My Mind, My Heart, My File

Substation Design and Layout

The First Step in designing a Substation is to design an Earthing and Bonding System.

Earthing and Bonding

The function of an earthing and bonding system is to provide an earthing system connection to which transformer neutrals or earthing impedances may be connected in order to pass the maximum fault current. The earthing system also ensures that no thermal or mechanical damage occurs on the equipment within the substation, thereby resulting in safety to operation and maintenance personnel. The earthing system also guarantees eqipotential bonding such that there are no dangerous potential gradients developed in the substation.

In designing the substation, three voltage have to be considered.

1. Touch Voltage: This is the difference in potential between the surface potential and the potential at an earthed equipment whilst a man is standing and touching the earthed structure.

2. Step Voltage: This is the potential difference developed when a man bridges a distance of 1m with his feet while not touching any other earthed equipment.

3. Mesh Voltage: This is the maximum touch voltage that is developed in the mesh of the earthing grid.

See detail : Substation Design and Layout