Choosing a product certified to IEC/EN 60601-1 is a safe and reliable option when specifying a built-in AC/DC power supply for medical applications. However, some issues still need to be considered, such as the requirements for external fuses and EMI filtering. This article will explore these requirements and introduce some available power supplies to assist with final product certification.
The demand for power supplies in medical applications is substantial, especially during global health crises. With the increasing need for ventilators, analyzers, and life support equipment, product designers must select power supplies that meet the latest medical standard IEC 60601-1:2005 and its ancillary documents. Furthermore, there are national standards: the US ANSI/AAMI ES 60601-1:2005, the European EN 60601-1:2006, and other global standards, each with its own local regulations. On August 20, 2020, IEC 60601-1 Revision 2 (IEC 60601-1:2005 + A1:2012 + A2:2020) was officially released. The revision updates outdated standard references, aligns more closely with IEC 62368-1 (Safety Requirements for Audio/Video, Information and Communication Technology Equipment), corrects errors, and provides detailed specifications. The ancillary electromagnetic interference standard IEC 60601-1-2 is currently in its fourth edition.
Uses built-in medical-grade power supply
Medical devices consuming over 100W typically have built-in AC power supplies instead of using external adapters. Product designers have an obligation to consider this, as current devices contain unsafe voltages and electrical energy. While built-in power supplies may be medically certified, the entire final product must still comply with electrical safety and EMC requirements, including labeling, connectors, fuses, and internal AC power wiring. For example, if the device's AC power cable has a connector, it must use a dual fuse for both live and neutral wires.
There are several considerations when adding an EMI filter between the built-in power supply and external connections. The medical electromagnetic compatibility standard IEC 60601-1-2, fourth edition, is more complex than previous versions, and care must be taken to ensure that the mains leakage current does not exceed the levels specified in the standard when using additional EMI filters. Even if the filter claims to meet medical standards to a certain extent, the combined leakage current from the built-in power supply may exceed permissible limits. Ideally, the built-in AC/DC power supply should be connected directly to the medical device's power socket, use dual fuses, and require no EMI filtering. If the power supply has the highest level of medical-grade certification and excellent EMC performance, then there is a high degree of confidence that the safety and EMC performance of the end product fully meet the requirements.
In some medical applications, non-medical power supplies can be used, but the following considerations apply. For example, power supplies certified to standard IEC 62368-1 have enhanced mains isolation and are considered to have double protection (2 MOOP), making them suitable for laboratory testing environments where there is no patient contact. However, the fourth edition of electromagnetic interference requirements also applies to operator environments, so many non-medical power supplies do not meet the requirements. Even if the same power supply is used, assuming its 2 MOOP equals 1 MOPP, there is still a risk, and the application must be assessed for overvoltage, contamination levels, altitude, and the medical environment in which the product may be used. The risk assessment will indicate which environment is relevant, such as professional facilities, home healthcare, or special environments, such as in ambulances where RF communication systems emit high levels of electromagnetic radiation.
Safety is the only option.
A safe solution is to use a power supply with 2MOPP certification that provides appropriate leakage current and EMC performance for the target application, such as RECOM's RACM230-G, RACM550-G, and the recently released RACM-1200V (Figure 1).
Figure 1: The RACMxx series power supplies with medical certification, with rated power from left to right: 230W, 550W, and 1200W.
These power supplies are suitable for medical-grade internal applications, with forced air cooling ratings of 230W, 550W, and 1200W. They can all provide continuous rated power of 160W, 300W, and 800W when using baseplate cooling without fan intervention, eliminating the need for fans, which are often unacceptable in medical environments. Each power supply type has a 2MOPP/250VAC rating, a maximum operating altitude of 5000m, and leakage current suitable for patient connections in Type B (body, grounded) (RACM230) and Type B/BF (body/body floating) (RACM550/1200) models, which are in direct contact with the patient. The RACM230 complies with IEC 60101-1-2, Edition 3, electromagnetic interference requirements, while the RACM550/1200 is certified to Edition 4.
The RACM550-G and RACM1200-V products feature a +5V 1A/1.2A isolated standby output, and all models are equipped with intelligent fan outputs, allowing for system fan cooling if needed. These products utilize industry-standard form factors: RACM230-G is 4” x 2”, RACM550-G is 5” x 3”, and RACM1200-V is 9” x 3.8”, offering leading power density. The newly introduced RACM1200-V offers single-channel outputs of 24V, 36V, or 48V, operates at over 95% efficiency, and meets EuP Lot 6 standby power requirements.
The safety configuration for each RECOM power supply is shown in Figure 2.
Figure 2: Safety barrier of RACM230/550/1200 series
The RACM1200-V also features a PMBus™ interface for control and monitoring within medical products. If this interface is an external connection and is classified as a SIP/SOP (Signal Input/Output Section), it must be isolated with a dual patient protection (2MOPP) level. Alternatively, for lower power applications, a medical-certified 2MOPP DC/DC converter (Figure 3) can be inserted between the power supply and the patient connection to ensure lower leakage current. Suitable DC/DC converters include RECOM's REMxx series, rated from 1W to 30W.
Figure 3: SIP/SOP connections may require additional isolation levels.
With the introduction of the latest version of the safety standard IEC 60601, commercial or AV/IT-grade AC/DC power supplies for medical devices with "additional" modifications and/or usage restrictions are no longer widely applicable. Considering product development, testing facility costs, and time-to-market, medically certified power supplies, such as RECOM's RACM series, are the best and most economical solution for a smoother certification process and wider product availability.
RECOM products are supported by a global distributor network, helping customers integrate AC/DC power supplies into medical products with the fastest design cycle and providing technical support and services.
