cable selection

hi friend

Your question is very general with out much of details.

The electrical cables are mainly categorised as Power cable, control cable,telecommunication cable and special purpose cable .

Power Cable selection will depend on the voltage, type of cable, laying conditions,de rating factors and many other considerations as mentioned briefly but needs elaborate study.

1. Short circuit rating of cable

It will depend on its size ,insulation,initial temperature,finial permissible rise of temperature of the cable ( The data will normally be provided by the cable manufacturer)It will also depend on the type of cable PILC/PVC/ XLPE , Earthed or un earthed system etc. Duration of short circuit depending on the protective system and back up protection which are other important point to be considered.

2.. Voltage drop

You must check the likely voltage drop for which standard chart is available which should be referred.

3. Power loss.

The power transmission loss in cable should be calculated as per the data provided by the the cable manufacturer.

4. Type of cable laying / depth of cable laying soil conditions etc. and other de rating factors to be considered for the calculation

Sunil,

Cable sizing for simple electrical loads (such as 1 motor) is determined based on the amount of current (Amperage) that a conductor of a certain size is rated for. Here is a link to table that gives Conductor Requirements for ISO 10133 and ISO 13297.

http://www.energy-solutions.co.uk/cable_conductor.html

For more complex electrical loads - multiple motors or circuits - you need a certified electrician or an electrical engineer to do it for you.

Mate it is real easy. Cable manufacturers produce books which list all the cables they manufacture with colmns for current carrying capacity, voltage drop, derating factor etc. Try Pirelli cables or Olex if you want metric ratings and Amercable if you want Imperial.