Table of Contents




Medical Power Supplies: IEC 60601-1


Introduction

Welcome to the CUI Product Spotlight on medical power supplies and the IEC 60601-1 medical design standards. Learn about IEC 60601-1, including an overview of its various standards, its evolution through to the latest 4th edition EMC requirements, and its impact on power supply design. This presentation will also highlight CUI's line of internal and external medical power supplies that have been certified to the IEC 60601-1 edition 3.1 safety standards for 2 x MOPP applications and 4th edition EMC requirements.

Objectives

  • Overview the IEC 60601-1 medical standards
  • Detail the evolution of IEC standards through to 4th edition
  • Discuss IEC 60601-1's global adoption around the world
  • Highlight CUI's line of IEC compliant medical power supplies

What is IEC 60601-1?


IEC 60601-1 is a series of technical standards for the safety and effectiveness of medical electrical equipment that has become a de facto requirement for bringing new medical devices to market in many countries. Deviations from the standard do exist that relate to country-specific requirements, but those standards such as Europe's (EN 60601-1) and Canada's (CSA 60601-1) are harmonized to the IEC standards. Within IEC 60601-1, there are also "collateral" standards that are denoted as IEC 60601-1-x. For example, IEC 60601-1-2 is the EMC collateral standard that forms the basis of the latest 4th edition EMC requirements.

The History of IEC 60601-1


The original IEC 60601-1 standard for medical devices was published in 1977 with the 2nd edition following 11 years later in 1988. The 2nd edition which focused on safety within the vicinity of a patient was followed by the 3rd edition in 2005 that looked at "means of protection" (MOP) both for patients and equipment operators. A substantial amendment to the 3rd edition, known as Edition 3.1, was introduced in 2012 that addressed numerous ambiguities arising from evolving medical equipment technology. Most recently, in 2014, a new version of collateral standard IEC 60601-1-2, "Electromagnetic disturbances - Requirements and tests," was published. This EMC standard provides us with what is now commonly referred to as the "4th edition."

2nd Edition Device Classifications


The 2nd edition of IEC 60601-1 established risk guidelines that applied when a device was within a 6-foot radius from the patient, referred to as the "patient vicinity." The standard further classified medical equipment into three categories. Type B (body) equipment that operates within the patient vicinity, but without patient contact. Type BF (body floating) equipment is characterized by having direct contact with the patient. Type CF (cardiac floating) equipment has direct contact with the patient's heart. Each classification had different required standards for isolation, insulation, creepage, clearance, and leakage.

  • Type "B" (Body) operates within the patient vicinity
  • Type "BF" (Body Floating) makes physical contact with the patient
  • Type "CF" (Cardiac Floating) makes physical contact with the heart

3rd Edition Device Classifications

The 3rd edition of IEC 60601-1 extended the patient focus to require an overall means of protection (MOP) that combined one or more "means of operator protection" (MOOP) and "means of patient protection" (MOPP), recognizing the potential hazards seen by each user are different. For instance, an operator has access to a control panel, while the patient may be connected via probes. An ISO 14971 Risk Analysis / Management process is then used to define one of four possible "means of protection" classifications noted below.

  • ONE MOOP: Single "Means of Operator Protection"
  • TWO MOOP: Two "Means of Operator Protection"

  • ONE MOPP: Single "Means of Patient Protection"
  • TWO MOPP: Two "Means of Patient Protection"

Comparing 3rd Edition and 2nd Edition

The changes from the 2nd to 3rd edition as they apply to power supplies were more a matter of definition than actual performance. For example, 2nd edition Type BF applications need to meet the 3rd edition's "two MOOP" and "one MOPP" requirements, and 2nd edition Type CF not only requires an IEC 60601-1 qualified supply, but must ensure an additional isolation barrier between the supply and the part that touches the patient. This is typically achieved with an isolation transformer or dc-dc converter with 8 mm creepage and double insulation as outlined in the "two MOPP" classification shown below. Regardless of edition or classification, medical devices may not exceed 500uA leakage current and must have dual fused input protection.

2nd Edition Requirements by Classification

Classification Isolation Creepage Insulation
Type B 1500 Vac 2.5 mm Basic
Type BF 3000 Vac 5 mm Double
Type CF 4000 Vac 8 mm Double

3rd Edition Requirements by Classification

Classification Isolation Creepage Insulation
One MOOP 1500 Vac 2.5 mm Basic
Two MOOP 3000 Vac 5 mm Double
One MOPP 1500 Vac 4 mm Basic
Two MOPP 4000 Vac 8 mm Double

3rd Edition - Analyzing Risk


While the performance thresholds remained largely the same, the prime objective of the 3rd edition standard was avoiding unacceptable risk in the event of failure, degraded performance, or functionality. Therefore, it required equipment developers to establish a Risk Management Process described in ISO 14971, determine acceptable levels of risk, and show that the remaining risk is acceptable. It also demanded greater interaction between the equipment manufacturer and the test laboratory, as illustrated above. This distinguishes between the criteria established by the risk analysis and the test processes used to demonstrate compliance.

IEC 60601-1 Edition 3.1


IEC 60601-1 Edition 3.1 was introduced in 2012 to address many issues identified as unclear or ambiguous in the original 3rd edition standard that was released in 2005. Edition 3.1 includes almost 500 changes and clarifications across a spectrum of subjects, including essential performance, risk management, mechanical testing, temperature testing, and humidity testing. The amended standard also defines several new specifications for mechanical and electrical hazards.

4th Edition - IEC 60601-1-2

Due to the growing use of devices like smart phones, laptops, and tablets that communicate wirelessly, the new IEC 60601-1-2 collateral standard was introduced to address a reciprocal concern about electromagnetic compatibility (EMC) affecting both the medical device in question and other devices in the vicinity. In the past, it may have been possible to exclude these sources of interference from sensitive medical environments, such as hospitals, but with more and more medical equipment now intended to operate in home and other environments, EMC concerns had to be taken into account. These "intended use environments" introduced in the 4th edition are specifically defined in three categories: professional healthcare facilities, home healthcare, and "special" environments. The details of these intended use environments are further outlined below.

Intended Use Envrionments

  • Professional healthcare facilities with attending medical staff such as hospitals, intensive care units, and dental offices
  • Home healthcare defined in collateral standard IEC 60601-1-11, as dwelling places where patients live or are present (excluding professional healthcare facilities). Here equipment will be used by non-specialist users and must be tolerant of poor electrical supplies
  • "Special" environments include high levels of electromagnetic disturbance (e.g. due to industrial machinery), or where high-power medical equipment might be used (e.g. radio-therapy equipment)

The Adoption of IEC 60601-1 Worldwide

Broadly, it is expected that manufacturers will adopt newer standards well before mandatory transition dates. Indeed, in the United States, the FDA has already accepted the 4th edition and prefers products to be tested to that standard. The US and Canada currently require compliance to edition 3.1 and are officially targeting a December 31, 2018 implementation date for 4th edition to harmonize with the European Union's adoption timeline. Both new products and pre-existing products that are subject to a design change must comply with the 4th edition standard after the transition date. However, adoption of the various revisions of IEC 60601-1 around the world is a mixed picture, with transition to the 4th edition being unclear. This means products shipping internationally may require designs meeting more than one revision of the IEC standards or multiple versions of the same design in order to comply.

Europe

  • Compliant with edition 3.1 as of December 31, 2017
  • Adoption of 4th edition set for December 31, 2018

North America

  • US and Canada currently in compliance with edition 3.1
  • December 31, 2018 4th edition implementation date harmonized with EU

Around the World

  • Regional adoption of IEC 60601-1 remains mixed with 4th edition adoption timelines unclear

CUI's Internal Medical Power Supplies

CUI's line of internal medical power supplies ranging from 20 W to 550 W offers class leading power density and energy efficiency with the majority of models certified to the IEC 60601-1 edition 3.1 safety standards for 2 x MOPP applications and 4th edition EMC requirements. Housed in compact, open frame or metal enclosed packages, these embedded ac-dc medical power supplies feature power densities as high as 30 W/in3, no-load power consumption as low as 0.3 W, and efficiency up to 94%.

VMS Series

  • 20 W to 550 W power ratings
  • 60601-1 certified for 2 x MOPP applications
  • Most models comply with 4th edition EMC standard
  • Power densities as high as 30 W/in3
  • No load power consumption as low as 0.3 W
  • Efficiency up to 94%
  • Open frame and metal enclosed packages
  • Industry standard 2 x 4 and 3 x 5 inch packages available
  • Compact, low profile options

CUI's External Medical Power Supplies

CUI's line of external medical power supplies ranging from 6 W to 250 W are all certified to the IEC 60601-1 edition 3.1 safety standards for 2 x MOPP applications and 4th edition EMC requirements. The line includes fixed blade, interchangeable blade, and desktop models featuring no-load power consumption as low as 0.075 W, high efficiency, and a universal input voltage range. The majority of models also feature class II construction and come standard with over voltage, over current, and short circuit protections.

SWM, SDM, EMMA & ETMA Series

  • 6 W to 250 W power ratings
  • IEC 60601-1 4th edition certified
  • 2 X MOPP compliant
  • No-load power consumption as low as 0.075 W
  • Wall plug, multi-blade, and desktop models
  • Horizontal and vertical wall mount orientations
  • Universal input voltage range
  • Over voltage, over current, and short circuit protections

Applications

CUI's internal and external medical power supplies can be employed across a wide range of applications, including diagnostic equipment, medical monitoring devices, laboratory instruments, and home patient and dental care.

Diagnostic Equipment

Medical imaging, CT scanners, ultrasound, blood analysis

Medical Monitoring

Blood pressure monitor, ECG, EEG

Laboratory

Chemical analysis, lab automation

Home Patient Care

Medical bed, CPAP, infusion pump

Dental

Dental chair, dental LCD display, oral care equipment

Summary

The IEC 60601-1 standard is complex and simply shipping a medical device with basic documentation to a certification lab is no longer adequate. Understanding the many regional variations of the standard as well as its collateral and particular standards can become a major challenge. This is why CUI offers a comprehensive line of embedded and external medical power supplies ranging from 6 W to 550 W that have been certified to IEC 60601-1 edition 3.1 2 x MOPP safety standards and 4th edition EMC requirements in order to simplify the compliance process for medical device designers.

 
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