Main Grid Equipment Overstress Analysis

In accordance with the definitions in the Grid Procedures, it is ONS’s attribution to perform annualequipment overstress analysis caused by short circuit, load current, time constant and other types of request. Such analysis are intended to ensure operation security, as theycan identify in a three years advance scenario, possible cases of network overstress, which are sent to MME and ANEELfor analyses.

For the coordination and implementation of this process, ONS created the Working Group for High Voltage Equipment Overstress Analysis (GT-AS), composed by Transmission, Distribution and GenerationAgents. The analysis conducted annually by the GT-AS are part of the PAR processes and cover the Main Grid equipment, DIT and relevant generation and distributioninstallations.

In this period, 250 equipment were identified as overstressed. Figure 7 shows a summary of the overstress by type of equipment. The highest indication of overstress was found in circuit breakers, followed by current transformers and disconnection switchers. There was also an evidence of two grounding transformersoverstress.

Figure 7 – Overstress Evidence by Type of Equipment