Answer / khalander mulla

normally for copper cable 2.5amps 1sq mm
for alluminium cable 1.5 amps for 1sqmm

Answer / sagir siddiqui

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.

Answer / bethi arun reddy

normally for copper cable 2.5amps 1sq mm
for aluminium cable 1.5 amps for 1sq mm
That is the answer.......

Answer / abdool

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.

Answer / parveen

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.

Answer / sharma

kw to cable size

Answer / a.bala

Hameent your statment is applicable for only small cable
size ( Up to 16 sq mm ) Please reff any one catalouge

Answer / rana farrukh anwsr

First of all we will chk rated amp mentioned on motor then will check from chart abt cable sq mom size

Answer / ramkashyap

For Cable Current Capacity = 4X Size of Cable in Sq.mm, Ex. For 2.5 Sq.mm = 4×2.5 = 9 Amp.

Answer / s d chilatre

required copper wire in kg for rewinding Ind. motor for various rating

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