Grading of cables is done in order to:
- Achieve uniform electrostatic stress
- Reduce the size of cable
- Reduce insulation being used
- All of these
Correct answer: 4. All of these
Grading of cables is defined as the process of achieving uniform electrostatic stress in the dielectric of cables.
In a single-core cable the electrostatic stress is maximum at the conductor surface and it decreases as we move towards the sheath of the cable. This unequal stress distribution in a cable has two major disadvantages:
- A greater thickness of insulation is required
- Unequal distribution might lead to the breakdown