Follow Our FB Page << CircleMedia.in >> for Daily Laughter. We Post Funny, Viral, Comedy Videos, Memes, Vines...


how can we know cable size for a given current?
if any one have catalogue plz mail to
vijay_raju369@yahoo.co.in

Answers were Sorted based on User's Feedback



how can we know cable size for a given current? if any one have catalogue plz mail to vijay_raju3..

Answer / m.faisal siddiqui.

The selection of a cable size for a given value of current
can be done using the cables & tables provided by the cable
manufacturer. The selection of cable size also depends upon
the lenght of cable from source to load. The total voltage
drop should not exceed 2.5% of rated voltage. Following
factors shall be considered while selecting a cable for
required load.

1. Rated Current.
2. Capacity of Protective Circuit Breaker used.
3. Total Length of cable.
4. Total voltage drop.
5. Laying Method.i.e. underground,in conduit,in trays etc.
6 No. of cables.i.e. grouping factor.
7. Ambient Temperature of installed area.
Temperature Correction Factor to be applied.
8. Type of cable. i.e. singel core,multicore,PVC insulated,
Armoured, XLPE insulated etc.

Is This Answer Correct ?    25 Yes 2 No

how can we know cable size for a given current? if any one have catalogue plz mail to vijay_raju3..

Answer / shrikant muthineni

For an aluminium conductor we can load approximately 2.5
amperes and for a copper conductor aroundf 6 amps

Is This Answer Correct ?    20 Yes 7 No

how can we know cable size for a given current? if any one have catalogue plz mail to vijay_raju3..

Answer / vasu

Two things are very much common on the power system engineering field while doing a cable sizing, these are:
1)LT
2)HT

Cables are separately sized based on voltage levels as said above.

Formulas used for LT side:

Full load current = KW/(KV x sqrt3 x PF x &#951;)

Voltage Drop =
sqrt 3*IFL*(R COS Ø + X SIN Ø)*L/(KV*10000*N.R.)

where

IFL = Full load current of the Load connected in Amps
KW = Rating of the Load connected
KV = System Voltage
R = Resistance of the cable in Ohm/Ph/KM
X = Reactance of the cable in Ohm/Ph/KM
L = Length of the cable in meters
N.R = No of Runs of the cable
cosØ = Power factor of the system
PF = Power factor
&#951; =efficiency


Voltage Drop =
sqrt 3*Ist*(R COS Ø + X SIN Ø)*L/(KV*10000*N.R.)

where Ist=starting current which can be 6 times the FLA of current.In technical term it is called as LRC(locked rotor current)


HT side:

Full load current = KVA / KV x sqrt 3

Short circuit current :
A = Ish x sqrt(t)/ k


Where
t = short circuit time in sec
k = constant
A = Conductor size in Sqmm
Ish = Short circuit current in Amps
Derating Factor :

Ambient temperature correction factor for cables laid in 0.9 Trays at 50 degree C = 0.9

Group derating factor:

Multi Core cables
Cables are laid with a spacing of one Diameter and routed in cable trays and trays in tiers by 300mm =0.9
Ageing factor= 0.95
Therefore the Total derating factor = 0.9 x 0.9 x 0.95 = 0.7695
Total Derating Factor= 0.77



The rest calculation for voltage drop are same as that of LT side

Is This Answer Correct ?    8 Yes 3 No

how can we know cable size for a given current? if any one have catalogue plz mail to vijay_raju3..

Answer / bijumone.g

roughly you can take it as 1.5 times of the conductor
size.eg. 300 sqmm can conduct 450 A approximately and
moreover it also depends on the application like
underground or overhead.

if you want in detail you can check it in finolex website.

Is This Answer Correct ?    12 Yes 9 No

how can we know cable size for a given current? if any one have catalogue plz mail to vijay_raju3..

Answer / manoj sharma

Thank U very much VASU

Is This Answer Correct ?    6 Yes 3 No

Post New Answer



More Electrical Engineering Interview Questions

if we give DC suply to the AC motor what hapen

5 Answers   TATA,


Why we apply only reduced voltage to the alternator while conducting slip test ? also the current increases to a larger value with reduced voltage itself Why ?

1 Answers  


Hai, I am from EEE branch.On feb 17 iam going to write an Exam for hindustan petrolium corporation Ltd.So plz send me the written exam pattern/Q's/interview questions.please mail to yuva_polisetti@yahoo.co.in

0 Answers  


What is the significance of %Z in case of transformer?

1 Answers  


1) name the communication cable and how it is communicate in between plc to modbus , plc with hmi? 2)name of the communication cables?

1 Answers  






how the synchronizing is obtained at bus couplers in grid substation? (because there we cannot change the frequency in one of transmission lines like in generator synchronization)

0 Answers  


if 300 hrs not comleted at wat interval b.c,d checks og take place

1 Answers  


explain working of differential protection for a transformer?

1 Answers   BARC,


WHAT IS A COLOUR CODING OF 3 CORE CABLE

11 Answers  


Hydro P.P. run @ 600 rpm,8pole, Nucler P.P @ 1500rpm 4 pole , ThermlP.P @ 3000 rpm 2 pole.Why this diffrence??? when we can generate electricity @ 600 rpm then Why we had incresed speed in NPP & TPP???

3 Answers  


How to calculate the average power factor in 3 phase unbalanced system

5 Answers   Bhel, MacLellan,


why the power cut problems occur in tamil nadu? may i know the exact reason.plz

17 Answers  






Categories
  • Civil Engineering Interview Questions Civil Engineering (5074)
  • Mechanical Engineering Interview Questions Mechanical Engineering (4444)
  • Electrical Engineering Interview Questions Electrical Engineering (16594)
  • Electronics Communications Interview Questions Electronics Communications (3915)
  • Chemical Engineering Interview Questions Chemical Engineering (1092)
  • Aeronautical Engineering Interview Questions Aeronautical Engineering (214)
  • Bio Engineering Interview Questions Bio Engineering (96)
  • Metallurgy Interview Questions Metallurgy (361)
  • Industrial Engineering Interview Questions Industrial Engineering (258)
  • Instrumentation Interview Questions Instrumentation (2987)
  • Automobile Engineering Interview Questions Automobile Engineering (332)
  • Mechatronics Engineering Interview Questions Mechatronics Engineering (97)
  • Marine Engineering Interview Questions Marine Engineering (122)
  • Power Plant Engineering Interview Questions Power Plant Engineering (170)
  • Textile Engineering Interview Questions Textile Engineering (575)
  • Production Engineering Interview Questions Production Engineering (0)
  • Satellite Systems Engineering Interview Questions Satellite Systems Engineering (106)
  • Engineering AllOther Interview Questions Engineering AllOther (1377)