
Surge Protection Devices (SPD)
Electrical distribution lines can sometimes be subjected to transient overvoltages (TOV) and
power surge conditions. The creation of those conditions can be related to several causes.
Transient overvoltage conditions can be caused by the following [3]:
(a) Line-to-ground fault, particularly on an ungrounded or resistance-grounded system
(b) Loss of neutral ground on a normally grounded system
(c) Sudden loss of load or generator overspeed, or both
(d) Resonance effects and induction from parallel circuits
Direct lightning strikes can inject a significant current surge on a distribution line. Also,
lighting strikes within ...