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Question
`how to choose the cable rating for load (KW)? EXAMPLE.50KW load`
I also faced this Question!!     Rank Answer Posted By

Re: how to choose the cable rating for load (KW)? EXAMPLE.50KW load
# 1
Copper Cable: Sqmm*1.5, Exam: If we have 50 Sqmm copper
cabe, The it will take load is 50*1.5=75Amp

Al Cable is multiplying factor of 1.
Exam: 50 Sqmm cable will take 50A load.

 Is This Answer Correct ? 78 Yes 202 No
Suresh Kumar

Re: how to choose the cable rating for load (KW)? EXAMPLE.50KW load
# 2
In a three phase system p=1.732x3xVxIxCOS@
Then I=50000/1.732x3x415x.8
taking some future expectancy you can take a cable of
having 100A capacity.SO by this u can take a cable of 70mm
square in aluminium and 50 mm square in copper

 Is This Answer Correct ? 93 Yes 60 No
Vinod Sharma

Re: how to choose the cable rating for load (KW)? EXAMPLE.50KW load
# 3
Cable carring capasity is there.. we can get form cable
manufacturer...

current(I) = 50/(1.732*415*.8(p.f))
I = 28.75A
For 1.5Sqmm cable curent carring capasity = 20A in ground
2.5 = 27,
4 = 34,
6 = 43,
10 = 57,
16 = 73A like that.
now our load current is 28.75A
No.of cable with size =28.75/43A (6Sqmm)
= .6686/.7 (Diff factor)
=.955
there fore 1run 6 Sqmm aluminium cable we selected for 50

 Is This Answer Correct ? 26 Yes 129 No
Parasuram

Re: how to choose the cable rating for load (KW)? EXAMPLE.50KW load
# 4
Right cable size Sellection depends on 3 factors:
1- Load Current.current(I) = 50kW /(1.732*415*0.85
(p.f)) =139A

3- Allawable Voltage droop in your system (Should be less
than 5% )

As experience you can use 10sqrmm for 40A,for 120meter.

 Is This Answer Correct ? 44 Yes 25 No
Engineer

Re: how to choose the cable rating for load (KW)? EXAMPLE.50KW load
# 5
Fisrt calcultate Load in Ampere as basic formula below

I (Amp ) = P ( KW) / 1.732*Voltage (400 or 415 or 380 )*
p.f

Voltage depend on frequency rating (50 Hz or 60 Hz)
then check where you have to laid in AIR or Ground
you have to consider so many factor.
suppose you laid in Ground then factor to be consider as
below
(1) Soil Thermal Rseistivity
(2) Group factor
(3)Rating factor of ground temprature
(4)Rating Factor depth of laying

then calculte Voltage drop on behalf of amper rating by
once you calculate then check length

V.D = mv x I X L/1000 OR mv =V.D X 1000/IXL

VD= Maximum acceptable volt drop (in volt)
mv =appropriate volt drop (in mv /amp /metre
I = Current per phase (in ampere)
L= Length ( in meter)

 Is This Answer Correct ? 26 Yes 6 No

Re: how to choose the cable rating for load (KW)? EXAMPLE.50KW load
# 6
I = p/((root3)*V*P.F )
where I line current, v line voltage
then go to cable tabe
and check the Drateing factors.such as
if this cable underground,free,soil,depth of laying,
ambient temperture, armoed or unarmoed etc.

then calcute the voltage drop
if more than 4%
you should to select the next bigger cross section at table.

by experince for copper PVC cables
1mm take 2.5 AMP

 Is This Answer Correct ? 13 Yes 6 No

Re: how to choose the cable rating for load (KW)? EXAMPLE.50KW load
# 7
1 H.P = 1.25 Amps
IN CASE ALUMINIUM CONDUCTOR USE CONSTANT VALUE IS =0.75
IN CASE COPPER CONDUCTOR USE CONSTANT VALUE IS =1.25

SO CONDUCTOR SIZE= 1.25*1.25(CU)=1.25SQMM

 Is This Answer Correct ? 14 Yes 23 No
Er.p.somasundaram

Re: how to choose the cable rating for load (KW)? EXAMPLE.50KW load
# 8
10 H.P = 10.25 Amps
IN CASE ALUMINIUM CONDUCTOR USE CONSTANT VALUE IS =0.75
IN CASE COPPER CONDUCTOR USE CONSTANT VALUE IS =1.25

SO CONDUCTOR SIZE+cable sqmm *075 =10.25amps, now a days increase current so cable size is small size increases.
10.25*0.75=10 sq mm

 Is This Answer Correct ? 10 Yes 19 No
Er.p.somasundaram

Re: how to choose the cable rating for load (KW)? EXAMPLE.50KW load
# 9
50kw load will take 87 amps (approx.). There is table of
different types of cables available in the manufactures
site. More over there is so many factors are there to
select a cable. Such as the type of material (copper /
aluminium), single core or multicore, how and where the
cable is being laid, the length of cable(for voltage drop
calculation), type of load and its starting current (for
70sq.mm Aluminium cable or 50sq.mm copper cable can be used.

 Is This Answer Correct ? 10 Yes 10 No
Shabeeb

Re: how to choose the cable rating for load (KW)? EXAMPLE.50KW load
# 10
LOAD : 50kW , 415V , 0.8p.f
1- I = 28.75A
2- 28.75 * 1.2 = 34.5A
3- temp. factor * group factor = 0.75 "ex."
4- 34.5/.75 = 46A
5- choose 16mmsq
6- cal. Vd = (I * L(m) * delta(v)/ (V * 1000))*100%
its should less than 5%
7- short circuit temp. rise

 Is This Answer Correct ? 7 Yes 11 No
Mathhar

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