EDF's Durance Verdon hydroelectricity basin consists of 17 dams and 30 power stations with a total installed capacity of 2200MW and production of 6.5 billion kWh. Most of the power plants have been in use thirty years or more and maintenance operations are vital to ensure optimum production. Verlinde hoists are installed at all plants and have to meet very specific operating conditions.
Power station maintenance
To ensure there is no lack of coherence between the various power stations, the Mediterranean Production Division (Unité de Production Méditerranée) took the decision that lifting equipment would be standardized for renovation operations. Verlinde series VT5 hoists were selected for the modernisation of a significant part of the installed fleet. These hoists were installed principally at the following power stations: Serre-Ponçon, Manosque, St Tulle II, Oraison. Radio control was given preference over cable control for its operating flexibility and simplicity as well as for reasons of equipment standardization. Likewise, there was no hesitation in choosing variable speed both because of its high-precision handling qualities and for its rapidity of up / down and horizontal travel. Variable speed is also a safety factor for special operations in hostile, restricted, badly lit environments at great depth. Indeed, a number of special operations are necessary in wells or on valves or seals and require hoisting heights of up to twenty-five meters or more.
Diversity of requirements
Even if all power stations share the same goal – maximum production of electricity – due to the geographical location of plants and to types of dams, lifting equipment must be appropriate to plants' specific operating and maintenance needs. For instance, the Castillon power station has a sloping area to enable the heavy parts of generating units to be taken out of the lower part of the station. The loads are then hoisted by another gantry crane located on the face of the dam structure. For the EDF technical departments in charge of lifting equipment, Verlinde is an important partner due to its ability to adapt equipment to highly specific needs requiring highly inventive problem solving by engineers.
In the words of Denis Martinez, Chargé d’affaires of the maintenance inspection team of EDF GMH Méditerranée. "Clearly, our lifting equipment is seldom used but for all that it must be immediately operational and able at any time to operate at maximum load. These vital aspects of our maintenance service must be reliable and efficient at all times. For reasons of cost and reactivity we also have to keep the management of our spares stocks as simple as possible and that means first and foremost standardization of our lifting equipment. The third important aspect is contact with our supplier. Verlinde is always ready, if needs be, to adapt their equipment to our needs. Locally available integrators also means our responsiveness is at a high level. Meije, a company with whom we regularly work is in that respect a reliable partner with whom we can plan upgrades and customization of Verlinde equipment". Indeed, Meije, with its workforce of 25 and integrated engineering department, provides excellence not only in the area of hoisting but also for electromechanical engineering, industrial electrical engineering and winding. These additional activities make it a local partner able to analyse problems and provide solutions for its customer EDF GMH.