16
5.2
HOW TO DETERMINE THE POWER SUPPLY CABLE
To determine the size of the power cable for the submersible motor, the
following information is required:
- V: Rated value of input voltage (V)
- I: Current consumption of motor, indicated on the motor rating plate (A)
- L: Length of line
- Cosf: Motor power factor (indicated on the rating plate)
- Room temperature (
°
C)
- Current carrying capacity of cable
Choose the minimum cross-section from the value I of the rated current of
the motor, according to the maximum current carrying capacities of cables
indicated in Table 4. Quadripolar cables are used for cables up to a cross-
section of 35 mm˝, while unipolar cables are recommended for larger cross-
sections.
Table 4 indicates maximum current carrying capacities of cables according
to the number of lines that are connected in parallel:
just one line
direct motor starting
stator motor starting
two lines
star/delta starting
two lines in parallel in order to use lighter cables
four lines
star/delta starting with double lines.
For star/delta starting, the current in the cables is equal to the rated current
divided by 1,73.
The maximum current carrying capacities of the cables shown in Table 4
apply for room temperatures of 30
°
C. If the room temperature is different
apply the correction factor.
The final choice of the cross-section of the cable is carried out by verifying
the voltage drop along the power line, by applying the following relation:
V% = 173 x I x L x (R x cos
+ X x sen
) / V
V% voltage drop in percent (must not exceed is 5%)
I = rated current in Amperes (for star/delta starting the value is 58%)
L = lenght of line in meters (for star/delta starting the lenght is double)
cos
= power factor (indicated on the motor rating plate)
sen
= ( 1-cos2
)
R,X = resistance and reactance of cable in ohm/metre (indicated in tab.4)
V = input voltage.
The following tables define the maximum lenght of the cables depending
on the power of the motor, input voltage, the size of the cables, all at a
room temperature of 30
°
C.
TAB. 4
Electrical cables - Direct starting - 3 phase motor
1,5
2,5
4
6
10
16
25
35
60
70
95
120
150
185
240
18
24
32
41
57
76
102
126
168
213
258
300
350
392
461
16
21
28
36
50
68
89
110
146
185
224
261
305
341
401
14
19
26
33
46
61
82
101
134
170
206
240
280
314
369
15,1
9,08
5,63
3,73
2,27
1,43
0,907
0,654
0,473
0,326
0,236
0,188
0,153
0,123
0,0943
0,118
0,109
0,101
0,0955
0,0861
0,0817
0,0813
0,0753
0,101
0,0955
0,0955
0,0939
0,0928
0,0908
0,0902
Type of cable
Rated
cross-section
mm
2
Max. cable capacity
1 lines
2 lines 4 lines
A
A
A
/Km
/Km
Resistance
Reatance
R
X
178
265
439
706
1060
231
344
570
915
531
791
611
908
691
1028
127
189
313
503
755
167
248
412
660
990
378
563
834
435
847
1073
500
743
95
142
235
377
566
822
131
194
321
515
772
284
422
700
335
498
825
390
580
961
63
94
156
251
377
615
963
87
129
241
344
515
636
189
282
467
750
223
332
550
883
260
387
641
1027
51
76
127
203
305
497
780
67
99
164
263
395
642
1003
153
228
377
606
911
176
261
433
698
1045
199
296
491
787
39
59
97
156
234
382
599
926
52
77
127
204
307
499
779
117
175
290
465
899
135
201
333
534
802
155
230
381
611
917
220
240
380
400
415
220
240
380
400
415
220
240
380
400
415
220
240
380
400
415
220
240
380
400
415
220
240
380
400
415
1,9
1,7
1,1
1,0
1,0
2,7
2,5
1,6
1,5
1,4
3,6
3,3
2,1
2,0
1,9
5,4
5,0
3,1
3,0
2,9
6,6
6,1
3,8
3,6
3,5
8,5
7,8
4,9
4,7
4,5
0,5
0,75
1
1,5
2
3
0,37
0,55
0,75
1,1
1,5
2,2
HP
kW
V
A
1
1,5
2,5
4
6
10
16
25
Rated poxer
of motor
Rated
voltage
Rated
current
Cable section (mm
2
) - Quadripolar cables
Max. cable lenght with 5% voltage drop
Quadripole
Quadripole
Quadripole
Quadripole
Quadripole
Quadripole
Quadripole
Quadripole
Unipolar
Unipolar
Unipolar
Unipolar
Unipolar
Unipolar
Unipolar
