September 2021

34 n ENERGY EFFICIENCY September 2021 www.drivesncontrols.com Drive-controlled fans help cows keep their cool C ows in barns require proper ventilation to support their well- being and avoid illness. Large fans hung from the roof can help to dry the floor and lower humidity, reducing hoof and udder hygiene issues. The pulses of air also remove smells and gases produced by the livestock’s urine, manure and breathing. During summer, excessive heat can be uncomfortable for the cows, leading to lower milk quality and production. Ventilation systems can increase airflows, reducing the risk of heat stress, while pulses of air on the cows’ backs produce a cooling sensation. The French agricultural equipment supplier Bioret-Agri has been providing farmers with animal comfort products since 1983, with a particular focus on dairy cows. When mounted in a barn’s rafters, its Cyclone 360 ventilation system – based on a system from the Canadian manufacturer Ventec – delivers 360° of airflow, reducing the heat stress on cows. When Bioret-Agri was looking to improve the performance of the ventilation system and to cut its power consumption, it decided to move from an induction motor (IM), which provided only a simple on/off control, to a permanent magnet (PM) type, which offered the opportunity to add variable- speed control depending on the barn temperature. This would reduce both energy consumption and noise levels. The 2.2kW electrically-commutated brushless PM motors operate at up to 1,800 rpm, driving the 1.83m-diameter fans at 300 rpm via a belt. The system can move 80,000m 3 of air per hour at speeds of up to 4m/s. When the temperature is between 3°C and 18°C, the ventilation system operates at 20% of its top speed. If the temperature rises above 18°C, the motor speed increases. The new ventilator consumes up to 32% less energy than the previous IM-based model. In a typical installation in France this could save farmers up to €250 a year per ventilator. With some barns being up to 100m long, multiple ventilators are often needed along the length of the roof. Bioret-Agri therefore, looked for an inverter drive for its redesigned ventilation system that could communicate with the other ventilators to ensure a uniform airflow throughout the building. It chose Delta Electronics’ ME300 vector control drive, which is 60% smaller than the Taiwanese company’s previous-generation drives, allowing it to be integrated inside the Cyclone 360. Screwless terminal blocks simplify manufacturing, while built-in EMC filters save space and the need for parts. Covid restrictions posed challenges for Bioret-Agri and Delta when developing the new ventilator. Although the drives could be parameterised to match the motor, restrictions in accessing the motors on-site meant that the system had to be optimised remotely. The speed of multiple ventilators can be synchronised via an 0-10V analogue output that links the inverters in a chain. Delta plans to integrate a flying catch capability in the drives’next firmware upgrade. This will allow them to search for the correct drive speed, if the fan is already rotating, without having to bring the rotor to a standstill. “This has been an exciting project, much different from typical industrial applications,” says Jean-Charles Cuzin, a field application engineer at Delta. “Covid added to the development challenges, but resourcefulness and dedication by the team ensured we overcame them.” n If cows get too hot, they can become stressed, affecting the quantity and quality of the milk they produce. A French firm that supplies fans to cool cows in barns, says that by adopting VSD-controlled PMmotors, it has cut the fans’ energy consumption by up to 32%, saving farmers more than £200 a year for every fan. Bioret-Agri’s ventilation system offers an energy- efficient way of keeping cows cool and productive