Verlinde integral to hydroelectric dam project

EDF operates six dams on the river with a combined power output of 18megawatts, which each dam, bar one, made up of five sections.

Each section equipped with a bulb unit is made up of a water intake tower, a penstock with a 90deg elbow and a butterfly type slide valve.

And until recently, the EDF maintenance and servicing teams used a 15t capacity hoist that they moved from one group to another and from dam to dam.

Faced with the challenge of heavy renovation works on each of the six dams' sections, EDF put the job out to tender.

José Lima co-manager of Meije, part of the Verlinde Europont network explained: "The invitations for tenders put out by EDF, 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 standardised 2m/M5 hoist on each section of the dam being renovated, each with a lifting capacity of 15t and lifting height of 15m."

The 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," Lima added.

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 3m/min.

The hoist had to meet other specific requirements, 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 necessary, such as the load limiting system with its strain gauge, the limit switches and sound and light signals.

Lima added: "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 80t.

"We frequently work with EDF and recently, for their Méditerranean production unit, we supplied Verlinde VT5 hoists for maintenance operations".