.024
NOMINAL RATING A 32 43 55 71 94 113 133 164 196 223 249 282 326 367 392 446 498 564 652 734 747 846 978 1101
INSTALLED RATING A 14.7 19.7 25.2 32.6 43.1 51.9 61.0 75.3 89.9 102.3 114.3 129.4 149.6 168.4 179.9 204.6 228.5 258.8 299.2 336.8 342.7 388.2 448.7 505.2
MOTOR MOTOR ST.
MOTOR FLC
RATING CURRENT MAXIMUM PERMISSIBLE ROUTE LENGTH (M)
(A)
(KW) (A)
0.55 1.6 13 913 1,439 2,119 - - - - - - - - - - - - - - - - - - - - -
1.1 2.8 24 522 822 1,211 1,889 2,836 - - - - - - - - - - - - - - - - - - -
1.5 3.8 32 385 606 892 1,392 2,090 2,762 - - - - - - - - - - - - - - - - - -
2.2 4.8 40 304 480 706 1,102 1,654 2,186 2,807 - - - - - - - - - - - - - - - - -
3 7 59 209 329 484 755 1,134 1,499 1,925 2,539 - - - - - - - - - - - - - - - -
4 8 67 183 288 424 661 993 1,312 1,684 2,222 2,785 - - - - - - - - - - - - - - -
5.5 10.5 88 139 219 323 504 756 999 1,283 1,693 2,122 2,468 2,763 - - - - - - - - - - - - -
7.5 14 118 104 164 242 378 567 750 962 1,270 1,591 1,851 2,072 2,324 2,627 2,893 - - - - - - - - - -
11 22.5 189 - - 151 235 353 466 599 790 990 1,152 1,289 1,446 1,635 1,800 1,980 2,303 2,578 2,892 - - - - - -
15 28 235 - - - 189 284 375 481 635 796 925 1,036 1,162 1,314 1,446 1,591 1,851 2,072 2,324 2,627 2,893 - - - -
18.5 34 286 - - - - 234 309 396 523 655 762 853 957 1,082 1,191 1,310 1,524 1,706 1,914 2,164 2,382 2,559 2,871 - -
22 41 344 - - - - 194 256 329 434 543 632 707 794 897 988 1,087 1,264 1,415 1,587 1,794 1,975 2,122 2,381 2,691 2,963
30 54 454 - - - - - - 250 329 413 480 537 603 681 750 825 960 1,074 1,205 1,362 1,500 1,611 1,808 2,043 2,250
37 65 546 - - - - - - - 273 343 399 446 501 566 623 685 797 893 1,001 1,132 1,246 1,339 1,502 1,698 1,869
45 79 664 - - - - - - - - 282 328 367 412 466 513 564 656 734 824 931 1,025 1,102 1,236 1,397 1,538
55 95 798 - - - - - - - - - 273 305 343 387 426 469 546 611 685 774 853 916 1,028 1,161 1,279
75 134 1126 - - - - - - - - - - - - 274 302 332 387 433 486 549 604 649 728 823 907
90 158 1327 - - - - - - - - - - - - - 256 466 513 698 769
110 194 1630 - - - - - - - - - - - - - - 379 417 569 626
132 229 1924 - - - - - - - - - - - - - - 321 354 482 531
160 278 2335 - - - - - - - - - - - - - - 265 291 397 437
200 368 3088 - - - - - - - - - - - - - - - - 300 330
225 414 3474 - - - - - - - - - - - - - - - - 267 294
250 460 3860 - - - - - - - - - - - - - - - - - 264
275 505 4246 - - - - - - - - - - - - - - - - - -
300 551 4632 - - - - - - - - - - - - - - - - - - - -

Notes:
1. This chart applies to feeder Cables having the following installation conditions:
a) Cables laid underground at depth of 900mm. (Derating Factor F d 0.97 for 300 sqmm cable, for others it is >0.97)
b) Thermal resistivity = 2.0 Km/W (Detaing factor F th = 0.9) Backfilling material to maintain 150mm gap between two layers.
c) Ground temperature = 25 Deg C (Derating factor F t = 1.03 )
d) Cu / Al Cable parameters are taken from Polycab catalogue.
e) Cables laid underground at 150mm centres and not in more than three (3) layers.Group rating factor F g = 0.43 applies for 14 nos. of cables per annexure-2A.
2. LRC for IE-2 has been considered as 840% of normal full load current, as per tolerance mentioned in IS 12615 : 2004.
3. Please refer Cable standard Installation drawing no E12-067.
4. 90kW and above motors are to be fed from Air Circuit Breaker (ACB) outgoings.