Why short circuit calculation is not required in LT cable
sizing and requiredin HT cable sizing only
- 2 Answers
- 10370 Views
- Chemtex, I also Faced
- E-Mail Answers
Answer Posted / sudhanva madhukar mahamuni
Generally LT Cable size are not calculated based on Fault current basis, Due to High Fault current on LT System. For e.g. consider that 2500 kVA Transformer, %Z = 6.25%, 415 Volts at Secondary. Fault Current at Secondary system will be 55.64 kA. Now if we would have to select the Cable size based on Fault current then it would be ---
If √t
A = ----------------- Sq.mm --- For XLPE Cable Aluminum Conductor
0.094
585 sqmm, nearest standard rating of cable is 630 sqmm. Hence Commercially as well as laying point of view the same is not recommended nor as per good engineering practice.
HT Cable Sizing :
Cable sizing based on Fault current is possible In HT System, based practically and commercially point of view. Consider that 11kV system is feeding the power supply. As per IS 2026, 11kV Power system will have max 500MVA Fault Level. It means it will have 26 kA. 300sqmm cable will be sufficient to withstand 26 kA for 1 Sec.
Summary : System Design shall not be strictly as norms, it should be design considering Laying / installation, Practically and Commercially viable.
Regards
Sudhanva Madhukar Mahamuni
electricmahamuni@gmail.com
| Is This Answer Correct ? | 2 Yes | 1 No |
Post New Answer View All Answers
Define super node?
Bimetal strip used in overload relay what is that,which types of material used for that & percentage.
Thumb rule of cable size(rm>30 rm)X multiplying factor=ampere
how define the torque in ac drive. from electrical side in the drive friquency ,voltage and current three factor is there.
I need bhel previous year quetion papers for electrical engineering department.I searched but i could not find out
Why does inductive loads consume KVARs?
How many sprinklers should be in one pipe line?
Why GRR starts from 60% of motor speed why not less than 60%?
why the colour of insultor stack , petticoat is brown. Is it has some technical reason.
What is corkscrew rule?
HOW TO CALCULATE AMPs OF CURRENT TRANSFORMER IN HT Panel
What is the function of Governor in Hydro Power Station? What is the Function of Lightning Arrestor Voltage Transformer (LAVT)?
what is metering cum synchronizing panel and how it is used?
How many kinds of E.L.C.B and how to work E.L.C.B
Please, if 1kw is equal to 1.25kva; how then do I know how many kva in 7.5kw?
