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STAYING ALIVE WITH MEDICAL ELECTRONICS

Posted by Holger Urban

Improve the reliability and functionality of medical electronic devices with EMC/EMI filtering concepts

Due to increasing demand for medical electronic devices, development in this sector is evolving fast. For example, in imaging diagnostics applications the resolution level is continuously increasing to provide greater detail and allowing more accurate diagnosis in cases previously not possible.

To ensure an enhanced level of detail, it is necessary to create an environment where EMC (electromagnetic compatibility) and EMI (electromagnetic interference) do not interfere with the operation of medical electronic systems. Even in harsh environments where radiation and very high disturbances are present, like around MRI or X-Ray systems, the imaging device must provide reliable and noise-free data. 

Covering Standards

IEC60601            Medical electrical equipment

  • Part 1: General requirements for basic safety and essential performance
  • Part 1-2: General requirements for basic safety and essential performance – Collateral Standard: Electromagnetic disturbances – Requirements and tests

 

EN 55011:2009    
  • Indus­trial, sci­en­tific and med­ical equip­ment– Radio-frequency dis­tur­bance char­ac­ter­is­tics
  • Lim­its and meth­ods of mea­sure­ment 

Considering medical standards restrict the ground leakage current in medical electrical equipment, the overall capacitance to ground needs to be reduced or eliminated in such products. This means EMC/EMI filters designed for medical applications often do not have any capacitors to ground which would reduce the performance of the filter.  As a result, high performance medical filters require additional inductance fitting perfectly to the system in order to cancel out the common mode noise.

Schaffner can provide customer specific solutions for this environment, where for example the noisy part of the device is attached to the rest via a filter and all other parts are decoupled from the filter circuit and load. In the example shown below the performance was met with dual stage inductors, reduced leakage current, C14 inlet and cable outlets splitting up monitor and load. With this design the filter fits perfectly in the environment.

With this approach MRI systems using Schaffner filters were released for usage in Charité Berlin, which is one of the most popular hospitals in Germany, with excellent international reputation for research.

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Please contact our local sales office to find out how to shape electrical power in your medical electronics.

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