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From idea to product - Real modified standard service for medical power supplies requires more than changing the plugs

Published: 2 March 2019 - Sarah Mead

By Teresa Fernandez Gomez, sales manager Europe, EOS Power India

In medical technology applications, the space for electronics is very limited. At the same time, special approvals and strict safety standards apply. This means that device engineers in this field need an efficient standard power supply, which meets the highest technological standards - products that benefit system designers. To support these needs, leading-edge power supply producer EOS Power, focuses on the development of medical power supplies, which are optimised to deliver leading efficiencies and densities, while also addressing the stringent quality, regulatory, and product life cycle requirements inherent in the medical industry. In doing so, the power supplier enables his customers to meet the growing demand for smaller, more efficient medical products.

EOS Power delivers medical power supplies for various kinds of systems, i.e.

  • Diagnostics - Medical imaging, CT scanning, ultrasound, blood analysis
  • Monitoring - Blood pressure monitoring, ECG, EEG
  • Laboratory - Chemical analysis, lab automation
  • Home Patient Care - Medical bed, CPAP, infusion pump
  • Dental - Dental chair, dental LCD display, oral care equipment

Whether these units are conduction-cooled via a baseplate, convection or fan-cooled: they enable system designers to manage heat generated in the system effectively, thereby increasing product lifetime for medical applications. Reliable products like those from EOS require unique evaluation techniques and base in a collaboration with the component´s manufacturers to establish a manufacturing and designing style that enables the components to work longer.

EOS’ MWLP75 and MWLP120, can utilise 75W & 120W of output power respectively from a dense 2x3” package. The series should be of interest for medical requirements where it space at a premium, but power not reduced and cost not compromised.

For medical systems, the MWLP75W & 120W variants take care of everything. Both are dual fused and approved to the latest editions of EN/IEC/ANSI/AAMI 60601-1 medical safety standard. They are also suitable for BF rated applications, provide 2xMOPP and are fully compliant with the IEC 60601-1-2: 2014 Edition 4 immunity update. In addition, the MWLP75W & 120W is designed to ensure it can be used across the globe in a variety of environmental situations without performance variation.

The MWLP75 and MWLP120 series is now successfully tested for 4KV surge (IEC61000-4-5, Level 4) along with our other series MWLP350, with no change in the product design.

MVLT Series product is the most popular product series from VLT Series family for EOS. Particularly MVLT60 series is being used by many Medical customer example, PHYSIO CONTROL and ROCHE MEDICAL among others.

All EOS Power supplies are RoHS 2 compliant as per available data and certificates from manufacturers and suppliers. We have initiated the process of collecting RoHS 3 certificates. The RoHS 3 directive is going to be mandatory from July 2019; and we will surely complete all the related activities well before that.

Modification examples

As much important for the success of the open frame power supply integration in many medical technology projects is the ability to modify the power supply without changing the technical values. The main topics often are connectors, EMC and ultimately also the load profile.

There are various Modifications, a smart and well-integrated company like EOS Power can realise for its customers. Let’s have a look at a CT scanning system. The customer was developing a CT scanning System that required an uncommon power solution to enable small size and mobility- the power solution needed to run on an AC Connection and from internal batteries to allow mobility.

Another customer was designing their next generation Tomography System and was far along in their design with a brand-name power supply manufacturer, when they realised they would need some modifications to the supply. The brand-name p/s provided Universal AC Input with Dual outputs. The primary change needed, was to move all connections to one side of the supply and use quick-disconnect type of connectors.

EOS quickly assessed the requirement and delivered ten prototypes, while the brand-name manufacturer was still defining their NRE Charges of more than $30,000. EOS power solution provided substantial advantages including a reduced production pricing and lead times as well.

Eventually, the customer received a simple power solution, modified to fit their specific application requirements. He benefits from a higher level of service, an improved power solution with substantially reduced design costs, production costs and manufacturing lead times.

More than just new plugs

Very unusual Modifications had been done, when designing the Loewenstein respiratory devices prisma VENT30/40 and the ventilator VENTIlogic LS, both of which were equipped with the older EOS power supply MWLT 150. The look back at this project shows what challenges lie ahead for the pre-certified power supplies competing for being used in Medical Devices. While a quite usual modification is changing the connectors - users can usually choose between screw terminals and plug-in terminals at the output - for one Loewenstein respiratory system’s power module, a special output connector was selected. This enabled them to work with the same wiring harness in all his devices. In addition, the position holes as well as the cross-section of the fastening and the circuit board for the ventilator were individually adapted in many small steps. Even the shrink tubing for fire protection reasons has been changed.

So what is getting clear: Announcing modification abilities, many device producers just consider topics like new plugs or cables. But the usual standard modifications from plug to output voltage very often come out to be insufficient. To meet Loewestein requirements eventually even component parts were added and modified, to meet the voltage and load profiles needed. Afterwards intense test series were run jointly in Hamburg and Mumbai and once a customer-specific NTC for temperature monitoring and fan control due to ventilation phases were integrated; the Ventilogic LS even used other MOSFETS in the PFC stage, which tolerate particularly higher voltages. Later, also the 2xY2 capacitors were adapted to improve the load profiles and EMC performance. 

Process integration in the background

And now we get to the core of EOS’ ability to modify – which is the will to the integration of services and design processes behind the scene. Since 2016, Loewenstein has been working with special barcode stickers in the areas of incoming goods, production, quality assurance and batch control, which are required in three different versions on the components in their production in Hamburg. These labels, including barcodes and peel-off stickers, are already applied and registered by the manufacturer in Mumbai. In India, precautions have also been taken to comply with customer-specific ESD packaging regulations with the support of its distributor CODICO, who is based in Austria. For Loewenstein, distributor CODICO still carries out complete serial number tracking and customer-specific packaging labelling, while EOS in India are taking care of additional DoC tests.

Furthermore, suppliers can support customers with documentation requirements. Since an essential part of the risk analysis, in the sense of EN60601, is the handling of critical components, assembly variants and second-, third- and fourth-source components often drive welding beads on the forehead of medical technology designers. An open approach to the parts list enabled this customer to real in-depth customer-specific adaptations.

Perfect conditions for High Mix Low Volume

Why can all this been done? All EOS power supplies are produced centrally at EOS Power in Mumbai and the production systems are deliberately kept flexible and adjusted to high-mix and various modifications. Even quantities of only a few thousand identical components per year can be cost-effectively produced there. The EOS high-mix-low-volume "pick and place" systems can handle different types of printed circuit boards and components. It also can easily be handled, when the designs have different connectors to match the compact design of the power supplies; the equipment ensures reliable placement of larger components as well as the placement of resistors and very small capacitors - as well as the accurate placement of a wide range of SMT components through to fine pitch components such as ICs, QFN packages and BGAs.

This manufacturing facility has received numerous awards for quality and manufacturing processes from renowned bodies such as Dun & Bradstreet, Frost & Sullivan and Elcina. Many customers audited the EOS production in India yet. And last but not least, according to Wolfram Heinrich, leading product design manager from Loewenstein, it of course is also important that the price - also of the higher Watt segment EOS open frame power supplies – throughout all changes and modifications kept being “very reasonable”.

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