4 Tips for Choosing a Medical-Grade Power Supply

When it comes to PSUs, choosing between manufacturers could be like comparing apples to oranges. If you need a medical-grade power supply, there are several things you need to consider, including your physical requirements, compliance requirements, and customization needs. Before you choose a PSU for your PC-powered medical device, we have four quick tips to start you off on the right foot. 

Be clear on your physical requirements 

What cables do you need? 

The output cables for your medical-grade power supply should fit your device, not the other way around. When you’re selecting a PSU, you’ll want to go with a company that can accommodate the output cables you need without worrying about having to slow down for design modifications. Pay attention to what standard cables a manufacturer offers, as well as whether they can provide customization – more on that next. 

 RAM Technologies offers seven standard output cables in a variety of lengths: 

  • 4-Pin ATX + 12V
  • 12 + 4-Pin PCle 12VHPWR Cable
  • Dual SATA Connectors Cable
  • 20 + 4-Pin ATX Main Power Cable
  • 6 + 2-Pin PCle Power Cable 
  • Dual 4-Pin Connectors Peripheral Cable
  • 8-Pin EPS 12V Power Cable 

What size should your medical PSU be? 

When you’re looking at sizes for your power supply, you’ll want to think about two things: The space you have available and the wattage needed for your PC medical device. 

Here’s a general rule of thumb: If you’re building a small form factor device, you’ll want a small form factor power supply – an SFX supply. Otherwise, you can get an ATX PSU, which comes with more choices for wattage. We currently offer two wattage options for our SFX – 175 and 650. However, our ATX medical-grade power supplies come in 230, 280, 310, 400, 600, and 800 watts. Your overall build size is mostly going to determine the size of your PSU.

Balance wattage with efficiency and reliability 

That being said, you need to be mindful of the actual wattage you need. The overwhelming tendency from manufacturers involves giving a higher wattage than is necessary – they might say they need 350 watts of power, but actually only need 250. We’ve done testing on these claims and have found these patterns across devices. 

The best way to figure out what wattage actually makes sense for your device is to have a conversation with the company making the PSUs. They should be able to advise the proper wattage needed, even if it isn’t the maximum listed. We’re happy to help our clients navigate recommendations to find the wattage that properly meets their requirements.

Keep customization in mind 

If a standard output cable isn’t going to cut it, you’ll need to go the route of customization. This may involve a custom length or a custom output. 

Your best bet is going with a manufacturer that makes medical-grade power supplies to order. While RAM Technologies offers a wide range of standard output harnesses, we can also customize some for short-run orders. Most of the units we produce have “non-standard” output harnesses, so we have ample experience customizing cabling to fit our clients’ needs. 

Customization considerations are especially important if you need something specific and you’re not sure whether the manufacturer can produce it. For instance, most companies don’t accommodate 12-volt and 5-volt barrel jacks, but these are two requests that we have received lately and can fulfill. 

We can also offer custom lengths for cables. While most of our cables have 3 or 4 standard length variations, we can also meet needs that fall outside of what is listed on the form. To determine whether you need a custom length, keep in mind how lengths are measured on our cables – we start at the exit point of the power supply and measure to the base of the connector housing, giving a length tolerance of +/- one inch. 

Choosing a company that makes custom cable solutions part of their offerings instead of an added bonus means you’ll be able to get exactly what you need without compromise. 

Understand your compliance requirements 

Of course, none of these considerations matter if you’re not mindful of compliance. When you’re working on a device, the type of medical-grade power supply you pick has to be compliant according to how your device will be used. 

Based on how much intended contact your device will have on patients, EN 60601-1 will assign an Applied Part classification. There are three different Applied Parts types: 

Type B Applied Parts 

The least potential risk comes with the Type B (Body) classification, which also has the least stringent protection guidelines. If a device is operating around the vicinity of a body but not attached to the patient or not normally conductive, they’d fall under this category. Some examples include MRI scanners, X-ray machines, and hospital beds. Usually, the Type B Applied Parts have at least one Means of Patient Protection (1 x MOPP) equivalent separating the part from the patient. 

Type BF Applied Parts 

Type BF (Body Floating) Applied Parts are one of two “floating” types, which are intended to make direct contact electrically with patients. This direct contact could be for either monitoring or treatment, and because of this close contact, the parts require at least two Means of Patient Protection equivalents (2 x MOPP). 

Out of the floating types, BF Applied Parts have less stringent requirements because they make direct contact but not to the heart. Ultrasound and blood pressure monitors would be considered Body Floating Applied Parts. 

Type CF Applied Parts 

The strictest protection measures come from Type CF (Cardiac Floating) Applied Parts, which are intended to make direct conductive contact with the heart. Defibrillators fall under this category. Like BF Applied Parts, they require at least 2 x MOPPs. 

Our PC-based power supplies have a standard earth leakage current to protect against electric shock, as well as sufficient insulation, abiding by 60601-1 standards and categorized as Class 1 PSUs. 

Taking the time to weigh your options and consider various factors before committing to a medical-grade power supply is the best way to save yourself time, money, and added hassle through the lifecycle of your device. If you have any questions about our PSUs, we’re only a quick message away. Contact us with questions or if you need help with the order or customization process.


RAM Technologies’ power supplies are 60601-1 certified and meet 60601-1-2 EMC standards.  Contact us for details.

More Resources:

5 Questions to Ask Before Buying a Medical Power Supply

Three Items to Look for In Your Medical Device Components

6 Things to Know About Leakage Current in Medical Devices

Leakage Current in Medical Devices

What Are Applied Parts?

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