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Understanding Applied Parts and Leakage Current in Medical Power Supplies

Medical device designers must go to great lengths to ensure human safety. Medical equipment can pose hazards to patients in a weakened state as well as to personnel operating the devices. Accordingly, strict standards exist to help guarantee global compliance. For power supplies, one of the most important ones is IEC 60601-1, which covers essential safety-related specifications and values, such as isolation voltage and leakage current requirements that must be met to protect people from electrical shock.

Understanding Applied Parts and Leakage Current in Medical Power Supplies

To mitigate the leakage current that can affect patients, IEC 60601-1 classifies applied parts of medical equipment based on their proximity to or contact with the patient. While power supplies are not medical devices themselves, IEC 60601-1 establishes leakage current levels and isolation requirements for power supplies used in medical devices. The applied parts and leakage limits for each are as follows:

  • Type B (Body). These parts operate near the patient. They are not intended to pass current to a patient and can be connected to ground. Allowable leakage current is 100 µA under normal conditions; 500 µA single-fault.
  • Type BF (Body Floating). These parts are intended to deliver energy to or from the patient and do not connect with ground. Allowable leakage current is 100 µA under normal conditions; 500 µA single-fault.
  • Type CF (Cardiac Floating). Type CF parts are intended to deliver energy to or from the patient for direct contact with the heart or bloodstream. Allowable leakage current is 10 µA under normal conditions; 50 µA single-fault.

Power supplies in Types B, BF and CF-rated B-rated parts require 4,000V AC input to output isolation. In addition, power supplies must satisfy these isolation requirements: Type B: 1,500V AC input to ground isolation and 500V AC output to ground isolation. Types BF and CF require 1,500V AC input to ground isolation and 1,500V AC output to ground isolation. To learn more about isolation, check out this blog post.

IEC 60601-1-Compliant Power Supplies Reduce Patient Safety Risks

When selecting a power supply for a medical device, make sure it complies with IEC 60601-1. Medical power supply manufacturers will also indicate whether a power supply meets Type B, Type BF or Type CF criteria. For designs requiring 240W of output power, our PFMUI Series of universal input switching power supplies are designed with patient safety in mind. Providing 4,000V AC input to output 2xMOPP insulation, these devices meet the UL/IEC/EN 60601-1 edition 3.1 safety standard and are suitable for Type BF applications when implemented into an appropriate system.

Additional features include high efficiency, 0.5W no-load input power and a PFC function of >0.9. PFMUI power supplies in the following package types:

  • Open type (PFMUIO240)
  • U chassis type (PFMUIT240)
  • Enclosed type (PFMUIE240)
  • DIN rail type (PFMUIE240-DN)

Look for Power Supplies That Meet IEC 60601-1 Standards

Because medical devices can potentially make patients susceptible to shock and safety risks, medical power supplies must meet stringent IEC 60601-1 requirements. Our PFMUI power supplies for BF-type applications satisfy IEC 60601-1 and other standards while providing medical device designers a choice in packaging options to suit their system’s needs.

Find out more information about our PFMUI medical power supplies and other switching power supplies.