- In early days, there was a little demand for electrical energy so that small power stations were built to supply lighting and heating loads.
- However, the widespread use of electrical energy by modern civilization has necessitated producing bulk electrical energy economically and efficiently.
- The increased demand of electrical energy can be met by building big power stations at favorable places where fuel (coal or gas) or water energy is available in abundance.
- This has shifted the site of power stations has to be supplied to the consumers.
- The electrical energy produced at the power stations has to be supplied to the consumers. There is a large network of conductors between the power station and the consumers.
Over voltages due to switching surges
System faults and other abnormal conditions
Principles of insulation co-ordination