Understanding IEC 60079-11:2023: Major Changes in Rating and Electrical Components
Welcome back! If you have already read our previous blog post about the Enclosures, Connections and Encapsulation new IEC 60079-11:2023, you can proceed to the next chapter to describe rating and electrical components changes.
For our new readers, let me introduce the topic briefly. In early 2023, IEC 60079-11 Edition 7 was published, featuring over 100 changes. This blog series aims to explain some of the major changes to provide you with a guide for understanding the most important aspects of these updates. In addition to this post, to gain a comprehensive understanding of the standard, please check out our previous article on enclosures, connections, and encapsulation requirements changes.
Now, let’s get started!
Rating of Components on Which Intrinsic Safety Depends in IEC 60079-11:2023
According to the 7th Edition, it has been stated that equipment possessing a Level of Protection designated as ‘ia’ or ‘ib’ must not exceed 2/3 of its maximum current, voltage, and power rating.
For components that the intrinsic safety depends on at Level of Protection ‘ic’, a safety factor of 1.5 is not mandatory if the circuit remains within the defined maximum current and voltage rating,
Does not surpass the defined maximum power rating during non-countable faults.
During normal operation, the equipment should not surpass 2/3 of its power rating.
Components for Level of Protection ‘ic’ are considered to fail if they are not within their manufacturer’s rating following the application of faults. [Clause 7.1]
Components Which Have a Conductivity Between Conductors and Insulators – Semiconductors
‘Analysis of integrated circuits based on failure rates of particular failure modes other than stated is not permitted by this document.’ – IEC 60079-11:2023
Namely: This clarifies that the assessment of semiconductors cannot be considered based on failure rates. [Clause 7.7.1]
Another new requirement in this Edition 7 is the usage and explanation of those programmable components. For all Level of Protection at service temperature definition shall be assumed that this component operates normally. [Clause 7.7.8]
Element That Reacts to a Small Change in an Electrical Current - Relays
The latest edition of the standard, IEC 60079-11:2023, now provides detailed explanations regarding the rating criteria for relays, which encompass requirements related to dielectric strength and connection to an intrinsically safe circuit.
One noteworthy change introduced in IEC 60079-11:2023 is that it considers the gap between a relay’s coil and contacts as a fault for relays that rely on intrinsic safety. On the other hand, relays for ‘ic’ circuits are only required to comply with the relevant industrial standards.
Additionally, if the current or power value exceeds the specified threshold for relays with reduced separation, an additional acceptance criterion has been included to the standard, as outlined in [Clause 7.9.2], which references IEC 61810-1: Electromechanical elementary relays – Part 1: General and Safety Requirements.
IEC 60079-11:2023 Device That Provides Overcurrent Protection – Fuses
In the world of electrical safety, even a tiny component like a fuse plays a crucial role, and IEC 60079-11 Edition 7 brings some noteworthy clarifications to fuse usage.
‘A single suitably rated fuse is sufficient to provide protection.’ – IEC 60079-11:2023
Another new part of the chapter is that the cold resistance of a fuse cannot be used to limit the breaking current. However, this does not exclude the use of the cold resistance to limit current in the rest of the circuit or to protect other components.
This point also explains that fuses connected to the main supply are permitted to have a breaking capacity of less than 1500 A. In this case, the manufacturer shall specify the maximum prospective current allowed for the circuit in their instructions. [Clause 7.11]
Energy Storage Devices Using Reversible Adsorption and Desorption – Supercapacitors
As per the established Edition 7 standard, supercapacitors are categorized as cells and batteries. [Clause 7.12.1]
In Intrinsically Safe equipment, it is permissible to connect supercapacitors in parallel without compromising intrinsic safety. However, it is important to note that supercapacitors have
the capability of storing energy based on their specified capacitance,
but they do not have the ability to regulate their voltage. [Clause 7.15]
Temperature-Sensitive and Monitoring Components- Thermal Devices Changes in IEC 60079-11:2023
The latest version of IEC 60079-11 has introduced a dedicated chapter for Thermal Devices, accompanied by additional requirements and evaluative procedures. [Clause 7.16]
Temperature sensors may be utilized for the purpose of ensuring intrinsic safety; however, it is inevitable that they comply with Table 19 – Rating and failure modes of temperature sensors. [Clause 7.16.2.2]
Positive Temperature Coefficient (PTC) and Polymer Positive Temperature Coefficient (PPTC) devices are now allowed to limit temperature without requiring extra control circuits. Aligned with they are compliant with the relevant requirements and Table 21 – Rating and failure modes of PTC devices used to limit temperature. [Clause 7.16.2.4]
When It All Seems Too Much…
In this and in the previous post we have provided an overview of 11 major changes introduced in IEC 60079-11 Edition 7. In the final part of this blog series, we will summarize 5 other significant modifications, ensuring you’re well-informed about the latest updates.
If you are keen to explore more on this topic, we have a wealth of additional content available on our website. Discover ‘How to Prevent Hazards in HAZARDOUS Locations?’ or delve into the intricacies IECEx and ATEX Certification.
Do you have any questions or need further clarification on this subject? Do not hesitate to schedule a meeting directly with our CTO via our website or reach out to our engineers via email. We’re committed to assisting you efficiently in obtaining your certificate in accordance with the IEC 60079-11:2023 standard.
