Drives & Controls March 2022

Storage elevator rises to temperature challenges of Dubai A utomated storage elevators are usually driven by electric motors, with the aid of counterweight systems. When these systems are located in environments where the temperature can vary widely, the equipment must be able to withstand extreme temperatures as well as carrying heavy loads. This was the case for Moffett, an automated storage firm based in Ireland, when it took on its first international contract in Dubai. The project involved a system for a 30m-high building with a throughput of 85 pallets per hour. The system had to be able to lift and lower pallets reliably in temperatures that could range from –25°C to +40°C. In addition, Moffett needed to be able to manoeuvre pallets weighing more than 1,500kg at speeds of 1m/s at heights of up to 30m – a similar height to a three-storey building. To achieve rapid acceleration and deacceleration of the large number of pallets, Moffett opted for an inverter-driven system. The weight of the loads can vary widely, so the lifts needed an auto- correction function similar to those used to compensate for changes in weight in human-carrying lifts as people enter or leave. Moffett got in touch with the Craigavon- based drives specialist Technidrive, which worked with the motor supplier WEG to supply suitable 11kW electric motors, VSDs and programming software. They developed an inverter-based function that corrects the cart’s stability automatically and keeps it moving smoothly. The system also recovers braking energy. The inverter controls the speed of the elevator as its descends, feeding energy back as a DC bus voltage, which needs to be dissipated in a brake resistor or burned off as heat. The original brake resistor was not large enough, and could have led to overheating. Technidrive up-sized the braking resistors and added thermal protection to avoid this risk. Since the Dubai project, the technology has also been applied to a similar installation in Dublin. Further projects are in the pipeline, including installations in Amsterdam and London. n An Irish specialist in automated storage systems is using inverters to control vertical lifts to compensate for wide variations in temperatures experienced in a Dubai installation. Inverter functions are helping to compensate for changes in temperature and weight for the Dubai automated storage installation – Birmingham The NEC 5-7 April 2022 AND K144 ST See us at: n BUILDING SERVICES