Analysis of simultaneous line-to-ground faults

A CERTAIN PERCENTAGE of the faults on power systems occur simultaneously at different points in the circuits. Such faults may result from a ground at one location on a circuit which raises the voltage on a healthy phase so that a flashover occurs at a second location. Such faults may also occur on circuits which are physically close to each other, as two circuits on the same poles which flash over because of the same lightning disturbance. It has been estimated that up to 20% of faults on double-circuit lines involve conductors of both circuits.