Classification of Underground Cables

Underground cable's basic terms and definition is already discussed in Underground Cable Basics . In this article we'll discuss how these cables are classified and how many types of cables are there in Industry.

Classification of Cables

Things may be classified on many aspects and similar is the case with cables. There are several ways of classifying cables. These includes classification of cables on the basis of :

• No. of Conductors in Cable
• Voltage Rating of Cable
• Insulation Used in Cable
• Power To Be handled in Cable

No. of Conductors in Cable

On the basis of number of conductors in the cable, cables are of two types viz Single core cables and 3 core cables. Single core cable have only one conductors and the diagram is shown in Underground Cable Basics while three core cable has three conductors and they have bedding and filler too. so on the basis of number of conductors cables are of two types :

• Single Core Cable
• 3 Core Cable

Voltage Rating of Cable

Cables may be classified on the basis of voltage rating also :

• LT Cables : Cables up to 1000 Volts or 1kV are called LT (Low Tension) or LV (Low Voltage) cables.
• HT Cables : Cables from 1001 volts to 11000 Volts or 11kV are called HT (High Tension) or HV (High Voltage) cables.
• ST Cables : Cables from 11001 volts to 33000 Volts or 33kV are called ST (Super Tension) cables.
• EHV Cables : Cables from 33001 volts to 66000 Volts or 66kV are called EHT (Extra High Tension) or EHV (Extra High Voltage) cables.
• Oil & Gas Filled Cables : From 66 kV to 132 kv Oil and Gas Filled cables are used.
• EST Cables : Cables Used above 132 kV are called EST (Extra Super Tension) cables.

Insulation Used in Cable

Cables are also classified on the basis of insulation provided in the cable. Following are the type of cables on the basis of insulation used in the cable :

• PIC or PILC : Paper Insulated Cable - Paper is used as insulation to the conductor.
• PVC : Poly Vinyle Chloride Cable - PVC is used as insulation to the conductor.
• PE : Poly Ethylene - Poly Ethylene is used as insulation to the conductor.
• PTFE : Poly Tetra Fluoro Ethylene - PTFE is used as insulation to the conductor.
• XLPE : Cross Linked Poly Ethylene - Cross Linked Poly Ethylene is used as insulation. This is most commonly used cable in Industry.

Power To Be handled in Cable

On the basis of amount of power to be transferred through the cable, cables are classified into two categories. These are

• Power Cables : If large amount of power is to be transferred then these are called power cables. These are further classified on the basis of voltage at which power is to be delivered.
  1. Low Voltage Power Cable : If the voltage in the cable is less then 1000 Volts or 1kV then the cable is called Low Voltage Power Cable.
  2. High Voltage Power Cable : If the voltage in the cable is above 1000 Volts or 1kV then the cable is called High Voltage Power Cable.
• Control Cables : If the cable is used to carry very low power signal generally for controlling equipments then the cables are called control cables.