Aterramento temporário: considerações sobre o dimensionamento elétrico e mecânico do conjunto

Abstract

The temporary protective grounding is a procedure of great importance for the security of teams working with the maintenance of electric power system. Its function is to guarantee the workers safety not only in the event of an accidental energization but also concerning the many types of existing inductions. The temporary protective grounds were submitted to non-normalized 17.5 and 29.0 kA three-phase short-circuits tests, in order to reproduce the way in which they are installed in substations at nominal voltages of up to 500 kV. The main points to be considered in the specification process are presented and discussed. The results have showed the forces that appear in the moment of an accidental energization are very high, and the most likely point of failure is located in the connections of the cable to the clamps, reinforcing the need to take the asymmetrical current into consideration during the specification process. The voltage drop in the temporary protective grounds was also measured and the data may be used in similar applications.