In spite of the growth of laboratory methods designed to predict the long-term performance of insulators, there has always been and will probably always be a need for test stations operating under real service conditions. Such stations not only provide a validation for laboratory tests which rank insulators in order of merit but also have helped to establish correlation between acceleration factors in the laboratory and real life experience.

One station which has been supplying exactly such input on insulator performance is the Martigues Test Station situated just outside Marseille, France and only meters from the Mediterranean. Martigues was originally set-up by Electricité de France (EDF) in 1968 as one of two test stations built to study the behaviour of glass and porcelain insulators under marine and industrial pollution. The goal was to establish design requirements and dimensioning rules in such an environment. The other station, St Rémy des Landes located in Normandy, was closed during the 1980s and this made the testing work being done at Martigues that much more important.

	Test station lies only meters from Mediterranean shore.

Eric Spangenberg, a specialist in dielectric behaviour of electrical equipment at EDF, explains that over the years Martigues’ role has expanded beyond studying ceramic insulators to also include the ageing of composite insulators. “For these insulators,” he says, “we were particularly interested to compare laboratory ageing tests with findings at Martigues to see if the acceleration factors being proposed were accurate or not.”

Spangenberg goes on to note, however, that today there is no longer talk about such generalized acceleration factors since it has been found that these depend a great deal on each particular insulator design and material. Spangenberg also notes that the general viewpoint in the industry today is that the acceleration factor in an ageing chamber depends primarily on the specific parameter being studied.