Preview
Abstract
IEC 61984:2008 applies to connectors with rated voltages above 50 V and up to 1000 V a.c. and d.c. and rated currents up to 125 A per contact, for which either no detail specification exists or the detail specification calls up this standard for safety aspects. Changes with respect to the previous edition include: addition of new definitions, of new clauses, tables and annexes for clarification, improvement and better readability. The contents of the corrigendum of October 2011 have been included in this copy.

EN 61984:2009(Main)
Connectors – Safety requirements and tests
https://standards.iteh.ai/catalog/standards/clc/927ee01e-9437-4528-b933-3734c8707440/en-61984-2009

IEC 61984:2008 applies to connectors with rated voltages above 50 V and up to 1000 V a.c. and d.c. and rated currents up to 125 A per contact, for which either no detail specification exists or the detail specification calls up this standard for safety aspects. Changes with respect to the previous edition include: addition of new definitions, of new clauses, tables and annexes for clarification, improvement and better readability.

Applying the IEC 62368-1 standard to universal power adapters requires careful consideration of overcurrent and surge protection devices.

The regulation of power-based products and components is critical for design development and user safety. For decades, the International Electrotechnical Commission (IEC) has dictated how to design information technology equipment and audio/video products for safety. The IEC’s traditional approach to equipment safety has been product-dependent and incident-based, making the previous standards, IEC 60950-1(information and communication technology equipment) and IEC 60065 (audio and video equipment), more reactive and less adaptable to emerging technologies.

A new regulation, IEC 62368-1, became the single default standard on December 20, 2020. Thus, designers no longer can choose to comply with either the information/communication technology standard or the audio/video equipment standard. As the boundaries between information/communications and audio/video technology have blurred, the IEC 62368-1 hazards-based safety engineering standard applies to a broad scope of applications.

The new standard is less product-specific. It focuses on the energy within the equipment and the intended environments. This future-proof approach aims to encourage manufacturers to address known hazards in the design and intended use of the product, whether its application is for industrial or residential use.

Compliance testing

AC line protection components help increase product reliability and must comply with specific tests required by IEC 62368-1. It is necessary to decide on the overvoltage category that applies to determine the parameters of some of the tests.

Where the device connects to the electrical grid helps define the overvoltage category. The closer the proximity to the grid, the higher is the category and the hazard. For example, an electric meter on the outside of a house connected by a service wire to a transformer is considered Overvoltage Category IV. The electric breaker panel inside a home would be in a lower overvoltage category. Personal devices such as PCs, routers, notebooks, tablets, and related power supplies fall within Overvoltage Category II.

Using the Overvoltage Category along with the line voltage, engineers can determine the voltage withstand rating. Power adapters connecting to 120-V outlets have a withstand voltage rating of 1500 V. For adapters connecting to 240-V outlets, the withstand voltage rating increases to 2500 V. This rating is an essential basis for component selection and applicable tests.

The new standard also includes three tests related to varistors and gas discharge tubes (GDTs) for surge protection. The older standards did not have these tests. Varistors exposed to surge events can wear out over time, eventually becoming a hazard themselves. IEC 62368-1 now refers to a varistor as a possible ignition source, thus requiring additional tests.

Choosing a compliant solution for universal power adapters

Universal power adapters, commonly used in IT equipment, accept a wide range of voltage inputs, such as 90 to 240 VAC. This voltage range allows the product to be used worldwide with a common set of electronics. Safety requirements dictated by IEC 62368-1 require both overcurrent and surge protection.

Overcurrent protection

Selecting the correct fuse is critical to preventing damage from overcurrent events and passing fault testing. When choosing the right fuse, consider the following:

The fuse should both achieve its purpose within the circuit and remain intact when the circuit is operating normally.
The fuse must not nuisance trip. It must not open during either normal operations or surge pulse testing. To achieve this, calculate the predicted pulses’ energy and compare it to the fuse’s melting point. By targeting a proper ratio between the two values, engineers can be confident that the fuse will not nuisance trip during predictable pulses.
The voltage rating of the fuse must be at least as large as the maximum rating of the power supply or system voltage.
The fuse should have a maximum fault current rating higher than the maximum available fault current of the location where it will be used. This breaking capacity or interrupt rating determines how much current the fuse can safely interrupt.
The fuse should fit in available space.
The fuse must meet required third-party certifications, including UL or IEC requirements.

Use these requirements to identify the best fuse for the application. For example, Littelfuse recommends its 3.15-A fuse in the 215 Series due to a high breaking capacity of 1500 A at 250 VAC.

Surge protection

There are several surge protection technologies available. Safety components include varistors, TVS diodes, protection thyristors, and GDTs.

To determine the best solution for the application, engineers should first consider whether the ground is deemed to be reliable. Many home, office, and commercial spaces have unreliable ground connectors. Examples include wall sockets with a loose earth connector or a damaged ground terminal in the plug. Reliable ground connectors typically exist in industrial applications where the ground is hardwired or the equipment does not function without a good ground connection.

For unreliable ground applications, IEC 62368-1 states that when using varistors in the common mode, connections between High and protective earth or between Neutral and protective earth, consider using varistors with a GDT as long as they comply with the Annex G.8 varistor overload test. For varistors used in the differential mode, High-to-Neutral, the varistors must meet all the criteria described in Annex G.8.

To choose the right varistor, the minimum continuous operating voltage should be at least 1.25 times the maximum voltage rating of the equipment. Selecting the varistor’s required surge rating will determine the varistor’s diameter.

For the universal power adapter example, a 300-V thermally-protected varistor can protect the line-to-line and line-to-neutral connections from voltage transients and lightning while meeting minimum surge requirements. Consider using a 3000-V GDT combined in series with a 300-V varistor in both line-to-ground and neutral-to-ground connections.

While this is the most common surge protection solution for many electronic applications, designers can also consider other solutions. When comparing technologies, engineers should consider the component’s:

Clamping voltage, which shows how well the device can protect during a surge event, with lower being better
Let-through energy during a surge event, again, lower is better
Leakage current
Lifetime after multiple surge events
Size and cost.

IEC 62369-1 provides flexibility for safety requirements

IEC 62369-1 introduces a new way to approach electronics product testing by requiring engineers to consider known hazards and use environments when designing a product. This hazards-based approach aims to keep pace with technological advances while giving product designers more flexibility within the framework.

Minimum transient voltage withstand rating
is determined by the AC mains voltage

PCs, routers, notebooks, tablets, and their power supplies
fall within Overvoltage Category II

Table 12 in section 5.4 specifies the following: 120 VAC
power supplies will need to withstand 1500 Vpk; 240 VAC
power supplies need to withstand 2500 Vpk

In this Power 101 video we dive into IEC 60335-1, the safety standard for household appliances. With the evolution of IoT and smart devices, household appliances now have wireless connectivity, graphical displays, and other features commonly associated with ITE applications. Learn more as we compare key differences between IEC 60335-1 and the ubiquitous IEC 60950-1.

A Shift to Hazard Based Safety Engineering
https://www.cui.com/iec-62368-1-power-supplies

IEC 62368-1 is an international safety standard that applies to electronic equipment designed for information and communication technology (ICT) and audio-visual (AV) applications. It combines and replaces the long-standing IEC 60950 (ITE applications) and IEC 60065 (AV applications) standards. The standard approaches product safety differently than those it replaced by applying the principles of Hazard Based Safety Engineering (HBSE), which uses a three-block model to identify hazards and determine appropriate safeguards.