The Nogent-le-Roi wind turbine BEST-Romani had the specifications below (see also the summary in figures):
- Three blade propeller fixed-pitch made of alloy of light aluminum-zinc (AZ4G). Profile and structure of type « airplane wing ». Length of blade: 15 meters or an overall diameter of 30.19 meters. Axis of rotation to 32 meters above the ground.
- 6-pole synchronous generator with a voltage of 3000 volts transformed into 15,000 volts for connection to EDF. Rated apparent power of 800 kVA or 650 kW. The propeller was connected to the generator by a mechanical linkage involving two coaxial gear trains epicyclic gears.
- Rotation speed: 47 revolutions / minute. Rotation speed of the alternator: 1000 Trs / m (invariable as regulated by the frequency of 50 Hz network EDF).
- A clutch allowed to disconnect the propeller of the alternator at the time of coupling to the network.
- The system was equipped with a brake disc diameter of 1.8 meters dissipating a power of 2 million-pounds. It was important to be able to stop quickly in case of strong the wind otherwise the wind could provide as much energy as the brake pads removed upto to the destruction of the brakes lining and the runaway of the machine that worked in "fan mode".
- Redundant emergency brake were installed to prevent runaway:
- by connection of the alternator on an electrical line of resistance nickel silver cooled by ambient air. This brake, theoretically for "backup" was actually used systematically to relieve the disc brake pads.
- by a system of spoilers embedded in the leading edge of the blades (aerodynamic braking). Each spoiler was held in its housing by a return spring and a mass calibrated individually according to the position of the spoiler on the leading edge of the blade. Given a certain linear velocity, the centrifugal force caused the ejection of all spoilers at the same time thereby altering the aerodynamic profile of the blade. The circumstances of the tests were like this unique system has never been used, the machine never having packed with this propeller.
- When stopped, a system of locks avoided any accidental starting of the propeller.
- The unit was housed in a nacelle comprising a platform at the top and accessible to staff, which were installed on several oil-hydraulic systems onboard (lubrication, brake control, the clutch and locks).
- The weight of the navelle fitted plus the propeller was more than 30 tons.
- Consists of two truncated cones of unequal length assembled by their base in opposition.
- The smallest cone was followed suit inside the pylon tripod and was based on a thrust bearing.
- The largest cone emerged from the tower in full.
- The nacelle (above) was based on the upper end of the pivot. One accessed thereto by a vertical ladder housed back of the pivot between the two metal strips of aerodynamic profiling.
- At the junction of two cones, a circular band of metal about 20 cm was welded. It allowed the rotation of the assembly on a wheel gear recessed vertically in the upper part of the tripod.
- With these devices, the wind turbine operating in « weathervane » and was moving almost automatically in the direction of the wind (propeller backwards). It was possible to control the orientation of the pivot by a servomotor controlled mechanism from the experimental room. It was also possible to control the orientation of the windsock at the top of the tower of 60 meters.
- The pivot weight: 20 tons.
The tripod pylon:
- Structure of metal lattice type.
- Both feet facing north based on a concrete block of 70 m3 (about 150 tonnes) each through a steel plate.
- The third leg (south) based on a mass of 60 m3 (about 100 tons). This foot was secured by a locking rod.
- The weight of the tripod was 100 tons.
On the ground:
- The generator voltage was raised from 3 000 to 15,000 volts for connection to the EDF network.
- The electric line outside of the experimental station was connected to the SNCF substation in Maintenon by two sections:
- The first, temporay and since disappeared, ran along the D 148 to the path which, skirting the castle grounds, liaises with the D 104 (Path of Chandres).
- The second was in direct Maintenon through fields and woods.
- At the junction of two sections, a manualy controled air inverter allowed to connect on a 15,000 volts third line serving directly Nogent-le-Roi. This possibility has been used once officials fearing that EDF production - variable - the wind does disturb the power supply of the city and its inhabitants.
The tilting :
- The whole machine (150 tons) was able to be tipped up, ie it was possible to make it describe a circular path in the space of a quarter circle to bring it to the horizontal.
- To do this two winches used in coal mines had been placed on two concrete blocks of 50 cubic meters, including 8 cubic meters buried them with a mass of about twenty tons:
- The first winch (called "North") was connected to the upper platform of the tripod with a pulley system consisting of a multi-strand steel cable of a diameter of 25-30 mm for 6 or 8 strands.
- The second winch (called "South") was connected to the connecting rod foot south by a pulley system similar but longer.
- This equipment allowed, after having the propeller facing north; brought the blades in the proper angular position and locked all, to switch all of the wind turbine so thatat the end the propeller was in an horizontal plane.
- The axis of each blade was then in the axis of the terrace of the measuring station or of one of the two branches of a "Y" in scaffolding tube type "Entrepose". The nose of the propeller was then in a hole in the connecting part of the "Y" and the measuring station. This allowed to clear the propeller spinner, fairings, gears or the alternator without difficulty when it had been almost impossible on a machine not tiltable.
Station of control and measures:
- The research station on the ground included a room for experimentation, measurement and control.
- At a time when computing was in its infancy, all the measures was run by sophisticated electrical devices.
- The initiation was done by a series of chained operations requiring the presence of many contactors, relays and a multitude of primary contacts (a total of 450 contacts in total).
- The installation should always be in working order so that experiences can take place at all wind regimes available regardless of when they presented themselves that is very randomly. To ensure that everything was in working order in case of wind or to enable rapid troubleshooting, Pierre Jean Cavey had labeled the hundred auxiliary contacts and was plotted on a diagram to quickly diagnose failures.
- The station also included many measuring instruments: barometers recorders, a psychrometer, an Ailleret type energy gaugean other recording speed and wind direction from measurements made on nine pylons, torque, the forces on the pivot measured by resistance wire extensometers (strain gauges), galvanometers, etc. ...
- It housed a group converter connected to the EDF network. It was running a DC generator for generating the current necessary for excitation of the inductor generator placed in the nacelle. Indeed the configuration of the latter did not install the exciter in the nacelle which already hosted the clutch and a gear train. The group also runned one second DC generator that powered a battery backup designed to store enough current to power the generator in case of failure of the exciter.
When the wind was favorable (greater than 2.5 Beaufort and less than 8 Beaufort scale, the tests could be performed. The startup of the turbine was performed in a specific sequence:
- Exposure to air. Operating in "weathervane" it was moving, as said above, almost into the wind (back propeller). « Almost », because for reasons that remain unexplained, the apparatus was moving with a systematic deviation of about 13 degrees to the true meaning of wind. The windsock tower of 60 meters allowing automatic adjustment. If necessary, the head of the station could also make a manual adjustment.
- The generator was then turned on, connected to the network, the propeller stopped and disengaged. This configuration allowed the generator to synchronize with the frequency of the EDF network (50 Hz) and to stabilize its speed to 1000 rev / min.
- It is only then that the disc brake freed the propeller. Mating screw - generator was done then by engaging the propeller on the generator.