How the cable size for a motor is decided

Answers were Sorted based on User's Feedback

How the cable size for a motor is decided..

Answer / govind

Thae cable size of the motor is decided from the rated load
(in Amps)of motor.

Is This Answer Correct ?    78 Yes 9 No

How the cable size for a motor is decided..

Answer / shantanu dash

The cable size of a motor mainly depends on the following

(i) Rated Current of Motor
(ii) Starting current and starting time of the Motor on
(iii) Type of starters used for starting the Motor

Is This Answer Correct ?    69 Yes 1 No

How the cable size for a motor is decided..

Answer / bhupatsinh

its depends on motor max. current, votage, and lenght of
cable.and volatage drop.

Is This Answer Correct ?    29 Yes 1 No

How the cable size for a motor is decided..

Answer / arvind

The cable size of motor depend on rated current of motor,
but as the motor draw more current at starting which will
be around 2-3times the rated current, so cable size will
going to be increased i.e, wherever we will calculate we
take 20% extra for selection of your cable

Is This Answer Correct ?    25 Yes 6 No

How the cable size for a motor is decided..

Answer / sanjeev pal

motor cable is decided according to motor rated current
given in specification plate. WHEN MOTOR is initially
running condition then motor draw current 1.5 times more its
rated current. so this factor decided cable size of motor

example 10 HP MOTOR rated current is 14.7 or 15 ampere
when initial running condition draw 1.5 times more
14.7 * 1.5 = 22.05 ampere then current caring capacity
of cable is 22 Ampere must be necessary.

correct answer hai

Is This Answer Correct ?    24 Yes 11 No

How the cable size for a motor is decided..

Answer / imran khan

Cable size of motor is decided on the following factors:
1. Full load current of motor(Since P=VICoso/Sqrt3VICoso)
2. Length of Cable.
3. Method of cable laying.(Air(Tray)/Underground(duct)).
4. Voltage drop of cable.

Calculation will be as:
1. If cable is laid on Tray/underground take its
corrosponding derating factors.
2. Multiply all derating factors & this derating factor is
multiplied by current carrying capacity of the cable which
you are going to sellect(from catalogue).
3. Above current should not be less than full load current
of motor.
4. Then check voltage drop (Vd=(IxLxmV/A/m)/(Rx1000))
where Vd=Voltage drop, I=Current(full load),L=length of
Cable(site requirement),mV/A/m=millivolt/Ampere/meter(from
catalogue),R=No. of Runs of cable.
5. Above voltage drop should not be more than 4%/2.5%(As
per requirement).

Is This Answer Correct ?    6 Yes 0 No

How the cable size for a motor is decided..

Answer / mithilesh

in Most of above answer every one stating about staring
current, current rating of motor but only one guy stated
about voltage drop of cable.

i think guy who stated about voltage drop,current rating,
power rating of motor( because starting current varies
with Hp rating of motor lower the hp higher the staring
current) his answer is more regionable than others.

from my experince i would say only full load current rating
of motor & voltage drop of motor will be enough to
calculate the cable size because staring current is only
for less time. and all cable has been designed for 2-3
times of rated current for 1 min. this answer will be
perfect for higher rated motor( more than 50hp)

less than 50 hp motor we have take consideration of
sttarting current( because starting current 3-4 times of
full load current).

Is This Answer Correct ?    7 Yes 2 No

How the cable size for a motor is decided..

Answer / md gufran yaqub

cable size for motor is decided based on
-rated load
-starting method and current withdrawn generally conductor
size is selected 2-3 times that of rated load
-length of cable and duty type decides the cable insulation
-obviously the cable rating should not be less than
protecting device

Is This Answer Correct ?    6 Yes 3 No

How the cable size for a motor is decided..

Answer / praful nandankar

To limit the starting current there are various protection
devices. Manufacturers always design the motor cable taken
into consideration the after effects of starting current.It
depends on the motor rated current and the voltage drop
which is already mentioned in some answers.

Is This Answer Correct ?    2 Yes 1 No

How the cable size for a motor is decided..

Answer / dilanka

motor drowse starting current which will be around 2-3 times
the rated current. so cable size going to be increase.How
ever it is suitable to select 125% or 130% current rate for
cable because the cable can withstand without any damage for
few second. you must check the cable manufacturing data to
find this specific time and it should be more than the
starting time period of the motor.

Is This Answer Correct ?    0 Yes 0 No

Post New Answer

More Electrical Engineering Interview Questions

What is the method for testing the differential protection stabilty in generator? When the time of starting What will happen if differentail protection connection wrong means?

0 Answers   JSW,

In case of salient pole alternator when number of poles are 4 or more than 4 it helps the flux wave to be sinusoid as air gap length is increased from center to tip , but if the number of poles are 2 how does the flux wave is sinusoidal?

0 Answers  

what is the id1 & id2 setting in differential protection relay of CSPC?

0 Answers   Wartsila,

in the exciter the power is feeded from battry or control or whatever.and we need it in the generators for the stating . do we need it in the shutdown also?i mean the exciter>

2 Answers   Shell,

why the field winding of synchronous machine is excited by dc source

2 Answers  

why scott connection is done why not two phases are directly picked at the output of 3 phase transformer??

1 Answers  

Why electrical heaters are not provided with overload relays in circuits

1 Answers  

What is mean by hormonics?

5 Answers  

what is meant by transformer differential protection ?

3 Answers   BFL,

What happens if 25 Hz frequency is applied for 400/200,50 Hz single phase Transformer.Will Voltage increase ?

2 Answers   IBM, Bhel, Dawlance,

In hydel power plants, L.A's, S.C's are placed inside the control panel boards. what is the purpose? [already the total body was earthed to ground.]

0 Answers  

what is AVP?

2 Answers  

  • Civil Engineering Interview Questions Civil Engineering (5038)
  • Mechanical Engineering Interview Questions Mechanical Engineering (4248)
  • Electrical Engineering Interview Questions Electrical Engineering (16422)
  • Electronics Communications Interview Questions Electronics Communications (3525)
  • Chemical Engineering Interview Questions Chemical Engineering (959)
  • Aeronautical Engineering Interview Questions Aeronautical Engineering (192)
  • Bio Engineering Interview Questions Bio Engineering (95)
  • Metallurgy Interview Questions Metallurgy (360)
  • Industrial Engineering Interview Questions Industrial Engineering (253)
  • Instrumentation Interview Questions Instrumentation (2962)
  • Automobile Engineering Interview Questions Automobile Engineering (328)
  • Mechatronics Engineering Interview Questions Mechatronics Engineering (90)
  • Marine Engineering Interview Questions Marine Engineering (107)
  • Power Plant Engineering Interview Questions Power Plant Engineering (170)
  • Textile Engineering Interview Questions Textile Engineering (198)
  • Production Engineering Interview Questions Production Engineering (0)
  • Satellite Systems Engineering Interview Questions Satellite Systems Engineering (89)
  • Engineering AllOther Interview Questions Engineering AllOther (1375)