Cables

• Conductors : 

 It's is a material usually a metal in which the electron are closely borned to the central nucleus. This electrons become free electron which allow heat and electricity to pass easily to it.

• Insulator :

 It's is a non-metal in which the electron are firmly bounded to the neclus therefore it will not allow heat or electricity to not passing through it.

• Core : 

  Core is a circular conductor with a cable is known as core.

- Conductor are of Copper, Aluminium, Gold, Silver etc.

- Insulator are of Plastics, Rubber, Wood etc.

- Types of cable are

   1 core

   2 core

   3 core / 3.5 core

   4 core

   5 core.

• Classification of cables depends on insulation :

- PVC : Poly Vinyl Chloride

- XLPE : Cross Linked Poly Ethylene

- FRLS : Flame Retardant Low Smoke

- MICS : Mineral Insulated Copper Sheathed

- PILC : Paper Insulated and Lead - Alloy Sheathed.

• Conductor use in cable is either tinted copper or tinted aluminium.

- Indian Standard (IS) - 8130 for polycab

- International Electrical Code (IEC) - 60228

- British Standard (BS) - 6360

• Insulation : 

- IS - 7098

- IEC - 60502

- BS - 6622

• Underground Cable Laying in HT or HV side : 

                       Depth.           Width

- 11 KV          120cm.            90cm

- 33 KV          120cm             90cm

- 66 KV            2 mts.            90cm

Where,  1.5 sq.mm -- 16 sq.mm is Wire.

                35 sq.mm -- 1000sq.mm is HT                                                   single core.

                35 sq.mm --- 400sq.mm is 3 or                                                   multiple core.

• Procedure for cable laying :

- Depth and width according to thickness and size of cables.

- Sand laying 15cm or Sand bending 15cm.

- Warning ⚠️ tape

- Sand sourcing

- Cover the area

- Do the levelling and laying the cables.

• Selection of Power Cable are 

- Max operating voltage ⚡ 440v - 1.1kv

- Load to be carried

- Faults level

- Possible over Loading

- Length and Voltage drops

- Mode of installation conditions environment properties.

- Flame Retardant properties

- Normal operating Underground 90° C

- Short circuit withstand 200° C

- Megger test of cables connection.

• Types of Cable testing :

- Continuity test

- High voltage test

- Conductor Resistor test

- Short circuit test

- Non electrical test.

• Cables tray :

Two types of cables tray

- Perforated cable tray

- Ladder tray

• Perforated cable tray :

 This tray are available in aluminium only.

• Ladder tray :

 Ladder tray are available in aluminium, steel and iron.

- After some time installation of cables trayrust / dust will form on the steel and iron.

So we usually avoid steel and iron and use aluminium.

- Length and width are dependent on number of cables.

- For manufacturing of cables tray we should follow 

*NEMA (National Manufacturing Association).*