Place of SEM substations in electricity transmission networks
High and extra-high voltage substations

In 1996, the CIGRE (Conférence Internationale des Grands Réseaux Électriques), which brings together operators and manufacturers to share information and publish recommendations, carried out a survey of SEM substation feedback. The survey gathered information on the state of the SEM substation fleet, damage statistics and maintenance practices.

The main information gathered on the equipment in service at December 31, 1995 is as follows:

• the total number of cells (equipped with circuit breakers) is around 30,000;

• The oldest equipment was commissioned in 1965;

• the average age is close to 9 years;

• Japan alone has 8,600 cells, more than a quarter of the total;

• between 30% and 40% of cells are installed outdoors;

• Approximately 80% of the cells installed correspond to voltages between 72.5...