(phi)1
(phi)c
=
=
=
=
=
kVAr 2
The load is running at iniatial power factor
Required to be corrected power factor
kilovolt amperes reactant
Total connected load
After diversity maximum demand
= TCL x [tan (phi)1 - tan (phi)c]
= 50.00
=
= 0
= 0.80
kiloWatt
kVA
Short Cicuirt Current Calculation
Formula:
kxS
t
Where:
= Short circuit current (Amps)
I
= Copper area of conductor (mm)
S
= Duration of short circuit current (seconds)
t
up to 5 seconds maximum
= Constant to allow for an initial temperature
k
of 90 C & final conductor temperature of 250 C
= 143
90.0
1
= 12,870.00 Amps
Notes:
1
The formula given is based on the cables being fullly loaded at the start of a short
circuit (conductor temperature 90 C) and a final conductor temperature of 250 C.
It shound be ensured that the accessories associated with the cables are also
capable of operation at these values of fault current and temperature.
Voltage Drop Calculation:
Data:
total connected load:
50.00
440
3
60
295
90%
Operating Voltage:
Phase:
Frequency:
Total Distance:
Power Factor:
KiloWatt
Volts
Hz
Feet
8,997.70
90.00
cm
meter
I full load = (KW x 1,000)/^0.5xVxPF)
I full load
Proposed Wire Size:
V drop = ((2xK) x L x Ifull load)/ d
72.90
90.0
87%
Amps
mm
Where:
K = Resistance of conductor per foot
12 for circuits loaded more than 50% of conductor
12
11
18
current carrying capacity
11 for circuit loaded not more than 50% of conductor
current carrying capacity
18 for aluminum conductors
L = length of conductor,(feet)
I = Full Load current
d = cross-section of conductor in Circular - Mill
0.0005067 mm per Cir-Mil
V drop
% V drop
177619.8934 CM
2.31889387 volts
0.47%
Notes:
1. Voltage Drop shall not exceed 3% of operating voltage
2. Increase of conductor as necessary to limit voltage drop to < 3%
0.0005067
Table 4.8 Current rating of mineral insulated cables clipped
directVolt drops for mineral insulated cables
Table 4.9 Volt drops for mineral insulated cabl
(from [Tables 4G1B &4G2B] of BS 7671:2008)
(from [Tables 4G1B & 4G2A] of BS 7671:2008
Cross-sec
p.v.c sheath
p.v.c sheath
p.v.c sheath
area
2xsingle/twin
3 core
3 x single
(A)
(A)
(A)
(A)
(A)
(mm)
bare sheath
bare sheath
2xsingle/twin 2xsingle/twin
Cross-sec
Single-phase Single-phase
area
p.v.c sheath
bare
(mm)
(mV/A/m)
(mV/A/m)
1.0
(500V)
18.5
15.0
17.0
22.0
21.0
1.0
42.0
47.0
1.5
(500V)
23.0
19.0
21.0
28.0
27.0
1.5
28.0
31.0
2.5
(500V)
31.0
26.0
29.0
38.0
36.0
2.5
17.0
19.0
4.0
(500V)
40.0
35.0
38.0
51.0
47.0
4.0
10.0
12.0
1.0
(750V)
19.5
16.0
18.0
24.0
24.0
6.0
7.0
7.8
1.5
(750V)
25.0
21.0
23.0
31.0
30.0
10.0
4.2
4.7
2.5
(750V)
34.0
28.0
31.0
42.0
41.0
16.0
2.6
3.0
4.0
(750V)
45.0
37.0
41.0
55.0
53.0
6.0
(750V)
57.0
48.0
52.0
70.0
67.0
10.0
(750V)
77.0
65.0
70.0
96.0
91.0
16.0
(750V)
102.0
86.0
92.0
127.0
119.0
Formula:
VDrop
(mV/A/m(for selected cable))(
1000
for mineral insulated cables
4G1B &4G2B] of BS 7671:2008)
Three-phase Three-phase
p.v.c sheath
bare
(mV/A/m)
(mV/A/m)
36.0
40.0
24.0
27.0
14.0
16.0
9.1
10.0
6.0
6.8
3.6
4.1
2.3
2.6
(mV/A/m(for selected cable))(IF)(L)
1000
Approximate Diameter
Approximate
Cable weight
Conductor Area
Under Armour
mm
mm
1.5 *
2.5 *
4*
6*
10 *
16 *
25
35
50
70
95
120
150
185
240
300
400
9.1
10.6
11.4
13
15
18
20
22.8
25.5
29.5
33.5
37.5
41.5
46
52.5
57.5
65
Armour wire Dia
Overall
mm
mm
kg / km
600 / 1000 V Copper Power Cables
0.9
13.5
380
0.9
14.5
445
0.9
17
550
1.25
18.5
770
1.25
20.5
1020
1.25
23.5
1320
1.6
26.1
1840
1.6
28.6
2310
1.6
32
2970
2
37.7
4240
2
41.7
5400
2.5
47.1
7000
2.5
51.4
8350
2.5
56.6
10130
2.5
63
12840
2.5
68.8
15530
3.15
78.1
19950
Maximum armour
resistance at 20
C
Maximum
conductor
resistance at 20
C
Ohm / km
Ohm / km
8.8
7.7
6.8
4.3
3.7
3.1
2.3
2
1.8
1.2
1.1
0.76
0.68
0.61
0.54
0.49
0.35
12.1
7.41
4.61
3.08
1.83
1.15
0.727
0.524
0.387
0.268
0.193
0.153
0.124
0.0991
0.0754
0.0601
0.047
Free Air (method 13)
CURRENT
RATING
Volt Drop Per
Amp per Metre
Amp
mV
Three Phase a.c.
25
27
33
16
44
10
56
6.8
78
4
99
2.5
131
1.65
162
1.15
197
0.87
251
0.6
304
0.45
353
0.37
406
0.3
463
0.26
546
0.21
628
0.185
728
0.165
Enclosed in conduit (method 30)
Nominal
Conductor Area
Radial Thickness
of Insuation
Mean Overall
Diameter (upper
limit)
Approximate
Cable Weight
Maximum
conductor
Resistance at
20C
mm
mm
mm
kg/km
ohm/km
amp
mV/A/m
amp
mV/A/m
1.5
2.5
4
6
10
16
25
35
50
70
95
120
150
185
240
300
400
500
630
0.7
0.8
0.8
0.8
1
1
1.2
1.2
1.4
1.4
1.6
1.6
1.8
2
2.2
2.4
2.6
2.8
2.8
3.4
4.1
4.7
5.4
7
8
10.1
11.3
13
15
17
19
21
23.5
26.5
29.5
34.3
38.2
42.5
22
33
49
69
116
175
274
367
495
699
968
1164
1413
1828
2320
2988
3700
4750
6000
12.1
7.41
4.61
3.08
1.83
1.15
0.727
0.524
0.387
0.268
0.193
0.153
0.124
0.0991
0.0754
0.0601
0.047
0.0366
0.0283
22
30
40
51
71
95
126
156
189
240
290
336
375
426
500
573
683
783
900
31
19
12
7.9
4.7
2.9
1.9
1.35
1.05
0.75
0.58
0.48
0.43
0.37
0.33
0.31
0.29
0.28
0.27
19
26
35
45
63
85
111
138
168
214
259
299
328
370
433
493
584
666
764
27
16
10
6.8
4
2.5
1.65
1.15
0.9
0.65
0.5
0.42
0.37
0.32
0.29
0.27
0.25
0.24
0.23
Three or Four
Two cables,
Three or Four
Two cables,
cables, Three
Single phase a.c.
Cables, Three
Single phase a.c.
phase a.c. Volt
Volt Drop per
Phase a.c Current
Current Rating
Drop per Amp per
Amp per Metre
Rating
Metre
Single - core PVC insulated, non armoured, stranded copper conductors
( BS 6004 & BS 6346 )
Size of cables, in 'concealed' conduits
Max. rating of'
2 x 1C, 1 Phase
3/4 x 1C, 3 Phase
MCB / MCCB
mm
mm
(A)
1.5
1.5
10
2.5
2.5
15
4
4
20
6
6
25
6
10
30
10
16
40
16
25
50
25
35
60
35
50
80
70
100
95
125
120
150
Max. Load
current / demand
(A)
10
15
20
25
30
40
50
60
80
100
125
150
Edition 16 IEE wiring regulation
Current demand calculation
where:
P
V
P.F
=
=
=
1500 kw
440 volt
90%
2186.9
amp
Fault Current Calculation
where:
I
t
k
= 2186.9 amp
=
0.2 sec
= 143
100
100
25
25
%
%
%
%
6.8
mm
Applying diversity:
1st unit
2nd unit
3rd unit
4th unit
Total assumed Current demand
=
=
=
=
0
0
0
0
0 amp
Loop Impedance calculation (Zs)
where:
Zs
Loop impedance
Ze
External loop Impedance for distributor &services cables
R1
Resistance of the phase conductor
R2
Circuit protective conductor (Earth)
Zs
Ze + ( R1 + R2)
( R1 + R2)
Tabulated value of(R1+R2) xCircuit Length x Multiplier
1000
Correction Factors
where:
Ca = Factor for ambient temperature
Cg = Factor for groups of cables
Cf = Factor if BS 3036 rewirable fuse is used (factor is 0.725)
Ci
= Factor if cable is sorrounded by thermally insulating material
Ib
= Design current
It
= Tabulated conductor current carrying capacity
In
= Nominal rating or setting of protection
Iz
= Current carrying capacity of the conductors
I2
= Current causing operation of the device
It
In
Ca x Cg x Cf x Ci
Short Circuit Current Calculation
Formula:
kxS
t
Where:
= Short circuit current (Amps)
I
= Copper area of conductor (mm)
S
= Duration of short circuit current (seconds)
t
up to 5 seconds maximum
= Constant to allow for an initial temperature
k
of 90 C & final conductor temperature of 250 C
= 143
303.35
1.5
0.5
Amps
Notes:
1
The formula given is based on the cables being fullly loaded at the start of a short circuit
(conductor temperature 90 C) and a final conductor temperature of 250 C.
It shound be ensured that the accessories associated with the cables are also capable of
operation at these values of fault current and temperature.
Power Factor improvement
at 90% power
at 60% power
factor
factor
1273.5 kvar
1350 kvar
76.5 kvar
1500 kvar
