Drives&Controls & BACK TO BASICS n SPONSORED BY Is your AHU due for a health check? Many air-handling units (AHUs) in hospitals were adapted during the Covid-19 pandemic to increase ventilation rates and to maximise air changes. In some cases those temporary adjustments are still in place, leading to chronic inefficiency and unnecessary strain on equipment, as Richard Lane from Bristolbased APDS – an ABB Value Provider – explains. Working with healthcare estates teams across the UK, APDS regularly carries out surveys of hospital AHUs. Those surveys frequently reveal motors running beyond their intended operating point (max 50Hz speed ref), drives with incorrect commissioning parameters, and mechanical components preventing systems from achieving peak performance. For instance, during Covid-19, hospitals reduced airborne transmission risks by increasing ventilation rates. Often the quickest way to do this was simply to increase fan speeds. While this met the immediate operational need, many of these changes remained in place long after they were needed, leaving AHUs operating outside of their original design parameters, and putting motors into field weakening. How do we fix this? The first step is not necessarily about replacing equipment, but about assessing and understanding whether the system is operating as intended. A mechanical and electrical survey can identify issues that have developed gradually over time, but remain hidden during routine maintenance. Many AHU systems have evolved over decades, with different teams making different adjustments to keep systems running. Again, these adjustments are often made in good faith. But without a holistic view of the whole installation, inefficiencies can accumulate. A motor might be updated, yet the drive settings are kept the same. Or changes in the facility’s power factor or harmonic content are not reflected in the complete power drive system. In my experience, around 30-40% of installations will have incorrectly configured equipment – I routinely see obsolete equipment from more than 30 years ago. Motors, drives, and mechanical components should all be correctly matched to achieve expected performance. Power quality is also an important factor. Hospitals are continuously adding more and more harmonic-generating equipment, yet the electrical infrastructure often remains unchanged – and may, by now, be operating close to its limits or in bypass. Reviewing harmonic levels and ensuring mitigation strategies, such as ULH (ultra-low harmonic) drives, can improve resilience and availability, without having to upgrade cables and distribution devices. Optimising AHUs is about understanding the complete system rather than replacing individual components. As an ABB Value Provider, we‘re able to take a step back and consider systems from both an electrical and mechanical perspective, ensuring your whole AHU system gets a clean bill of health when it comes to offering peak efficiency, reliability and performance. Lamonde Automation Limited Quality Products: Expert Advice +44 (0)20 3026 2670 sales@lamonde.com | www.lamonde.com Lamonde Automation Limited Quality Products: Expert Advice Easy installation and terminals that make wiring-up simple AS EASY AS COMMANDER S CLICK, WIRE, GO
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