The full name of S. L. type cable is __________.

Classification of cable based on construction

Belted cable:

• In such cables, the conductors (usually three) are bunched together and then bound with an insulating paper ‘belt’.
• In such cables, each conductor is insulated using paper impregnated with a suitable dielectric. The gaps between the conductors and the insulating paper belt are filled with a fibrous dielectric material such as Jute or Hessian. 
• There are some limitations of such construction. Since the electric field is tangential, the insulation provided is stressed. As a result, the dielectric strength falls over time. Hence, such construction isn’t preferred for voltage levels above 11 kV.

Screened cable:

It is further divided as H type and S.L. type cables:

H-Type Cable:

• H-type cables are high-voltage paper-insulated cables designed for underground power transmission. They are mainly used for voltages up to 66 kV.
• The three cores are individually insulated with paper and then covered by a metallic screen/cover. These metallic covers are perforated. As a result, such construction allows the three metallic screens to touch each other.

S. L. Type Cable:

• The full form of SL-type cable is Separate Lead type cable. Such construction is limited for voltages up to 66kV only.
• SL-type cables are an improved version of H-type cables, used for underground high-voltage power transmission. They feature separate lead sheaths over each core, providing better insulation and fault protection compared to H-type cables.

Pressure cables:

• For voltages beyond 66 kV, the electrostatic stresses in the cables exceed the acceptable values and solid cables become unreliable.
• This occurs mainly because voids are created when voltages exceed 66 kV. Hence, instead of solid cables, we use Pressure cables.
• Typically, such cables are either oil filled or gas filled.