Ever wondered about the BF rating on a power supply?

As a busy design engineer, you’ve probably given little thought to the meaning of the ‘BF’ rating on a power supply, particularly if you’ve never worked in the medical device arena. Even if medical is your field, you may know a BF-rated power supply is what you require, but what does it actually mean? Well, wonder no longer. Here at Mascot, we’ve got the inside track.

First of all, we should explain that the ‘rating’ is primarily about isolation – namely the isolation level of a medical patient from potential electric shock. It all becomes clearer in IEC 60601-1, the international standard that defines safety classifications for medical devices based on their level of patient contact and potential shock risk. The standard uses the term ‘Applied Part’: the part of a medical device designed for contact with a patient, such as the paddles of a defibrillator.

There are three classifications of ‘Applied Part’ that ultimately decide the level of protection required by a medical device. The highest level is Type CF (Cardiac Floating) for devices with direct electrical contact with the cardiac area. At the other end of the spectrum is Type B (Body) isolation, which provides basic protection for equipment that makes physical contact with the patient but has no electrical contact, such as MRI scanners. 

In the middle is where we come in: Type BF (Body Floating) isolation offers enhanced protection for devices making electrical contact with patients outside the cardiac area. BF-rated powers supplies are therefore suitable if you’re designing products such as ultrasound equipment, blood pressure monitors, incubators or therapy delivery systems. All require protection due to their direct patient contact through electrodes or sensors.

‘Body Floating’ might seem like an odd term, but it makes sense when you learn the definition. It refers to Applied Parts that have contact with the patient but are not earthed, meaning they are ‘floating’ with respect to electrical ground. Protection from electric shock arrives by limiting the patient leakage current to a specific maximum.

With growing pressure to cut development times without compromising safety or reliability, understanding power supply selection factors at an early phase of the design process helps you to avoid delays and ensure project success. Type BF power supplies offer proper isolation to ensure patient safety, protect the investment and maintain compliance with the appropriate standards.

At Mascot, our BF-rated (IEC 60601-1 compliant) power supplies play a major role in the development and safe use of countless medical devices. All models that form part of what we call our ‘BF-rated applications’ are free from any unacceptable risks of electrical, mechanical, thermal or functional failures, protecting both patients and operators. You’re in safe hands.