AC/DC Power Supply Selection Guide for Medical Imaging Equipment

Designing power into medical imaging equipment is one of the more demanding integration challenges an engineer will face. The regulatory requirements are strict, the electronics are noise sensitive, and the consequences of getting it wrong extend well beyond a failed test.

At TRC Electronics, we work with design engineers across CT, X-ray, MRI, and ultrasound platforms, and the same pattern comes up repeatedly. System behavior becomes inconsistent only after full assembly. Signal artifacts, calibration drift, or baseline instability appear without a clear single fault source, and the initial focus goes to firmware before power integrity gets identified as the contributor.

Selecting the right medical AC/DC power supply early in the design process is a decision that determines patient safety, regulatory approval, and system performance. Meeting IEC 60601-1, ANSI/AAMI ES60601-1, EN 60601-1-2:2015 (4th edition), and EN55032 Class B, are not constraints you address late. In high-resolution medical imaging equipment operating in the microvolt range, they need to be part of the specification before layout begins. 

In this blog we will walk through the key integration challenges and show how the Delta IMA Series addresses them directly, including low leakage current performance, EMI compliance, acoustic noise, and expected service life.

Integration Challenges in Medical Imaging Equipment

AC/DC power supply selection in medical imaging equipment introduces constraints that are often not isolated to electrical performance alone. Several system level factors tend to cause challenges during integration.

EMI Compliance and Signal Integrity in Medical Imaging Equipment

Detector front ends in CT, MRI, and ultrasound platforms operate in the microvolt to millivolt range. At that signal level, a switching AC/DC power supply that exceeds EN55032 Class B limits under IEC 60601-1-2 is not just an EMC compliance problem. High frequency noise couples directly into the analog signal path and the effects are rarely obvious.

What we see in the field is not a hard electrical fault. It shows up as ghost artifacts, baseline instability, or what looks like sensor drift. The assumption is almost always firmware or calibration. By the time power integrity gets identified, significant debug time has already been spent in the wrong place.

The noise has to be addressed at the source. High attenuation filtering and low emission switching topologies keep the PSU from becoming a variable in system level EMC testing, allowing the analog front end to perform to its actual design capability.

Meeting EMI at the system level may also require additional EMI filters at the AC input. TRC Electronics carries a range of medical EMI filters from Delta Electronics and other manufacturers to support full system compliance.

Figure 1: Delta IMA Series  EMI Compliance For Medical Imaging Equipment

IEC 60601-1 Medical Ratings for Imaging Equipment

Compliance with IEC 60601-1 and ANSI/AAMI ES60601-1 is a mandatory safety requirement for any medical imaging equipment entering a clinical environment. Medical imaging equipment typically requires BF rated equipment, meaning the applied parts are body floating and suitable for direct patient contact but not cardiac applications. Where ECG gating or cardiac monitoring is integrated into the imaging workflow, CF ratings may apply to those specific circuits.

For medical imaging equipment where electronics are adjacent to the patient, the AC/DC power supply must provide specific isolation barriers meeting 2xMOPP (Two Independent Means of Patient Protection). This level of galvanic isolation is essential to protect both the patient and the sensitive imaging hardware from fault conditions or transient surge events, and it is mandatory at the component selection stage rather than something that can be addressed at the system level after the fact.

Figure 2: Delta IMA Series Safety And Isolation

Designed to support Type B and BF Applied Part end product requirements

How to Manage Leakage Current in Medical Imaging Equipment

IEC 60601-1 and ANSI/AAMI ES60601-1 define strict limits by applied part classification. BF rated equipment is limited to 500µA under normal conditions. Leakage current is a system level accumulation. This means that multiple AC/DC power supplies contribute to the total on the DC bus, and when one supply consumes a large portion of the allowable budget, downstream flexibility is reduced significantly.

Figure 3: Delta IMA Series Leakage Current At 264VAC (Worst Case, High Line)

All models meet IEC 60601-1 BF leakage current limits per manufacturer datasheet

Acoustic Noise in Medical Imaging Equipment

Medical imaging equipment operates in clinical environments where noise matters. Sealed enclosures and hygiene requirements mean thermal management depends heavily on forced-air cooling, and fan noise in those conditions is not trivial.

Beyond the acoustic impact, mechanical vibration from fan systems can propagate through the chassis and in some configurations couples into sensitive analog components or detector assemblies, introducing low level instability that is difficult to trace back to the source.

Keeping fan speed low and turning fans off when the system does not need them is the most direct way to manage both issues.

Figure 4: Delta IMA Series Acoustic Noise

Tested at 100Vac, 100% load, 30°C ambient, 1m distance

Reliability and Expected Service Life for Medical Imaging Equipment

Medical imaging equipment is expected to operate continuously over long service lifetimes, often exceeding a decade. Unplanned downtime in a clinical environment will affect patient throughput and in some cases access to critical diagnostics.

MTBF is a useful reference point during component selection, but it is not the complete picture. A single power supply failure can disable multiple subsystems simultaneously, making it a high consequence point in overall system availability.

The more important metric is the expected life at operating temperature. A supply with an impressive MTBF figure but limited capacitor life at elevated temperatures will not deliver the service lifetime the system demands. Engineers should be asking for expected life data at actual operating conditions, not just the headline MTBF number.

Figure 5: Delta IMA Series Reliability And Life Expectancy

Life expectancy figures reflect actual operating conditions, not just statistical MTBF averages

Summary

In medical imaging equipment, the power supply is usually one of the first things that gets looked at when something goes wrong. The problem is that power integrity issues rarely present as a clean electrical fault. By the time the PSU gets cleared and the debug focus shifts to firmware or sensor calibration, debug time has already been lost.

Selecting a medical AC/DC power supply that meets IEC 60601-1, carries BF applied part classification, complies with EN55032 Class B and is designed for the actual service life of the equipment is not something to revisit at integration. It needs to be in the specification from the start. The Delta IMA Series addresses each of these requirements directly. 

If you are specifying power for medical imaging or any other medical device, give us a call at 888-612-9514. Our team of power specialists is ready to help you select the right medical power supply.

Reference:

Strategic Business Trends. (2025, October 9). Medical Power Supply Products in the Real World: 5 Uses You'll Actually See. LinkedIn. https://www.linkedin.com/pulse/medical-power-supply-products-real-world-5-uses-dfvcc.