Overvoltages are an increase of voltage on the electric line, measure between two conductors, which can produce damage on the installations
and the electric equipments.
There are two different types: transient and permanent.
Permanent or power frequency overvoltages are characterized by relatively long duration (several cycles) There are usually caused by:
- Defect connection of the neutral.
- Power consumption lowered.
Transient overvoltages are very short duration increases in voltage
between two conductors or between a conductor and the ground. They
can be on account of atmospheric electrical discharges (lightning), by
switching or by electrical faults (contact with earth or short circuit).