International. France's largest library (BnF) – and one of the most important in the world – has chosen Emerson's drive and motor solutions to maximize the reliability of its air conditioning equipment.
The BnF's collections comprise fourteen million books and periodicals, as well as manuscripts, prints, photographs, maps and letters, musical scores, coins, medals, sound files, videos, multimedia, sets, costumes and much more.
To protect its treasures, the BnF was well aware of the need to maintain an extremely reliable air conditioning system. The initial project was defined with this premise: to replace the existing asynchronous variable speed drive with a new drive system to power the air conditioning pump, responsible for half of the reading rooms in the library.
"The results of an energy optimisation study revealed in particular that the operational efficiency of the existing application was reduced to as little as 50% in the winter. The ROI calculation showed that it would make much more sense to switch the asynchronous drive system to Leroy-Somer's high-performance Dyneo® synchronous technology," explains Jérôme Hardy of GED Adrem, a partner company of the Leroy-Somer service network.
To control the variable torque load of pumping and ventilation applications (quadratic torque loading), Emerson implemented a solution equipped with a Leroy-Somer Dyneo LSRPM 250 (85 kW) motor and a Unidrive M600 speed variation unit from Control Techniques.
The permanent magnet synchronous motor is perfectly suited to applications of this type, offering greater efficiency (up to 96%) over the entire operating speed range. Another advantage, in terms of cost, comes from control without feedback sensors. This function, integrated into the Unidrive M drive unit, simulates an encoder input with a high degree of accuracy.
"With this solution we not only eliminate the cost of encodering, we also reduce the number of components and therefore the probability of a failure," added Jérôme Hardy.
The BnF gave top priority to the service life and availability of the equipment, as well as the support service. Leroy-Somer was commissioned as the sole supplier with confidence in its ability to ensure operational safety, ensuring the highest performance and complete interoperable compatibility of components. A comprehensive approach was adopted with the permanent objective of maximizing reliability:
"We requested the Premium service procedure from the Leroy-Somer center. This extremely rigorous method uses multiple control points during installation and commissioning. Operations such as element alignment control, dielectric measurements and phase balancing offer real benefits in terms of reliability and energy consumption," adds Jérôme Hardy.
Since then, the equipment has been monitored, in particular by means of vibration analysis, and the resulting data has been compared with the data collected during commissioning. This makes it easier to detect shunts, premature wear and overconsumption.
The original engines, also from Leroy-Somer, were revised and remain as safety backups. The set is connected to the BMS (building management system), an automated and centralized monitoring system that gives the speed clock. The next phase will consist of carrying out a study of the energy efficiency of central air treatment systems and replacing their drives. Further measures to modernise the system are also planned in the coming years.
