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Power systems for patient connected equipment

We compare effective approaches for medical equipment power systems

 

Overview

• Patient connected applications place additional demands on medically approved power supplies and DC-DC converters.

• Lower power and higher power patient connected systems require different solutions. 

• For compliance, standard medically approved power supplies & DC-DC converters may be deployed individually or combined in a two-stage system.

 

In medical equipment for patient connected applications, the ‘applied parts’ are those which come into direct contact with the patient, in order to perform its function. 

Applied parts are classified according to the type of patient contact and the type or nature of the medical device in the 60601-1 suite of standards. This standard has been adopted in the major countries and regions of the world. Each classification requires different levels of protection against electric shock.

 

Applied parts classifications

Type B (Body): Is the least stringent classification, given to applied parts with are generally not conductive and may be connected to Earth. 

Type BF (Body Floating): Classifies applied parts which are electrically connected to the patient and must be floating and separated from Earth. It does not include applied parts which are in direct contact with the heart. 

Type CF (Cardiac Floating): This is the most stringent classification, given to applied parts suitable for direct cardiac and intravenous connection.

All these parts must be floating and separated from Earth. For type BF and CF medical devices, power systems are designed to provide extra isolation from the secondary output to Earth, as shown below.