Interested to Buy Any Domain ? << Click Here >> for more details...
What is the formula to find out cross sectional area of
cable for certain current rating?
- 1 Answers
- 7674 Views
- MRF, I also Faced
- E-Mail Answers
Answer Posted / tarun aggarwal ymca
what u have to first take into mind what type of cable u want to purchase....then its size matter
usually we use XLPE insulated cable for Power cable and Aluminum or copper its depend upon the cost and loses
mean if u need large length cable you have to prefer aluminum in shorter length copper cable is preferred as its resistivity is less
for example
VLL = 11kV (line volatge)
L = 1.3km
Maximum allowable Vdrop = 2.5% of VLL i.e.Vdrop = 275V
SkVA = 3000kVA (Total Power we have to transfer of to be used by the connected load)
Full load Current If= SkVA/root3 VLL i.e If = 157.5A
Demand factor is what we actually demand the current (it not always full load current what we demand) Let D.F = 80% of If
Id =D.F x If (Demand Current) where D.F = Demand Factor i.e Id = 126.0A
The cable current carrying capacity is always kept larger than the demand current let S.F for Cable in % = 30% Extra Id
Ic= (1+S.F/100) Id i.e Ic = 163.8A
This current is what will be safer current that will be carried out by cable
Now derating factor K is calculated by the following equation
K = Kground x Ktherm.res x Kdepth x Kgroup
Vdrop = 3IdL root(Rac cos􀄳+ Xsin􀄳)
Now cable data is refered
Type 3 Core, Copper Conductor, XLPE insulated, Copper tape Screened, PVC bedded, Steel Wire Armoured, PVC, 8750/15000V.
Parameter -------- 50 mm2---- 70 mm2 ------ 95 mm2------- 120 mm2 ------- 150 mm2 ----- 185 mm2
Irated (A) --------- 187----------- 227- ------------ 267--------------303 -----------------338------------------ 383
Kground----------------0.86
Ktherm.res-- ----------- 1
Kdepth-------------------0.98
Kgroup ------------------0.7
K-------------------------- 0.590
Icor (A) -----------110.32 --------- 133.92----------157.52--------- 178.76-------------199.41------------225…
Rac (ohm/km) --- 0.493 --------0.342------------ 0.247------------0.196---------------0.1… ------------ 0.128
X (ohm/km) --------0.118 --------0.112 ------------0.106------------0.102------…
P.F = Cos--------0.85
(In radian)-------- 0.5548------ 0.5548----------0.5548-----------0.5548-…
Vdrop (V)-----------196.76-------167.73-------…
Considering the values of Ic, Icorrected and Vdrop the best suited cable is 120 mm2
cable for connecting switchyard to substation
Sorry extra long answer but i want to explain in detail
| Is This Answer Correct ? | 7 Yes | 2 No |
Post New Answer View All Answers
A TRANSFORMER 440/400V,DELTA/STAR CONNECTED.THE NEUTRAL CONNECTED WITH GROUND CABLE THAT IS DIRECTLY CONNECTED TO THE PANEL,FROM PANEL IT IS CONNECTED EARTH PIT.IS IT RIGHT? IF IT IS RIGHT LEAKAGE CURRENT AFFECTED.SECONDATY IS PROTECTED WITH EARTH LEAKAGE RELAY.
Dg pf .71 i am improve pf 0.80 what capacitor connected in dg how?
What are capacitive,resistive,inductive surge absorbation? What is ferranti surge absorber? What is lagrangian cost? What is Px operator?
Where burned of electricity,when,who, & why.
what is the responsibility of C license holder in industry?
why we need to us lenz's law for synchornous motor
Does all the output contacts (N/O as well as N/C) of a Numerical relay operate when relay receives a binary input/inputs or contacts are designated to specific logic input/inputs and only these contacts operate?
what is the acceptable limit value for Desolve Gas Analysis/
How capacitor improves pf
What will be the size of copper cable (each for 3 phase and 1 neutral) from Service connection Kit-Kat to Panel Board (i.e. to main switch) for a 6 pole 3-phase AC induction motor of 200 H.P. capacity? Amp-255 A, Frequency:- 1450 rpm.
How to design a Unit auxiliary transformer for a power house having a unit of 65 MW and Generating voltage of 11 KV and Secondary voltage of 433V
what is the role of energy meter in distribution system ?
Why does an induction generator is preffered as compared to synchronous generator in especially a wind energy power production project?
What is relation between mu(nought) and epsilon(nought)?
What is an iron loss or core loss pi?
