With the development of modern power system to the direction of extra-high voltage, large capacity, far distance transmission and application of advanced technologies the demand on the safety, stability and economic operation of power system became higher.

Description of Seasonal Influence on Safety of Substation Grounding

A good grounding system is the fundamental insurance to keep the safe operation of the power system. The good grounding system should ensure the following:

¨ To provide safety to personnel during normal and fault conditions by limiting step and touch potential.
¨ To assure correct operation of electrical devices.

¨ To prevent damage to electrical apparatus.
¨ To dissipate lightning strokes.

¨ To stabilize voltage during transient conditions and therefore to minimize the probability of flashover during the transients

As it is stated in the ANSI/IEEE Standard 80-1986 "IEEE Guide for Safety in AC substation grounding," a safe grounding design has two objectives:

¨ To provide means to carry electric currents into the earth under normal and fault condition without exceeding any operational and equipment limit or adversely affecting continuity of service.

¨ To assure that a person in the vicinity of grounded facilities is not exposed to the danger of critical electrical shock.