1. ≔step ‥1 21
Calculation Step-1
CALCULATE CABLE CONDUCTOR DIMENSIONS
Calculate diameter of conductors based on Iec sizes,
The first step is assigned to wire with standard cable sizes as cable area exprerssed in mm2.
Calaculate cable diamater based on cable area.
]Diamater (d= area*4/ )^.5π
≔Iec
1
⋅1.5 mm
2
≔Iec
12
⋅120 mm
2
≔Iec
13
⋅150 mm
2
PRNCOLWIDTH
6
≔Iec
3
⋅4 mm
2
≔Iec
2
⋅2.5 mm
2
≔Iec
14
⋅185 mm
2
≔Iec
15
⋅240 mm
2
≔Iec
4
⋅6 mm
2
≔Iec
6
⋅16 mm
2
≔Iec
17
⋅400 mm
2
≔Iec
16
⋅300 mm
2
≔Iec
5
⋅10 mm
2
≔Iec
7
⋅25 mm
2
≔Iec
18
⋅500 mm
2
≔Iec
11
⋅95 mm
2
≔Iec
19
⋅630 mm
2
≔Iec
8
⋅35 mm
2
≔Iec
20
⋅800 mm
2
≔Iec
9
⋅50 mm
2
≔Iec
10
⋅70 mm
2
≔Iec
21
⋅1000 mm
2
Cable Diamater (d) based on solid (not Stranded) cable area.(area).
Formula= ]Diamater (d= area*4/ )^.5π Non-Commercial Use Only
5-ampacity-IEC-upload.mcdx

2. Cable Diamater (d) based on solid (not Stranded) cable area.(area).
Formula= ]Diamater (d= area*4/ )^.5π
≔d
step
=
⎛
⎜
⎝
⋅Iec
step
―
4
π
⎞
⎟
⎠
.5
1.382
1.784
2.257
2.764
3.568
4.514
5.642
6.676
7.979
9.441
10.998
12.361
13.82
15.348
17.481
19.544
22.568
25.231
28.322
31.915
35.682
⎡
⎢
⎢
⎢
⎢
⎢
⎢
⎢
⎢
⎢
⎢
⎢
⎢
⎢
⎢
⎢
⎢
⎢
⎢
⎢
⎢
⎢
⎢
⎢
⎢⎣
⎤
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥⎦
mm ≔area
step
=⋅π
⎛
⎜
⎜
⎝
―――
⎛
⎝
d
step
⎞
⎠
2
4
⎞
⎟
⎟
⎠
1.5
2.5
4
6
10
16
25
35
50
70
95
120
150
185
240
300
400
500
630
800
1000
⎡
⎢
⎢
⎢
⎢
⎢
⎢
⎢
⎢
⎢
⎢
⎢
⎢
⎢
⎢
⎢
⎢
⎢
⎢
⎢
⎢
⎢
⎢
⎢
⎢⎣
⎤
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥⎦
mm
2
=step
1
2
3
4
5
6
7
8
9
10
11
12
⋮
⎡
⎢
⎢
⎢
⎢
⎢
⎢
⎢
⎢
⎢
⎢
⎢
⎢
⎢
⎢
⎣
⎤
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎦
Non-Commercial Use Only
5-ampacity-IEC-upload.mcdx

3. Assign the cable number, size, diamater and Area
≔Mc
,step 3
―――
area
step
mm
2≔Mc
,step 2
――
d
step
mm≔Mc
,step 0
step ≔Mc
,step 1
―――
Iec
step
mm
2
≔Mc
,0 0
“step #” ≔Mc
,0 1
“"mm2 Size ” ≔Mc
,0 2
“conductor dia-mm” ≔Mc
,0 3
“Conductor Area mm sq”
=Mc
“step #” “"mm2 Size ” “conductor dia-mm” “Conductor Area mm sq”
1 1.5 1.382 1.5
2 2.5 1.784 2.5
3 4 2.257 4
4 6 2.764 6
5 10 3.568 10
6 16 4.514 16
7 25 5.642 25
8 35 6.676 35
9 50 7.979 50
10 70 9.441 70
11 95 10.998 95
12 120 12.361 120
13 150 13.82 150
14 185 15.348 185
15 240 17.481 240
16 300 19.544 300
17 400 22.568 400
18 500 25.231 500
19 630 28.322 630
20 800 31.915 800
21 1000 35.682 1000
⎡
⎢
⎢
⎢
⎢
⎢
⎢
⎢
⎢
⎢
⎢
⎢
⎢
⎢
⎢
⎢
⎢
⎢
⎢
⎢
⎢
⎢
⎢
⎢
⎢
⎢⎣
⎤
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥⎦
Non-Commercial Use Only
5-ampacity-IEC-upload.mcdx

4. Assign Stranding factors to obtain Conductor OD based on IEC-60228 TABLE-2 CLASS 2 STRANDED
CONDUCTORS FOR Single AND MULTICORE CABLES
The concentric stranding factor is defined as the ratio of area of all stranded conductor with equivalent solid
conductor.
“Radius of each Strand =”
“Area for 1 strand =”
“Total Area for 7 strand = A1”
“Conductive Diameter of 7 strands = D1”
“Radius of overall conductor =”
“Area for overall conductor =A2”
“Diameter of overall conductor = D2”
“Stranding Factor =”
“Conductive Diameter of 7strands (D1) / Diameter of overall conductor (D2) ”
“Stranding Factor = D1/21”
“r”
“a=π r^2”
“A1=7 x π r2”
“R=r+2r = 3r”
“A2=π (3r)2”
“D2/D1”
“(9/ 7)^.5 =1.134”
0.5mm2 through 35mm2 7- strand multiply by (9/7)^.5 factor
50mm2 through 95mm2 19 strand multiply by (25/19)^.5 factor
120mm2 through 240mm2 37 strand multiply by (49/37)^.5 factor
300mm2 through 500mm2 61 strand multiply by (81/61)^.5 factor
630mm2 through 1000mm2 91 strand multiply by (121/91)^.5 factor
Non-Commercial Use Only
5-ampacity-IEC-upload.mcdx

5. Calcualte cable stranding factors for 9 strands,25 strands, 49 strands, 81 strands, and 121 strands, (nst= range of
strands 1--5, and ns = conductive area of stranded cable.
≔nst ‥1 5 ≔ns
nst
⎛
⎜
⎝
+∑
=n 1
nst
(( ⋅6 n)) 1
⎞
⎟
⎠
=nst
1
2
3
4
5
⎡
⎢
⎢
⎢
⎢
⎣
⎤
⎥
⎥
⎥
⎥
⎦
=(( +⋅2 nst 1))
2
9
25
49
81
121
⎡
⎢
⎢
⎢
⎢
⎣
⎤
⎥
⎥
⎥
⎥
⎦
=ns
nst
7
19
37
61
91
⎡
⎢
⎢
⎢
⎢
⎣
⎤
⎥
⎥
⎥
⎥
⎦
≔Dstr
step
Mc
,step 2
≔strf
nst
=――――――
(( +⋅2 nst 1))
⎛
⎜
⎝
+∑
=n 1
nst
(( ⋅6 n)) 1
⎞
⎟
⎠
.5
1.134
1.147
1.151
1.152
1.153
⎡
⎢
⎢
⎢
⎢
⎣
⎤
⎥
⎥
⎥
⎥
⎦
=Dstr
0
1.382
1.784
2.257
2.764
3.568
4.514
5.642
6.676
7.979
9.441
10.998
12.361
13.82
15.348
17.481
19.544
22.568
25.231
28.322
31.915
35.682
⎡
⎢
⎢
⎢
⎢
⎢
⎢
⎢
⎢
⎢
⎢
⎢
⎢
⎢
⎢
⎢
⎢
⎢
⎢
⎢
⎢
⎢
⎢
⎢
⎢
⎢⎣
⎤
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥⎦
Non-Commercial Use Only
5-ampacity-IEC-upload.mcdx

6. Calcualte cable diamaters with stranding factors applied for for 9 strands,25 strands, 49 strands, 81 strands, and 121
strands.
≔Dstr
step
if
⎛
⎜
⎝
,,<step 22 ⋅d
step
⎛
⎜
⎝
――
121
91
⎞
⎟
⎠
.5
Dstr
step
⎞
⎟
⎠
≔Dstr
step
if
⎛
⎜
⎝
,,<step 18 ⋅d
step
⎛
⎜
⎝
――
81
61
⎞
⎟
⎠
.5
Dstr
step
⎞
⎟
⎠
≔Dstr
step
if
⎛
⎜
⎝
,,<step 15 ⋅d
step
⎛
⎜
⎝
――
49
37
⎞
⎟
⎠
.5
Dstr
step
⎞
⎟
⎠
≔Dstr
step
if
⎛
⎜
⎝
,,<step 11 ⋅d
step
⎛
⎜
⎝
――
25
19
⎞
⎟
⎠
.5
Dstr
step
⎞
⎟
⎠
≔Dstr
step
if
⎛
⎜
⎝
,,<step 8 ⋅d
step
⎛
⎜
⎝
―
9
7
⎞
⎟
⎠
.5
Dstr
step
⎞
⎟
⎠
≔Dstr
step
if⎛
⎝
,,<step 0 d
step
Dstr
step
⎞
⎠
=Dstr
0 ―
1
m
1.567
2.023
2.559
3.134
4.046
5.118
6.397
7.657
9.152
10.829
12.657
14.225
15.904
17.662
20.144
22.521
26.005
29.095
32.659
36.802
41.146
⎡
⎢
⎢
⎢
⎢
⎢
⎢
⎢
⎢
⎢
⎢
⎢
⎢
⎢
⎢
⎢
⎢
⎢
⎢
⎢
⎢
⎢
⎢
⎢
⎢
⎢
⎢
⎣
⎤
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎦
mm
Non-Commercial Use Only
5-ampacity-IEC-upload.mcdx

7. Table for cable step. area, solid conducor diameter, and stranded conductor diameters.
≔Mc
,step 4
―――
Dstr
step
mm
≔Mc
,0 4
“Stranded Conductor Dia mm”
=Mc
“step #” “"mm2 Size ” “conductor dia-mm” “Conductor Area mm sq” “Stranded Conductor Dia mm”
1 1.5 1.381977 1.5 1.567014
2 2.5 1.784124 2.5 2.023007
3 4 2.256758 4 2.558923
4 6 2.763953 6 3.134028
5 10 3.568248 10 4.046013
6 16 4.513517 16 5.117847
7 25 5.641896 25 6.397309
8 35 6.675581 35 7.657417
9 50 7.978846 50 9.152364
10 70 9.440697 70 10.829223
11 95 10.99808 95 12.656512
12 120 12.360774 120 14.224692
13 150 13.819766 150 15.903689
14 185 15.347616 185 17.661928
15 240 17.480775 240 20.143655
16 300 19.5441 300 22.521291
17 400 22.567583 400 26.005347
18 500 25.231325 500 29.094577
19 630 28.322092 630 32.658582
20 800 31.915382 800 36.802053
21 1000 35.682482 1000 41.145946
⎡
⎢
⎢
⎢
⎢
⎢
⎢
⎢
⎢
⎢
⎢
⎢
⎢
⎢
⎢
⎢
⎢
⎢
⎢
⎢
⎢
⎢
⎢
⎢
⎢
⎢⎣
⎤
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥⎦
Non-Commercial Use Only
5-ampacity-IEC-upload.mcdx

8. Calculate cable diamter with insulation thickness added
.
Calculation Step 2
CALCULATE CABLE INSULATION DIMENSIONS
Add insulation thickness based on conductor sizes mm accordance with ICEA WC-70-1999 Table 3-4. using column B for 3-conductor cables as follows.
Non-Commercial Use Only
5-ampacity-IEC-upload.mcdx

9. ≔a1 1 ≔Dinsul
a1
+Dstr
a1
⋅⋅2 .7 mm =Dinsul
a1
2.967 mm
≔a2 ‥2 4
≔Dinsul
a2
+Dstr
a2
⋅⋅2 .8 mm
=Dinsul
a2
3.623
4.159
4.734
⎡
⎢
⎢
⎣
⎤
⎥
⎥
⎦
mm
≔a3 ‥5 6 ≔Dinsul
a3
+Dstr
a3
⋅⋅2 1 mm
=Dinsul
a3
6.046
7.118
⎡
⎢⎣
⎤
⎥⎦
mm
≔a4 ‥7 8 ≔Dinsul
a4
+Dstr
a4
⋅⋅2 1.2 mm =Dinsul
a4
8.797
10.057
⎡
⎢⎣
⎤
⎥⎦
mm
≔a5 ‥9 10 ≔Dinsul
a5
+Dstr
a5
⋅⋅2 1.4 mm =Dinsul
a5
11.952
13.629
⎡
⎢⎣
⎤
⎥⎦
mm
≔a6 ‥11 12 ≔Dinsul
a6
+Dstr
a6
⋅⋅2 1.6 mm
=Dinsul
a6
15.857
17.425
⎡
⎢⎣
⎤
⎥⎦
mm
≔a7 13 ≔Dinsul
a7
+Dstr
a7
⋅⋅2 1.8 mm =Dinsul
a7
19.504 mm
≔a8 14 ≔Dinsul
a8
+Dstr
a8
⋅⋅2 2 mm =Dinsul
a8
21.662 mm
≔a9 15 ≔Dinsul
a9
+Dstr
a9
⋅⋅2 2.2 mm =Dinsul
a9
24.544 mm
≔a10 16 ≔Dinsul
a10
+Dstr
a10
⋅⋅2 2.4 mm =Dinsul
a10
27.321 mm
≔a11 17 ≔Dinsul
a11
+Dstr
a11
⋅⋅2 2.6 mm =Dinsul
a11
31.205 mm
≔a12 ‥18 21 ≔Dinsul
a12
+Dstr
a12
⋅⋅2 2.8 mm =Dinsul
a12
34.695
38.259
42.402
46.746
⎡
⎢
⎢
⎢
⎣
⎤
⎥
⎥
⎥
⎦
mm
0
2.967
3.623
⎡
⎢
⎢
⎤
⎥
⎥ Non-Commercial Use Only
5-ampacity-IEC-upload.mcdx

10. =Dinsul
0
2.967
3.623
4.159
4.734
6.046
7.118
8.797
10.057
11.952
13.629
15.857
17.425
19.504
21.662
24.544
27.321
31.205
34.695
38.259
42.402
46.746
⎡
⎢
⎢
⎢
⎢
⎢
⎢
⎢
⎢
⎢
⎢
⎢
⎢
⎢
⎢
⎢
⎢
⎢
⎢
⎢
⎢
⎢
⎢
⎢
⎢
⎢⎣
⎤
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥⎦
mm
Calculation Step-3
CALCULATE CABLE CAPACITANCE
Assign values of permittivity of free space eo = 10^-9/36p, Non-Commercial Use Only
5-ampacity-IEC-upload.mcdx

11. Calculation Step-3
CALCULATE CABLE CAPACITANCE
Assign values of permittivity of free space eo = 10^-9/36p,
Relative permittivity of insulation materials = 5 .
Select phase to Neutral Voltage
Calculate capacitance pF of the cables
Calculate Charging Current Amps of the cables.
≔f ⋅50 Hz ≔v ――――
⋅440 volt
‾‾3
≔εr 3.5
≔εo ⋅――
10
−9
⋅36 π
―
F
m
≔C
step
――――――
⋅⋅⋅2 π εo εr
ln
⎛
⎜
⎜
⎜⎝
――――
Dinsul
step
d
step
⎞
⎟
⎟
⎟⎠
≔I
step
⋅⋅⋅⋅2 π f v C
step
≔Mcap
,step 2
―――
I
step
―――
A
⋅1000 m
≔Mcap
,step 0
―――
Iec
step
mm
2
≔Mcap
,step 1
――
C
step
⎛
⎜
⎝
――
pF
m
⎞
⎟
⎠
≔Mcap
,0 0
“MM^2 Size” ≔Mcap
,0 2
“chanrgmmg current A /1000 m”
≔Mcap
,0 1
“capacitance pF/m”
TABLE -2
COLMUN -1 CABLE SIZE; MM^2,COLUMN-2 CABLE CAPACITANCE PICO FARAD PER METER, COLUMN-3 CABLE Charging CURRENT AMPS PER 1000 METERS
=Mcap
“MM^2 Size” “capacitance pF/m” “chanrgmmg current A /1000 m”
1.5 254.495 0.02
2.5 274.493 0.022
4 318.07 0.025
6 361.344 0.029
10 368.738 0.029
16 426.854 0.034
25 437.715 0.035
35 474.424 0.038
50 481.137 0.038
70 529.552 0.042
95 531.473 0.042
120 566.299 0.045
150 564.419 0.045
185 564.268 0.045
240 572.988 0.046
300 580.444 0.046
400 599.998 0.048
500 610.506 0.049
630 646.584 0.052
800 684.402 0.055
1000 719.984 0.057
⎡
⎢
⎢
⎢
⎢
⎢
⎢
⎢
⎢
⎢
⎢
⎢
⎢
⎢
⎢
⎢
⎢
⎢
⎢
⎢
⎢
⎢
⎢
⎢
⎢
⎢⎣
⎤
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥⎦
Power Cable Capacity Calculations Non-Commercial Use Only
5-ampacity-IEC-upload.mcdx

12. Power Cable Capacity Calculations
THE BASIS OF CABLE AMPACITY IS THE STEADY STATE AT MAXIMUM insulations Operating TEMPERATURE
REACHED in THE CABLE DUE TO HEAT PRODUCED in THE CABLE AND THE HEAT DISSIPATED TO THE
Surroundings.
Heat is produced at following parts mm the cable system.
1-dielectric losses
2-cable conductor losses
3-metallic sheathing losses
4-cable armoring or steel pipe losses
Calculation Step-1
CALCULATE CABLE CONDUCTOR LOSSES
CABLE CONDUCTOR LOSSES ARE BASED ON THREE SOURCES
a) Conductor I2 R loss Rdc(at operating temp)
b) Skin effect losses Ys(Skin effect)
c) Proximity effect losses Yp(proximity effect)
Rac=Rdc(at operating temp)+Ys(Skin effect)+ Yp(proximity effect)
Calculation Step-1a
CALCULATE CABLE CONDUCTOR I2R LOSSES
Conductor I2 R loss
= copper resistivity Wmeterρ0
.002 =stranding factor per ASTM B8-Table 4
= area of conductor mm2area
=copper resistance coefficient at 20 deg Cα20
: =Maximum conductor temperature ( limited by termination or insulation temperature).θcmax
= Calculated dc resistance of wire ( step).Rdc
step
≔Rdc
step
⋅――――
⋅ρ0 ((1.02))
area
step
(( +1 ⋅α20 (( −θcmax ⋅(( +273.15 20)) K))))
≔α20 ―――
.00393
K
≔θcmax ⋅(( +273.15 70)) K
≔ρ0 ⋅⋅⋅1.7241 10
−8
Ω m ≔Rdc
step
⋅――――
⋅ρ0 ((1.02))
area
step
(( +1 ⋅α20 (( −θcmax ⋅(( +273.15 20)) K))))
=Rdc
2
2.565 ―――
Ω
⋅1000 ft
Calculation Step-1b
CALCULATE CABLE CONDUCTOR SKIN LOSSES
Non-Commercial Use Only
5-ampacity-IEC-upload.mcdx

13. Calculation Step-1b
CALCULATE CABLE CONDUCTOR SKIN LOSSES
SKmm and PROXIMITY EFECTS:
Cable conductors carrying alternating currents are influenced by self and mutual induction effects resulting mm increase of of resistance because current does not distribute itself evenly over the cross section of each conductor.
≔μ0 ⋅⋅⋅4 π 10
−7
―
H
m
≔μr 1
≔Cs 1 ≔xs
step
⎛
⎜
⎜⎝
―――――
⋅⋅⋅⋅2 μ0 μr f Cs
Rdc
step
⎞
⎟
⎟⎠
.5
≔Ys
step
―――――――
⎛
⎝
xs
step
⎞
⎠
4
+192 ⋅0.8 ⎛
⎝
xs
step
⎞
⎠
4
Calculation Step-1c
CALCULATE CABLE CONDUCTOR PROXIMITY EFFECT LOSSES
PROXIMITY EFECTS:
Cable conductors carrying alternating currents are influenced by self and mutual induction effects resulting mm increase of of resistance because current does not distribute itself evenly over the cross section of each conductor.
≔Cp .8 ≔xp
step
⎛
⎜
⎜⎝
―――――
⋅⋅⋅⋅2 μ0 μr f Cp
Rdc
step
⎞
⎟
⎟⎠
.5
≔Yp
step
⋅⋅
⎛
⎜
⎜
⎜⎝
―――――――
⎛
⎝
xp
step
⎞
⎠
4
+192 ⋅0.8 ⎛
⎝
xp
step
⎞
⎠
4
⎞
⎟
⎟
⎟⎠
⎛
⎜
⎜
⎜⎝
――――
d
step
Dinsul
step
⎞
⎟
⎟
⎟⎠
2 ⎛
⎜
⎜
⎜
⎜
⎜
⎝
+
⎛
⎜
⎜
⎜⎝
⋅0.312
⎛
⎜
⎜
⎜⎝
――――
d
step
Dinsul
step
⎞
⎟
⎟
⎟⎠
2 ⎞
⎟
⎟
⎟⎠
―――――――――
1.18
+―――――――
⎛
⎝
xp
step
⎞
⎠
4
+192 ⋅0.8 ⎛
⎝
xp
step
⎞
⎠
4
0.27
⎞
⎟
⎟
⎟
⎟
⎟
⎠
Calculation Step-1d
CALCULATE TOTAL CABLE CONDUCTOR AC RESISTANCE
Total conductor losses consist of resistance losses , Skin effect losses and proximity losses.
≔Rac
step
⋅Rdc
step
⎛
⎝
++1 Ys
step
Yp
step
⎞
⎠
≔Rac
step
⋅Rdc
step
⎛
⎝
++1 Ys
step
Yp
step
⎞
⎠
Calculation Step-2
CALCULATE TOTAL CABLE DIELECTRIC LOSSES.
The cable insulation medium gets polarized when voltage is applied to the conductor. The alternating voltage source mm the conductor causes insulation medium to be polarized mm alternating polarities. The energy loss mm alternating polarization
is called dielectric loss.
Non-Commercial Use Only
5-ampacity-IEC-upload.mcdx

14. Calculation Step-2
CALCULATE TOTAL CABLE DIELECTRIC LOSSES.
The cable insulation medium gets polarized when voltage is applied to the conductor. The alternating voltage source mm the conductor causes insulation medium to be polarized mm alternating polarities. The energy loss mm alternating polarization
is called dielectric loss.
≔Wd
step
⋅⋅⋅⋅⋅2 π f C
step
v
2
.008
≔Mdielectric
,step 0
―――
Iec
step
mm
2 ≔Mdielectric
,0 0
“Iec ” ≔Mdielectric
,step 1
⋅Wd
step
―――
⋅1000 m
W
=Wd
1
0.041 ―――
W
⋅1000 m
≔Mdielectric
,0 2
“ AC resistance ohm /1000m” ≔Mdielectric
,step 2
―――
Rac
step
―――
Ω
⋅1000 m
≔Mdielectric
,0 1
“Dielectric loss W/1000m”
TABLE -3
COLMUN -1 CABLE SIZE; Iec ,
COLUMN-2 CABLE DIELECTRIC LOSS WATTS PER 1000 METER,
COLUMN-3 CABLE AC RESISTANCE OHMS PER 1000 METERS
=Mdielectric
“Iec ” “Dielectric loss W/1000m” “ AC resistance ohm /1000m”
1.5 0.041 14.028
2.5 0.045 8.417
4 0.052 5.26
6 0.059 3.507
10 0.06 2.104
16 0.069 1.315
25 0.071 0.842
35 0.077 0.601
50 0.078 0.421
70 0.086 0.301
95 0.086 0.222
120 0.092 0.176
150 0.092 0.142
185 0.092 0.115
240 0.093 0.09
300 0.094 0.073
400 0.097 0.056
500 0.099 0.047
630 0.105 0.039
800 0.111 0.033
1000 0.117 0.029
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⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥⎦
Calculation Step-3 Non-Commercial Use Only
5-ampacity-IEC-upload.mcdx

15. Calculation Step-3
CALCULATE TOTAL THERMAL RESISTANCE TO HEAT DISSIPATION
The resistance to heat dissipation consist of following thermal resistance.
a) Cable insulation T1
b) Cable binder tape and corrugated metallic armor T2
c) Cable metallic outer jacket T3
d) mm case of direct Buried cable , the thermal resistance of earth to the outer atmosphere. T4
Calculation Step-3a (T1)
CALCULATE TOTAL THERMAL RESISTANCE TO HEAT DISSIPATION THROUGH CABLE INSUALTION MEDIUM.
The cable insulation resistance to heat dissipation from conductor heat is calculated similar to heat transfer through insulated cylinder with inner diameter d step, outer diameter D step and thermal resistivity p and is given by following equation
= Thermal resistivity of cable insulation medium..ρt
≔T1
step
⋅――
ρt
⋅2 π
⎛
⎜
⎜
⎜⎝
ln
⎛
⎜
⎜
⎜⎝
+1 ――――
−D
step
d
step
d
step
⎞
⎟
⎟
⎟⎠
⎞
⎟
⎟
⎟⎠
≔rcore1 1 ≔rcore2 1
≔rcore3 1
≔D3core ―――――――――――――――――――――
⋅⋅(( +rcore1 rcore2)) (( +rcore1 rcore3)) (( +rcore2 rcore3))
⋅2 (( ⋅(( ⋅⋅rcore1 rcore2 rcore3)) (( ++rcore1 rcore2 rcore3))))
.5
=D3core 2.309
≔t
step
――――――――
⎛
⎝
−Dinsul
step
Dstr
step
⎞
⎠
2≔Dbtape
step
+⋅Dinsul
step
2.309 ⋅.21 mm
≔t1
step
+――――――――
⎛
⎝
−Dinsul
step
Dstr
step
⎞
⎠
2
――――――――――
⎛
⎝
−Dbtape
step
⋅2 Dinsul
step
⎞
⎠
2 ≔G
step
⋅
⎛
⎜
⎜
⎜⎝
+0.85 ⋅0.2
⎛
⎜
⎜
⎜⎝
−⋅2 ―――
t1
step
t
step
1
⎞
⎟
⎟
⎟⎠
⎞
⎟
⎟
⎟⎠
ln
⎛
⎜
⎜
⎜⎝
+⋅
⎛
⎜
⎜
⎜⎝
−8.3 ⋅2.2
⎛
⎜
⎜
⎜⎝
⎛
⎜
⎜
⎜⎝
−⋅2 ―――
t1
step
t
step
1
⎞
⎟
⎟
⎟⎠
⎞
⎟
⎟
⎟⎠
⎞
⎟
⎟
⎟⎠
⎛
⎜
⎜
⎜⎝
―――
t
step
Dstr
step
⎞
⎟
⎟
⎟⎠
1
⎞
⎟
⎟
⎟⎠
≔ρi ⋅5 ――
⋅K m
W
≔ρf ⋅5 ――
⋅K m
W ≔T1
step
+⋅――
ρi
⋅2 π
G
step
⋅⋅.031 (( −ρi ρf)) e
―――――
⋅−.67 t1
step
Dstr
step
Non-Commercial Use Only
5-ampacity-IEC-upload.mcdx

16. Calculation Step-3b (T2)
CALCULATE TOTAL THERMAL RESISTANCE TO HEAT DISSIPATION THROUGH CABLE METALLIC SHEATH ARMOR MEDIUM.
The cable insulation resistance to heat dissipation from conductor heat is calculated similar to heat transfer through insulated cylinder with inner diameter d step, outer diameter D step and thermal resistivity p and is given by following equation.
= Thermal resistivity of aluminum armor medium..ρAL
≔T2
step
⋅――
ρAL
⋅2 π
⎛
⎜
⎜
⎜⎝
ln
⎛
⎜
⎜
⎜⎝
+1 ――――――
⋅2 t2
step
DPVCsheath
step
⎞
⎟
⎟
⎟⎠
⎞
⎟
⎟
⎟⎠
=Dbtape
0
7.061
8.576
9.813
11.141
14.17
16.645
20.523
23.433
27.808
31.68
36.823
⋮
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⎢
⎢
⎢
⎢
⎢
⎢
⎢
⎢
⎢
⎢
⎢
⎣
⎤
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎦
mm
Non-Commercial Use Only
5-ampacity-IEC-upload.mcdx

17. ≔DPVCsheath
step
⎛
⎝
if⎛
⎝
,,>Dbtape
step
⋅22 mm +Dbtape
step
⋅⋅2 2.4 mm Dbtape
step
⎞
⎠
⎞
⎠
≔DPVCsheath
step
⎛
⎝
if⎛
⎝
,,<Dbtape
step
⋅22 mm +Dbtape
step
⋅⋅2 2 mm Dbtape
step
⎞
⎠
⎞
⎠
≔DPVCsheath
step
⎛
⎝
if⎛
⎝
,,<Dbtape
step
⋅18 mm +Dbtape
step
⋅⋅2 1.6 mm Dbtape
step
⎞
⎠
⎞
⎠
≔DPVCsheath
step
⎛
⎝
if⎛
⎝
,,<Dbtape
step
⋅14 mm +Dbtape
step
⋅⋅2 1.3 mm Dbtape
step
⎞
⎠
⎞
⎠
≔DPVCsheath
step
⎛
⎝
if⎛
⎝
,,<Dbtape
step
⋅9 mm +Dbtape
step
⋅⋅2 1 mm Dbtape
step
⎞
⎠
⎞
⎠
≔DPVCsheath
step
+⎛
⎝
+⋅0.08 Dbtape
step
⋅.4 mm⎞
⎠
Dbtape
step
≔t2
step
――――――――――
−DPVCsheath
step
Dbtape
step
2
≔ρAL ―――
⋅⋅1 K m
⋅273 W
≔T2
step
⋅――
ρAL
⋅2 π
⎛
⎜
⎜
⎜⎝
ln
⎛
⎜
⎜
⎜⎝
+1 ――――――
⋅2 t2
step
DPVCsheath
step
⎞
⎟
⎟
⎟⎠
⎞
⎟
⎟
⎟⎠
Non-Commercial Use Only
5-ampacity-IEC-upload.mcdx

18. Calculation Step-3c (T3)
CALCULATE TOTAL THERMAL RESISTANCE TO HEAT DISSIPATION THROUGH CABLE OUTER JACKET MEDIUM.
The cable outer jacket resistance to heat dissipation from cable metallic armor sheath is calculated similar to heat transfer through insulated cylinder with inner diameter d step, outer diameter D step and thermal resistivity p and is given by following
equation.
= Thermal resistivity of aluminum armor medium..ρAL
=DPVCsheath
0
8.026
9.662
10.998
12.432
15.704
18.377
22.565
25.707
30.433
34.614
40.169
44.079
49.264
54.646
61.832
68.758
78.444
87.145
96.033
106.366
117.198
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⎢
⎢
⎢
⎢
⎢
⎢
⎢
⎢
⎢
⎢
⎢⎣
⎤
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥⎦
mm
≔Douter DPVCsheath
Non-Commercial Use Only
5-ampacity-IEC-upload.mcdx

19. ≔Douter
step
⎛
⎝
if⎛
⎝
,,<DPVCsheath
step
⋅6.00 in +DPVCsheath
step
⋅⋅2 .110 in Douter
step
⎞
⎠
⎞
⎠
≔Douter
step
⎛
⎝
if⎛
⎝
,,<DPVCsheath
step
⋅3.00 in +DPVCsheath
step
⋅⋅2 .095 in Douter
step
⎞
⎠
⎞
⎠
≔Douter
step
⎛
⎝
if⎛
⎝
,,<DPVCsheath
step
⋅2.25 in +DPVCsheath
step
⋅⋅2 .080 in Douter
step
⎞
⎠
⎞
⎠
≔Douter
step
⎛
⎝
if⎛
⎝
,,<DPVCsheath
step
⋅1.5 in +DPVCsheath
step
⋅⋅2 .065 in Douter
step
⎞
⎠
⎞
⎠
≔Douter
step
⎛
⎝
if⎛
⎝
,,<DPVCsheath
step
⋅0.75 in +DPVCsheath
step
⋅⋅2 .050 in Douter
step
⎞
⎠
⎞
⎠
≔Mconstr
,step 0
step ≔Mconstr
,step 1
―――
Iec
step
mm
2
≔Mconstr
,step 2
――――
Dinsul
step
mm
≔Mconstr
,step 3
――――
Dbtape
step
mm
≔Mconstr
,step 4
――――――
DPVCsheath
step
mm
≔Mconstr
,0 0
“step #” ≔Mconstr
,0 1
“Iec #” ≔Mconstr
,0 2
“OD over insul- mm” ≔Mconstr
,0 3
“OD over beddmmg tape-mm ”
≔Mconstr
,0 4
“OD Over Al aromor-mm”
Non-Commercial Use Only
5-ampacity-IEC-upload.mcdx

20. =Mconstr
“step #” “Iec #” “OD over insul- mm” “OD over beddmmg tape-mm ” “OD Over Al aromor-mm” “OD over outer jacket-mm”
1 1.5 2.967 7.061 8.026 10.566
2 2.5 3.623 8.576 9.662 12.202
3 4 4.159 9.813 10.998 13.538
4 6 4.734 11.141 12.432 14.972
5 10 6.046 14.17 15.704 18.244
6 16 7.118 16.645 18.377 20.917
7 25 8.797 20.523 22.565 25.867
8 35 10.057 23.433 25.707 29.009
9 50 11.952 27.808 30.433 33.735
10 70 13.629 31.68 34.614 37.916
11 95 15.857 36.823 40.169 44.233
12 120 17.425 40.444 44.079 48.143
13 150 19.504 45.244 49.264 53.328
14 185 21.662 50.227 54.646 58.71
15 240 24.544 56.881 61.832 66.658
16 300 27.321 63.295 68.758 73.584
17 400 31.205 72.263 78.444 84.032
18 500 34.695 80.32 87.145 92.733
19 630 38.259 88.549 96.033 101.621
20 800 42.402 98.116 106.366 111.954
21 1000 46.746 108.146 117.198 122.786
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⎤
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⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥⎦
Non-Commercial Use Only
5-ampacity-IEC-upload.mcdx

21. ≔t3
step
――――――――――
−Douter
step
DPVCsheath
step
2
≔T3
step
⋅――
ρi
⋅2 π
⎛
⎜
⎜
⎜⎝
ln
⎛
⎜
⎜
⎜⎝
+1 ――――
⋅2 t3
step
Douter
step
⎞
⎟
⎟
⎟⎠
⎞
⎟
⎟
⎟⎠
Calculation Step-3d(T4)
CALCULATE TOTAL THERMAL RESISTANCE TO HEAT DISSIPATION THROUGH Surrounding MEDIUM.
The cable outer jacket resistance to heat dissipation from cable outer jacket is calculated similar to heat transfer through buried pipe mm thermally resistant soil.
= Thermal resistivity of aluminum armor medium..ρAL
u = , = soil thermal resistivity, ,――
⋅2 L
De
ρs ――
⋅K cm
W
= external diameter if the cable=De ⋅72.9 mm
L = depth of burial of the center of the cable, Wt= Total loses inside the cable (W/m)
≔θambient +⋅30 K ⋅273 K ≔θcmax ⋅(( +273.15 75)) K
≔Δθ −θcmax θambient
≔ρs ⋅150 ――
⋅K cm
W
≔L ⋅1 m =Δθ 45.15 K ≔λ2 0 ≔λ1 .01
≔T4
step
⋅――
ρs
⋅2 π
ln
⎛
⎜
⎜
⎜⎝
+――――
⋅2 L
Dinsul
step
‾‾‾‾‾‾‾‾‾‾‾‾‾‾
−―――――
(( ⋅2 L))
2
⎛
⎝
Dinsul
step
⎞
⎠
2
1
⎞
⎟
⎟
⎟⎠
Non-Commercial Use Only
5-ampacity-IEC-upload.mcdx

22. Calculation Step-4a
CALCULATE CABLE AMPACITY BASED ON HEAT GENERATION mm THE CABLE BY RESISTANCE, CAPACITANCE LOSSES AND HEAT DISSIPATION THROUGH
CABLE insulation, ARMOR, OUTER JACKET AND Surrounding MEDIUM.
The cable outer jacket resistance to heat dissipation from cable outer jacket is calculated similar to heat transfer through buried pipe mm thermally resistant soil.
= Thermal resistivity of aluminum armor medium..ρAL
=―――――
⋅25000 1.25
⋅11 1.732
1640.248
≔nc 3
≔Amp
step
⎛
⎜
⎜
⎜⎝
――――――――――――――――――――――――――――
−Δθ ⋅Wd
step
⎛
⎝
+⋅.5 T1
step
⋅nc ⎛
⎝
++T2
step
T3
step
T4
step
⎞
⎠
⎞
⎠
++⋅Rac
step
T1
step
⎛
⎝
⋅⋅⋅nc Rac
step
⎛⎝ +1 λ1
⎞⎠ T2
step
⎞
⎠
⋅⋅⋅nc Rac
step
⎛⎝ ++1 λ1 λ2
⎞⎠ ⎛
⎝
+T3
step
T4
step
⎞
⎠
⎞
⎟
⎟
⎟⎠
.5
=Amp
0
22.143
29.254
38.041
47.813
63.117
82.585
104.898
127.833
155.652
189.9
224.031
257.666
290.882
325.949
375.148
423.269
492.723
552.142
623.718
703.066
782.222
⎡
⎢
⎢
⎢
⎢
⎢
⎢
⎢
⎢
⎢
⎢
⎢
⎢
⎢
⎢
⎢
⎢
⎢
⎢
⎢
⎢
⎢
⎢
⎢
⎢
⎢⎣
⎤
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥⎦
A =Iec
0
1.5
2.5
4
6
10
16
25
35
50
70
95
120
150
185
240
300
400
500
630
800
1000
⎡
⎢
⎢
⎢
⎢
⎢
⎢
⎢
⎢
⎢
⎢
⎢
⎢
⎢
⎢
⎢
⎢
⎢
⎢
⎢
⎢
⎢
⎢
⎢
⎢
⎢⎣
⎤
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥
⎥⎦
⋅mm mm
Non-Commercial Use Only
5-ampacity-IEC-upload.mcdx

23. Non-Commercial Use Only
5-ampacity-IEC-upload.mcdx

24. Non-Commercial Use Only
5-ampacity-IEC-upload.mcdx

25. The heat loss through convection is given by Newton's law of cooling.
≔Wconvection ⋅⋅hconvection Acable
⎛⎝ −θcable θambient
⎞⎠
Thermal resistance for convection =
≔Tconvection ――――――
⎛⎝ −θcable θambient
⎞⎠
W
≔Tconvection ――――
1
⋅hconv Acable
The heat loss through radiation exchange is given by Boltzmann's law of cooling.
≔Tradiation ――――――
⎛⎝ −θcable θambient
⎞⎠
Wrad
Non-Commercial Use Only
5-ampacity-IEC-upload.mcdx

26. ≔Tradiation ――――――
⎛⎝ −θcable θambient
⎞⎠
Wrad
≔Tradiation ――――
1
⋅hrad Acable
≔Wradiation ⋅⋅ε σB Acable
⎛
⎝ −θcable
4
θambient
4 ⎞
⎠
≔hrad ⋅⋅⋅ε σB
⎛⎝ +θcable θambient
⎞⎠
⎛
⎝ +θcable
2
θambient
2 ⎞
⎠
The energy balance for the cables mm air, under sunlight, and supported on the
structural supports is given by following
≔Wt ++Wconv Wcond Wrad
= natural convection heat transfer rate between the cable outside surface andWconv
the surroundings medium per unit length.
= conductive heat transfer rate mm the medium surrounding the cableWcond
= thermal radiation heat transfer rate from cable surfaceWrad
≔Wt ++Wconv Wcond Wrad
≔Wrad ⋅⋅σ De hconv
⎛⎝ −θcable θamb
⎞⎠
≔Wrad ++⋅⋅σ De hconv
⎛⎝ −θcable θam
⎞⎠ ⋅⋅σ De H ⋅⋅⋅⋅π De εs σB
⎛
⎝ −θcable
4
θambient
4 ⎞
⎠
s = solar absorption coefficient
= connective heat transfer coefficient W/m^2*K^-1hconv
= Cable external Diameter , mDe
= Cable surface temperature, Kθcable
= ambient temperature Kθamb
immensity of solar radiation W/m^2
:emissivity of the cable outer coveringεs
=Stefan-Boltzman constant, =σB ⋅⋅5.67 10
−8
――
⋅W K
4
m
2
= Select a temperature about midway between maximum and minimum expectedθm
temperatures for the surface of the cable .
≔T4free ―――――――――――――
1
⋅π De
⎛
⎜ +――
1.05
―
1
⋅4.2 ⎛⎝ ⋅εs
⎛⎝ +1 ⋅0.0167 θm
⎞⎠⎞⎠
⎞
⎟ Non-Commercial Use Only
5-ampacity-IEC-upload.mcdx

27. ≔T4free ―――――――――――――
1
⋅π De
⎛
⎜
⎜
⎝
+――
1.05
De
―
1
4
⋅4.2 ⎛⎝ ⋅εs
⎛⎝ +1 ⋅0.0167 θm
⎞⎠⎞⎠
⎞
⎟
⎟
⎠
≔T4forced ⋅π De
⎛
⎜
⎝
+⋅2.87
‾‾‾
―
U
De
⋅4.2 ⎛⎝ ⋅εs
⎛⎝ +1 ⋅0.0167 θm
⎞⎠⎞⎠
⎞
⎟
⎠
≔εs .9 ≔θm 50 ≔De .0729 ≔nc 3
≔T4free
step
―――――――――――――――――――――
⋅1 ――
⋅K m
2
W
⋅⋅π ⎛
⎝
⋅Dinsul
step
nc⎞
⎠
⎛
⎜
⎜
⎜
⎜
⎝
+―――――
1.05
⎛
⎜
⎜⎝
――――
Dinsul
step
m
⎞
⎟
⎟⎠
―
1
4
⋅4.2 ⎛⎝ ⋅εs
⎛⎝ +1 ⋅0.0167 θm
⎞⎠⎞⎠
⎞
⎟
⎟
⎟
⎟
⎠
≔T4
step
T4free
step
≔Amp
step
⎛
⎜
⎜
⎜⎝
――――――――――――――――――――――――――――
−Δθ ⋅Wd
step
⎛
⎝
+⋅.5 T1
step
⋅nc ⎛
⎝
++T2
step
T3
step
T4
step
⎞
⎠
⎞
⎠
++⋅Rac
step
T1
step
⎛
⎝
⋅⋅⋅nc Rac
step
⎛⎝ +1 λ1
⎞⎠ T2
step
⎞
⎠
⋅⋅⋅nc Rac
step
⎛⎝ ++1 λ1 λ2
⎞⎠ ⎛
⎝
+T3
step
T4
step
⎞
⎠
⎞
⎟
⎟
⎟⎠
.5
≔θambient +⋅45 K ⋅273 K ≔θcmax ⋅(( +273.15 90)) K
≔Δθ −θcmax θambient
≔Depth ‥1 3
≔ρs ⋅250 ――
⋅K cm
W
≔L ⋅1 m =Δθ 45.15 K ≔λ2 0 ≔λ1 .01
≔L
Depth
⋅L Depth
≔T4
,step Depth
⋅――
ρs
⋅2 π
ln
⎛
⎜
⎜
⎜
⎜⎝
+――――
⋅2 L
Depth
Dinsul
step
‾‾‾‾‾‾‾‾‾‾‾‾‾‾
−―――――
⎛
⎝
⋅2 L
Depth
⎞
⎠
2
⎛
⎝
Dinsul
step
⎞
⎠
2
1
⎞
⎟
⎟
⎟
⎟⎠
Non-Commercial Use Only
5-ampacity-IEC-upload.mcdx

28. ⋅2 π ⎜
⎜⎝
Dinsul
step
⎛
⎝
Dinsul
step
⎞
⎠
2 ⎟
⎟⎠
≔Cable 16
≔nc 3 =Iec
Cable
300 mm
2
≔AmpD
,Cable Depth
⎛
⎜
⎜
⎜⎝
―――――――――――――――――――――――――――――――
−Δθ ⋅Wd
Cable
⎛
⎝
+⋅.5 T1
Cable
⋅nc ⎛
⎝
++T2
Cable
T3
Cable
T4
,Cable Depth
⎞
⎠
⎞
⎠
++⋅Rac
Cable
T1
Cable
⎛
⎝
⋅⋅⋅nc Rac
Cable
⎛⎝ +1 λ1
⎞⎠ T2
Cable
⎞
⎠
⋅⋅⋅nc Rac
Cable
⎛⎝ ++1 λ1 λ2
⎞⎠ ⎛
⎝
+T3
Cable
T4
,Cable Depth
⎞
⎠
⎞
⎟
⎟
⎟⎠
.5
1.4
1.6
1.8
2
2.2
2.4
2.6
2.8
1
1.2
3
299.5 302.5 305.5 308.5 311.5 314.5 317.5 320.5 323.5293.5 296.5 326.5
Depth
AmpD
,Cable Depth
((A))
=Iec
Cable
300 mm
2
≔θcmax ⋅(( +273.15 90)) K ≔Ambient ‥1 10 ≔θambient
Ambient
+⋅⋅5 ((Ambient)) K ⋅273 K
≔ρs ⋅90 ――
⋅K cm
W
≔L ⋅1 m =Δθ 45.15 K
≔nc 3
≔Δθ
Ambient
−θcmax θambient
Ambient
≔T4A
step
⋅――
ρs
⋅2 π
ln
⎛
⎜
⎜
⎜⎝
+――――
⋅2 L
Dinsul
step
‾‾‾‾‾‾‾‾‾‾‾‾‾‾
−―――――
(( ⋅2 L))
2
⎛
⎝
Dinsul
step
⎞
⎠
2
1
⎞
⎟
⎟
⎟⎠
≔AmpD
,Cable Ambient
⎛
⎜
⎜
⎜⎝
――――――――――――――――――――――――――――――
−Δθ
Ambient
⋅Wd
Cable
⎛
⎝
+⋅.5 T1
Cable
⋅nc ⎛
⎝
++T2
Cable
T3
Cable
T4A
Cable
⎞
⎠
⎞
⎠
++⋅Rac
Cable
T1
Cable
⎛
⎝
⋅⋅⋅nc Rac
Cable
⎛⎝ +1 λ1
⎞⎠ T2
Cable
⎞
⎠
⋅⋅⋅nc Rac
Cable
⎛⎝ ++1 λ1 λ2
⎞⎠ ⎛
⎝
+T3
Cable
T4A
Cable
⎞
⎠
⎞
⎟
⎟
⎟⎠
.5
Non-Commercial Use Only
5-ampacity-IEC-upload.mcdx

29. =Iec
Cable
0 m
2
14
18.5
23
27.5
32
36.5
41
45.5
5
9.5
50
570 595 620 645 670 695 720 745520 545 770
−θambient
Ambient
⋅273 K ((K))
AmpD
,Cable Ambient
((A))
Non-Commercial Use Only
5-ampacity-IEC-upload.mcdx

30. ≔θcmax ⋅(( +273.15 90)) K ≔θambient +⋅50 K ⋅273 K
≔Soil ‥1 17
≔ρs ⋅20 ――
⋅K cm
W ≔ρ
Soil
+⋅ρs
((Soil)) ⋅30 ――
⋅K cm
W
≔L ⋅1 m ≔λ2 0 ≔λ1 .01 ≔λ1 .2301
≔Δθ −θcmax θambient ≔T4S
Soil
⋅――
ρ
Soil
⋅2 π
ln
⎛
⎜
⎜
⎜⎝
+――――
⋅2 L
Dinsul
Soil
‾‾‾‾‾‾‾‾‾‾‾‾‾‾
−―――――
(( ⋅2 L))
2
⎛
⎝
Dinsul
Soil
⎞
⎠
2
1
⎞
⎟
⎟
⎟⎠
≔AmpS
,Cable Soil
⎛
⎜
⎜
⎜⎝
――――――――――――――――――――――――――――――
−Δθ ⋅Wd
Cable
⎛
⎝
+⋅.5 T1
Cable
⋅nc ⎛
⎝
++T2
Cable
T3
Cable
T4S
Soil
⎞
⎠
⎞
⎠
++⋅Rac
Cable
T1
Cable
⎛
⎝
⋅⋅⋅nc Rac
Cable
⎛⎝ +1 λ1
⎞⎠ T2
Cable
⎞
⎠
⋅⋅⋅nc Rac
Cable
⎛⎝ ++1 λ1 λ2
⎞⎠ ⎛
⎝
+T3
Cable
T4S
Soil
⎞
⎠
⎞
⎟
⎟
⎟⎠
.5
=Cable 16
=ρ
Soil
? ――
⋅K cm
W
1.1
1.4
1.7
2
2.3
2.6
2.9
3.2
3.5
0.5
0.8
3.8
285 315 345 375 405 435 465 495225 255 525
ρ
Soil
⎛
⎜
⎝
――
⋅s
3
K
⋅kg m
⎞
⎟
⎠
AmpS
,Cable Soil
((A))
=Iec
Cable
0 m
2
=――
2733
418
6.538
Non-Commercial Use Only
5-ampacity-IEC-upload.mcdx