MEIJE installs VERLINDE EUROBLOC VT hoists for the renovation of 6 EDF hydroelectric dams on the River Maulde.
There are some 2,250 hydroelectric installations of various sizes in Metropolitan France whose power varies from 1,000 watts to several hundred megawatts. 436 of them are operated by EDF. Out of the total installed capacity of 25.4 gigawatts nationwide, EDF produces no less than 20 gigawatts or 13% of the company's total energy production.
A smallish watercourse 70 km long whose source is in the commune of Gentioux-Pigerolles (Creuse department) and mouth at Saint-Léonard-de-Noblat (Haut-Vienne department) where it flows into the River Vienne is the River Maulde on which EDF operates six dams with a combined power output of 18 megawatts. Located at Martinex, Fleix, Langleret, Villejoubert and Lartige, the six gravity dams, most of them Ambursen type dams, roughly16m high, have buttresses spaced at intervals and are of identical design.
Improved efficacy for renovation operations
Each dam is made up of five sections (with the exception of Lartige) on four of which are mounted a bulb unit fitted with an asynchronous generator while the fifth section is used when an emptying operation is necessary.
Each section equipped with a bulb unit is made up of a water intake tower, a penstock with a 90° elbow and a butterfly type slide valve. Until now, the EDF maintenance and servicing teams used a 15-tonne capacity hoist that they moved from one group to another and from dam to dam.
EDF is at present faced with the challenge of heavy renovation works on each of the six dams' sections. Alluding to this operation and on behalf of Meije, José Lima explained that with a single hoist the operation would take too long. "the invitations for tenders put out by EDF therefore involved, on the one hand, the renovation of the existing monorail tracks and supports and, on the other hand, the supply of five identical and easily movable mobile monorail hoists. Our bid with Verlinde hoists won the contract because it precisely met the specification sheet conditions both in terms of price and of equipment quality.
EDF decided to install a Verlinde EUROBLOC VT standardized 2m/M5 hoist on each section of the dam being renovated, each with a lifting capacity of 15 tonnes and lifting height of 15 m. This hoist enables operations on the heaviest parts of the bulb group located in the section at the base of the dam. The five sections equipped in this way enable simultaneous work on the five groups and keep production downtime to a minimum. After 12 to 16 months' work, when renovation work is completed, the hoists can be easily dismounted using a screw plate system we have designed. They are then set up on the next dam."
VERLINDE EUROBLOC VT monorail girder hoist
For outside operations and in moist environments, the hoisting and travel motors, along with the electric cubicle of the selected EUROBLOC VT hoist, provide protection IP66. The variable speed travel motors limit both current inrush and load sway and the maximum load lifting speed is 3 m/min. The hoist had to meet other specific requirements, like for instance the provisioning of an iodide projector 400W in order to light up the lower part of the section thus enabling the operator a perfect view of the work in hand. The equipment is controlled either by a wired keypad or by a VERLINDE EUROMOTE H5 remote control. They are interchangeable by using a pluggable connector. On this type of worksite where the operator has to manipulate loads in a very specific environment, numerous safety features are indispensable, like the load limiting system with its strain gauge, the limit switches and sound and light signals.
MEIJE, member of VERLINDE's EUROPONT network.
For José Lima, co-manager of MEIJE with Agnès Ferret, "Our company with its workforce of 25 is a member of the Verlinde Europont network and we operate mainly in the South of France: Aquitaine, Charente-Midi Pyrénées, Languedoc Roussillon, …We can meet all orders for girder or box girder cranes, whether they be overhead, suspended, gantry or semi-gantry, with spans of up to 35m and lifting capacities of up to 80 tonnes. We frequently work with EDF and recently, for their Méditerranean production unit, we supplied VERLINDE VT5 hoists for maintenance operations".