HIGH VOLTAGE ENGINEERING
OVER VOLTAGES IN ELECTRICAL POWER SYSTEMS NATURAL CAUSES OF OVER VOLTAGES Introduction Examination of overvoltages on the power system includes a study of their magnitudes, shapes, durations, and frequency of occurrence. The study should be performed at all points along with the transmission network to which the surges may travel. Types of Overvoltage • The voltage stresses on transmission network insulation are found to have a variety of Origins. • In normal operation, AC (or DC) voltages do not stress the insulation severely. • Overvoltage stressing a power system can be classified into two main types: External overvoltage: generated by atmospheric disturbances of these disturbances, lightning is the most common and the most severe. Internal overvoltages: generated by changes in the operating conditions of the network. Internal overvoltages. Lightning Over voltages Lightning is produced i...