1. What are the different types of cable accessories?
2. What are the objectives to be achieved by Termination Kits?
3. What are the objectives to be achieved by joints?
4. List down the various types of cable accessories.
5. Explain Heat Shrink technique
6. Explain Cast Resin technique

Types of cable accessories

i. Terminations :

Termination kits serve as a connection to electric apparatus or machines or switchgear and are further categorized as Indoor and Outdoor Termination kits.

Indoor Termination kits (IDT) : IDTs are used for the indoor application i.e. for termination at Panels, Transformers etc.

Outdoor Termination kits (ODT) : ODTs are used for terminating at switchyards, outdoor substations, on poles etc. where these are directly exposed to atmospheric conditions.

ii. Joints :

Cable joints connect lengths of cables in long routes or at points of repair. These facilitate transfer of power over long distances as many a times it is not possible to supply long cable lengths due to various reasons such as manufacturing & transportation constraints, site conditions etc.

There are two types of joints :

1. Straight Through Joint : These joints are required when two cables having the same type of insulation are to be joined ( eg :XLPE to XLPE insulated cable).

2. Transition Joint : When two cables having different types of insulation are required to be joined, transition joints are required ( eg : XLPE insulated cable with PILC insulated cable etc ).

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Objectives to be achieved by Termination Kits

The following objectives must be fulfilled :

• connection of the conductor
• stress grading at screen cut point of both radial & longitudinal stresses for medium and high voltage cables
• Avoid ingress of water and to protect against ambient influences
• protection of core insulation (e.g. against U.V. radiation)
• insulation from earthed parts

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Objectives to be achieved by joints

• The following objectives must be fulfilled :
• connection of the conductors v insulation of the conductors
• reinstatement of the elements of the cable for Medium & high Voltage Cables
• protection against all ambient conditions of the ground
• establishment of branch points for service cables in low voltage cables.

List of various types of cable accessories.

The various types of cable accessories are :

• Heat Shrink type
• Pre-moulded /Pre-fabricated type (Factory Moulded)
• Cold Shrink type v Push-on type
• Cast Resin ( poly-eurethene / Epoxy compound filling ) type
• Cast Iron ( bitumen compound filling ) type

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Heat Shrink technique

The heat shrink technique is a versatile technology which can be used for a variety of applications vis-a-vis cable applications.

Thermoplastic based materials are used for manufacture of heat shrink components. After cross-linking process the material is moulded into shape, expanded in hot condition itself and suddenly cooled.(eg: expanded insulating tube, break-out etc). The component remains in the expanded form. This pre-stretched form when heated recovers to its original dimensions. This is termed as the Shape Memory Phenomenon. In this process the tube "shrinks" on to the subjacent parts.

As a heat source, a hot air blower or soft flame may be used. Shrink on products are easy to install, simple, quick and independent of ambient temperature. They can also be used, because of their flexibility, as additional protection against mechanical stress. These accessories are best suited for application in 1.1 kV to 33kV range.

Cast Resin technique

This is a time tested method of jointing & terminating of cables. In this technology, basic insulation is provided by lapping of insulating tapes. Stress grading, in case of MV & HV cables, is provided by means of stress-cone which is built-up by lapping of semi-conducting tapes. Cast-resin compound when set, gives protection against mechanical damage & moisture ingress. These accessories are successfully in service in 1.1 kV to 33kV range.

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