Current affairs

In the design of medical electronic equipment, it is tempting to think that power supplies designed and certified to be safe in industrial applications may be equally suitable. This is not usually the case, because the risks involved are very different. Furthermore, a great deal of the electronic equipment used in hospitals, such as patient monitors, operate with very low-level signals. Medical equipment such as this tends to be more sensitive to electromagnetic interference (EMI), which also makes electromagnetic compatibility (EMC) compliance and performance a concern.

As many hospital patients are in a weak condition, exposure to even small leakage currents can have an adverse effect on their well-being. Depending on the application, the 'allowed leakage current' from the medical equipment can vary from a few µA (microamps) to a few hundred µA. Previously it was the medical equipment that was classified depending upon its application, but now it is the 'applied parts', of which there are three classifications.