FEATURE TEST & COMPLIANCE
Setting the Standard EN62368-1 and hazard-based safety engineering
With new safety standards set in place to ensure faultless eletronic performance, FiDUS Power outlines the relevant safeguards and information, to clarify exactly what’s involved when it comes to classifying an electronic hazard
I
EC TC108 is the technical committee that advises CENELEC on the topic of standardisation of safety for audio/ video, information and communication technology equipment. Together, they have produced a new standard which incorporates these with initial input from ECMA TC12. The call for the new standard has mostly been driven by devices like mobile phones, which are a combination of all three: a compact computer, audio/visual support and vitally, a communication device. The standard covers equipment such
as: PCs, mobile devices and power supplies. For the standard to encompass all of these different products, it must be technologically independent and more hazard based; or, in other words, based on good engineering principles, as opposed to product specifics. This results in a more performance based approach: the products are qualified on test results, as opposed to construction regulations. Each hazard clause is laid out stating;
the objective of the clause, the energy source, the supplemental and reinforced safety measures, location of the safeguard and finally, the tests to verify hazard mitigation. Injury only occurs when the hazard (predominantly electrical sources of energy, but can be others; heat, fuel, mechanical, radiation etc.) has a transfer
mechanism that permits the transfer of significant energy, for a noticeable time, to the body. To clarify the types of energy source covered, they are split into three classes.
DEFINING THE CLASSES
A class one energy source has levels not exceeding class one limits under: normal operating conditions, abnormal operating conditions that do not lead to a single fault condition and single fault conditions that do not result in class two limits being exceeded. Under normal operating conditions and abnormal operating conditions, the energy in a class one source, in contact with a body part, may be detectable, but is not painful nor is it likely to cause an injury.
A class two energy source has levels exceeding class one limits, but not exceeding class two limits under the same conditions. The energy in a class two source, under contact with a body part, may be painful, but won’t cause injury. For fire, however, the energy in a class two source can cause ignition under some conditions. A class three energy source has levels exceeding class two limits under the same conditions, or any energy source declared to fall under class three. The energy in a class three source can cause injury. For fire, the energy in a class three
source may even cause ignition, and the spread of flame where fuel is available.
THE SAFEGUARDS OF THE NEW STANDARD
Safeguards against these are classified in three levels under the new standard: Basic safeguards – effective under both normal and abnormal working conditions. Supplementary safeguards – effective in the event of a single fault of any part, including the basic safety guards. Reinforced safeguards -effective under normal and abnormal operating conditions and single fault condition. Each of these are graded as follows: Equipment safeguards -inherent in the product and not reliant on the user to implement or influence the effectiveness of those safeguards. Installation safeguards -the installer
must be competent in installation, as a safeguarding characteristic is achieved with correct installation. Behavioral safeguards -when the energy source is accessible to the user. The planned change to the new
standard will arrive on December 20, 2020. To ease the transition to the new standard, an additional clause - 4.1.1. - has been added to the current revision of the standard: “Application requirements and acceptance of materials, components and subassemblies”. This essentially permits the continued use of IEC60950-1 components as part of the system. The current revision states that this will be removed in the next revision. However, the IEC TC108 interpretation panel plans to keep the clause in for longer, and it will not be removed with the latest update of the standard. Nonetheless, FiDUS POWER have already begun the transition to the new standard. All current ITE products will be updated: none will be facing obsolescence as a result of the migration.
FiDUS Power
www.fiduspower.com 20 SEPTEMBER 2019 | ELECTRONICS / ELECTRONICS
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