Feature: Medical
Due to the lack of Y-caps, usually located between the active conductors and earth, the common-mode performance is only based on the inductor and the core material used
Medical devices require exact EMC filters By Holger Urban,
Product Manager, Schaffner
E
lectromagnetic compatibility (EMC) filters play an important role in ensuring reliable operation of medical equipment. Te number of devices per hospital or operating theatre is continually increasing, and interoperability plays a major role for life-sustaining equipment.
EMC-compliant design begins with the power entry to the
electronic device. In most equipment, a combination of an IEC connector with embedded EMC filter is the most economical solution. Fully-isolated power supplies need filters that support Class
II medical devices, and feature enhanced creepage distances in the filter and insulation from the rest of the system. Combining
26 March 2021
www.electronicsworld.co.uk
Chassis-mounted EMC filter
a plastic housing with an IEC C18 inlet (without earth pin) gives the medical equipment developer the required freedom to start an isolated design right away. Te EMC requirements for diagnostic equipment are given
by IEC/EN 60601, which refers to the limit values of the CISPR standards. Most electrical medical devices are categorised using the generic standards, sorted into classes according to their use: i.e., in the home, doctor’s surgery (B), or hospitals with separated AC mains (A). Emissions must comply with the limits of CISPR 11: For simple electrical components, the reference is CISPR 14, while lighting facilities refer to CISPR 15, and IT systems use CISPR 22. In addition to the usual standards, Schaffner follows UL60939-3, IEC 60939-3, CAS and CQC, and for the FN9274 EMC filters, medical Class II compliance is taken into account. Te company’s IEC safety certificate shows compatibility with certain application- specific standards including 2MOPP compliance, with other compliances listed in its products’ data sheet.
Medical electrical compliance Syringe pumps, medical ventilators, lasers or patient-monitoring devices with parts in direct physical or electrical contact with patients are defined as medical devices (MD). Here, operating at
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