New safety standard IEC 62368-1 replacing IEC 60950-1
All our power supply Adapter complies with new LVD Standard EN 62368-1.
Within just a quarter or so, manufacturers of ICT and AV equipment will have to conform to a new standard for product safety, the IEC 62368-1.
The date of withdrawal (DoW) for the outgoing standards IEC 60950-1 and IEC 60065 is December 20, 2020.
There are a few things one should have in mind, not least when dealing with power supplies, as Part 1 of the standard deals with safety requirements. IEC 62368-1 was written using hazard-based concepts, with energy sources and their potentially harmful effects as focal design considerations.
Historically, ICT (Information and Communication Technology) and AV (Audio/Visual) equipment have been regarded as separate products and markets, and as one takes a look back, it used to be pretty easy to differ the two. Today, these technologies are merging in all kinds of flavors, in new, affordable products for consumer, office, industrial and medical markets, among others.
As the difference between “traditional” ICT equipment and AV devices was fading, it was decided a new “hazard-based” standard would cover both electronic equipment and IT/Communications technology. This led to the development of the IEC 62368-1, Audio/video, information and communication technology equipment – Part 1: Safety requirements.
IEC 62368-1 is intended to be more generic and technology independent, to simplify design and adoption to different markets, minimizing the need for national/regional differences.
The new standard should not be regarded as just an “update”, as it will introduce a new set of specifications that could even affect equipment that already complies with the existing IEC 60950-1 for ICT equipment and IEC 60065 for AV equipment.
As indicated, it adopts some fundamentally different engineering principles and terminologies, including the safety-centric approach. One should also have in mind that the 62368-1 applies not only to the end-user product, but also to components and subsystems such as power supplies.
From now on, product manufacturers therefore will have to consider this when procuring components and subsystems, to ensure these will be able to comply with the standard specifications.
The standard which has been published in its 3. edition, IEC 62368-1:2018, is applicable to the safety of electrical and electronic equipment within the field of audio, video, information and communication technology, and business and office machines with a rated voltage not exceeding 600 V (includes equipment rated 400/690V).
This does not include requirements for performance or functional characteristics of equipment. It is basically a product safety standard that classifies energy sources, prescribes safeguards against those energy sources, and provides guidance on the application of, and requirements for, those safeguards. The prescribed safeguards are intended to reduce the likelihood of pain, injury and, in the case of fire, property damage. This 3. edition cancels and replaces the second edition published in 2014.
The standard also apply to external power supply units and other accessories intended to supply other equipment within the scope of this part of IEC 62368.
This part of IEC 62368 does not apply to power supply systems which are not an integral part of the equipment, such as motor-generator sets, battery backup systems and distribution transformers.
In the US, it seems that continuing certification will be allowed for existing certifications that are not “significantly modified” after the Date of Withdrawal (DoW) in December 2020. In Europe though, the outgoing standards will be withdrawn in
favour of the new EN 62368-1 standard, and so presumptions of conformity with directives that reference the old standards will also cease. This is important to have in mind.
In Europe, the European Committee for Electrotechnical Standardization (CENELEC) is responsible for adjusting and harmonizing the IEC standards to regional requirements.
The resulting EU standard EN 62368-1 will formally be associated with the Low Voltage Directive (LVD), which relies on IEC technical standards to guide designers to produce safe products. The Low Voltage Directive version of 2014/35/EU, dated Feb. 26, 2014 was applicable from April 20, 2016. The technical requirements in this directive do not differ much from the older version. But it should be mentioned that the legal and general requirements have changed significantly (obligations of manufacturers, dealers, and marketers), and penalties are called for in the event of infringements of the directive.
The IEC Technical Committee TC108 has actually been working on IEC 62368-1 since 2002. As TC108 is also responsible for IEC 60950-1 and IEC 60065, they have implemented changes in the latest editions of both to ease the transition to the new standard. The first edition of IEC 62368-1 was adapted in the US in 2012. Europe followed in 2014 with the publication of the Second Edition. As such, the 62368-1, 60950-1 and 60065 standards have been co-existing for some time in North America and Europe, to help companies transition to the new standard without too much pain and expenses.
Companies that still have not taken the change of standards into consideration, should however do so asap, with only a few months to the DoW. Not only the design considerations and procurement of acceptable components, but also time-consuming testing and certification could impose some challenges to get products on the market in a timely manner.
Types of products covered by the standard is (as listed in Annex A):
Computing and networking products such as servers, PCs, routers, notebook/laptop computers, tablets and their power supplies
• Consumer electronics such as amplifiers, home theater systems, digital cameras and personal music players
• Displays and display units including monitors, TVs and digital projectors
• Telecommunication products such as network infrastructure equipment, cordless and cell phones, and similar communication devices, including battery-powered devices
• Office appliances like copiers and document shredders
• Various other types of audio/video, information and communication technology equipment used in homes, schools, data processing centers, and commercial and professional environments
Other equipment that has gained widespread use since the previous standards were introduced, like smartphones, tablet computers, wearable computers and so on would be included in the 3. Edition of IEC 62368-1.
The 3. Edition of IEC 62368-1 which was published in October 2018, comes with some technical changes over the previous edition, where the most important are:
• addition of requirements for outdoor equipment
• new requirements for optical radiation
• addition of requirements for insulating liquids
• addition of requirements for work cells
• addition of requirements for wireless power transmitters
• addition of requirements for fully insulated winding wire (FIW)
• alternative method for determination of top, bottom and side openings for fire enclosures
• alternative requirements for sound pressure
There is an interesting dispute going on with regards to a sub-clause in the European harmonized standard EN 62368-1, the paragraph “4.1.1.” that states “Components and subassemblies that comply with IEC 60950-1 or IEC 60065 are acceptable as part of equipment covered by this standard without further evaluation other than to give consideration to the appropriate use of the component or subassembly in the end-product.”
This paragraph is included in the current 2. Edition of the standard, but is to be deleted in edition 3. The paragraph is intended to help the transition, for instance by allowing use of complex components such as PSUs certified to legacy standards. But it’s controversial because it also could lead to unintended consequences, like inconsistent interpretations/applications and actually delay transition.
Potential problems could also occur as the legacy standards 60950-1 and 60065 classify energy sources and circuits differently. For example, a 60950-1 certified switched-mode power supply typically has output circuits classified as safety extra-low voltage (SELV), whereas IEC 62368-1 refers to ES1 energy sources, which considers both voltage and current. As a result, SELV is no longer defined.
However, TC108 has recognized that a SELV circuit is intended to be safe to touch by a user or operator, in the same way that an ES1 source is safe to touch by an ordinary person. To aid transition to the new standard, the two are regarded as offering equivalent levels of safety. Hence, interconnection of 60950-1 SELV circuits and 62368-1 ES1 circuits is considered acceptable in practice without exhaustive analysis.
Back to the hazard/safeguarding focus: IEC 62368-1 was written using hazard-based concepts, using a three-block model for pain and injury. It follows the HBSE (hazard-based safety engineering) methodology:
1. Identify energy sources in the product that are capable of causing pain or injury (i.e. electrical, mechanical, or thermal)
2. Classify those energy sources effect on the body or their potential for combustion (i.e. not painful/painful but not injurious/injury-causing, as well as ignition not likely/ possible/likely).
3. Identify safeguards that are needed to protect against the above: Some safeguard types include Equipment Safeguards, Instructional Safeguards and Installation Safeguards
4. Qualify those safeguards using performance or construction-based criteria.
TC108, among other IEC committees, has been committed to HBSE since the publication of the ECMA-287 Safety of Electronics standard, published in 2002, and maintains several hazard sub-teams focused on electric shock, fire, mechanical, chemical, radiation and other hazards for various product types and safety standards.
IEC 62368-1 references all energy sources applicable to ICT/AV electrical equipment, including electrical energy, thermal energy such as hot accessible parts, chemical energy encompassing electrolytic reactions or poisons, kinetic energy such as moving parts, and radiated energy including optical or acoustic energy.
Energy sources are classified into one of three levels according to magnitude and duration, as an expression of their potential to cause harm.
The three levels of effects from energy sources is described as:
Class 1: Not painful, but may be detectable. Ignition not likely.
Class 2: Painful, but not an injury. Ignition possible, but limited growth and spread of fire.
Class 3: Injury. Ignition likely, rapid growth and spread of fire.
The article quoted from Mascot.