Tutorial: How to select power supplies for medical equipment

Author : David Buck | Market Development Manager | TDK-Lambda

01 January 2021

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As David Buck, Market Development Manager at power supply manufacturer, TDK-Lambda explains here, the selection of a medical power supply should be approached with great care, following recent updates to medical safety standards.

The full version of this tutorial was originally featured in the January 2021 issue of EPDT magazine [read the digital issue]. Sign up to receive your own copy each month.

IEC 60601-1 has added risk reduction, in light of the increasing number of devices now being deployed in home healthcare applications. Operating in a domestic residence presents additional challenges to that of the sterile, benign environment found in a hospital.

Today, switch-mode power supplies are deployed in a vast array of medical equipment, ranging from large MRI (magnetic resonance imaging), PET (positron emission tomography) and CT (computerised tomography) scanners to smaller patient monitors and analysers. In addition, robotic surgical equipment and automated pharmaceutical dispensers are now frequently used in hospitals. The trend in medical equipment has followed the technology of most electronics, requiring smaller, lighter in weight, more efficient and more reliable products, with an intensive drive for cost reduction.

The safety standards for medical equipment vary widely depending upon the application, proximity to patients and operators, and the location and environment of the equipment. For home healthcare applications, for example, only Class II (no earth ground connection) power supplies are permitted, as the integrity of the earth connection cannot be guaranteed. In the design of electronic medical equipment, there is one consideration which takes precedence over all others – the safety of the patient and the operator. In some cases, it might be tempting to think that power supplies that have been designed and certified to be safe in industrial applications might be equally suitable for use in medical equipment. But this is not usually the case, because the risks involved are very different.

The requirements for EMC (electromagnetic compatibility) have been toughened, following trends in other industries, like commercial air travel, with the now widespread use of mobile phones, tablets and gaming. Much of the electronic equipment used in hospitals, such as patient monitors and digital scanners, operate with very low-level signals. Medical equipment like this tends to be more sensitive to electromagnetic interference (EMI) than most of the equipment used in industry.

Read the full article in EPDT's January 2021 issue...


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