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Question
How to calculate cable sizes in sq.mm. with using motor KW? 
Any formula there?
 Question Submitted By :: Suresh
I also faced this Question!!     Rank Answer Posted By  
 
  Re: How to calculate cable sizes in sq.mm. with using motor KW? Any formula there?
Answer
# 1
normally for copper cable 2.5amps 1sq mm
for alluminium cable 1.5 amps for 1sqmm
 
Is This Answer Correct ?    118 Yes 40 No
Khalander Mulla
 
  Re: How to calculate cable sizes in sq.mm. with using motor KW? Any formula there?
Answer
# 2
Normally copper has more conductivity than aluminium. So it
is actually reverse. 1.5 mmsqr for copper and 2.5 mm sqr
for alu
 
Is This Answer Correct ?    36 Yes 78 No
Hemant
 
 
 
  Re: How to calculate cable sizes in sq.mm. with using motor KW? Any formula there?
Answer
# 3
THE ABOVE SAID IS WRONG , ITS A THUMB RULE I USE TO FALLOW
1 sqmm = 5A & endangering amps withstand is 8A for alu
(sqmm * 1.87A)for cu sqmm *2
 
Is This Answer Correct ?    23 Yes 34 No
Raja
 
  Re: How to calculate cable sizes in sq.mm. with using motor KW? Any formula there?
Answer
# 4
Hameent your statment is applicable for only small cable
size ( Up to 16 sq mm ) Please reff any one catalouge
 
Is This Answer Correct ?    23 Yes 15 No
A.bala
 
  Re: How to calculate cable sizes in sq.mm. with using motor KW? Any formula there?
Answer
# 5
3pahse power is P(in KiloWatt)=I.V.PF.(root 3).....
I=1.74 x P(KW)
EXAMPLE:
so, assume 3ph 400V 15KW motor, In=1.74x15=26.1 A,
& 15KW=20HP.....so 2xIn=Breaker rating= 52.2A
...choose 63A MCB

Cable size normally 20-25% higher than breaker to avoid
cable heat/burn accident in overcurrent fault. so, 1.25xIn=
62.64A so choose 80A Cable rating of 25mm2.
 
Is This Answer Correct ?    32 Yes 21 No
Abdool
 
  Re: How to calculate cable sizes in sq.mm. with using motor KW? Any formula there?
Answer
# 6
First of all you need to verified full load current of motor,
How can you calculate:
Ex: 1 Motor - 20HP 3ph. 415V 50Hz, 80% efficiency

Cal: A= HPx746/(sqrt3xVoltxPFxefficiency)

=20x746/1.732x415x0.8x0.8

=32.43Amp.

We all know that a motor has 1.5 times starting current,

Then 32.43x1.5 = 48.65Amp

Now you can see in the current currying capacity of cable from manufacturer cable's list.

3.5 x 35 sqmm xlpe cable is sufficient for full load.
 
Is This Answer Correct ?    22 Yes 15 No
Sagir Siddiqui
 
  Re: How to calculate cable sizes in sq.mm. with using motor KW? Any formula there?
Answer
# 7
for cooper 2.5 mm for 1 amp
for aluminum 1.5 mm for 1 amp
 
Is This Answer Correct ?    5 Yes 22 No
Ibrahim
 
  Re: How to calculate cable sizes in sq.mm. with using motor KW? Any formula there?
Answer
# 8
normally for copper cable 2.5amps 1sq mm
for aluminium cable 1.5 amps for 1sq mm
That is the answer.......
 
Is This Answer Correct ?    20 Yes 4 No
Bethi Arun Reddy
 
  Re: How to calculate cable sizes in sq.mm. with using motor KW? Any formula there?
Answer
# 9
what's wrong with you guys. You dont even know how to spell
correctly. Please improve on that. Its not only about idea
but also on how you convey it. Damn!
 
Is This Answer Correct ?    3 Yes 8 No
Pedro
 
  Re: How to calculate cable sizes in sq.mm. with using motor KW? Any formula there?
Answer
# 10
We must consider numerous factors to calculate the exact
safe size of the cables for a particular load.
Please let us know whether the cable is to be laid in
ground or it will be overhead or any other way.
Secondly, you want an aluminium cable or copper cable?
Thirdly, the load is single phase or 3-phase?
Moreover, the motor is induction motor or any other type?
because we have to consider harmonics also.

For e.g for a 3-phase load of 80kw, the aluminium cable to
be laid inside the ground must be 150 sq.mm for perfectly
safe operation.
 
Is This Answer Correct ?    5 Yes 1 No
Parveen
 

 
 
 
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