How to Select the Size of HT Cable

3 Major points are

1. Sckt current suitability

2. Voltage drop.

3. Derating due to installation and ambient

Other points are

1. Voltage level

2. Insulation

3. Application

4. Temperature rise

How to calculate the shor ckt. current of plant if we dont know the Fault level of sub-station. Is there any alternative method

If you are a 3rd year student in college you will learn calculation of fault current. Draw equivalent impedance diagram of the circuit and find the fault current at a point.

I will suggest you to go through text book.

The HT cable size will depend upon the short ckt.level.The supply authority gives the MVA level and u have to find the S.C. cuurent and this S.C current is divided by the "K" K= constant value of the conductive material. and then u can follow the HT cable catalog to choose HT cable according to Fault Level. Thanks Asif Iqbal

by using this formula you can find the short circuit

short circuit current=0.143*size of the cable/(t)2i

Is there any thumb rule formula