Understanding IEC 60079-11:2023: Major Changes in Cells, Batteries and Tests
Ready for another dive into the IEC 60079-11:2023 standard? It’s been a year since the introduction of the “new” IECEx intrinsic safety “i” standard! 🎉. In this final blog post of our series about Edition 7, we’ll focus on cells and batteries with the related chapters.
But before we begin, consider checking our previous articles on IEC 60079-11:2023. In the previous two blogs, we explored the changes in Enclosures, Connections, and Encapsulation alongside the Ratings and Electrical Components chapters.
Let’s take the first step towards concluding our journey in IEC 60079-11:2023!
Protection Against Polarity Reversal
Firstly, what is polarity reversal? This is when the positive and the negative polarity on the battery is reversed. During installation, ensure the correct polarity connection to prevent damage or sparks. Every intrinsically safe apparatus must prevent polarity reversal, like:
- power supplies to intrinsically safe apparatus, or
- at connections between cells of battery or supercapacitors.
For this purpose, a single diode (with intrinsic safe rating) is acceptable. [Clause 6.8]
Another way of protection can be a mechanical poka-yoke design that makes the wrong polarisation physically impossible.
Cells and Batteries Design Requirements in IEC 60079-11:2023
The most requirement change and clarification get involved in the cells and batteries clauses in IEC 60079-11:2023. So, firstly let’s check the points that relate to the design aspects of cells and batteries.
Primary and Secondary Cells and Batteries - General
Some cells and batteries, like lithium-ion, may catch fire during a short circuit at a reversed connection. The previous Edition 6 standard allowed the use of lithium-ion cells. Of course, if those were tested following the standard. Next to that, required a declaration from the manufacturer to confirm the safe use of them in intrinsic safe apparatus. Edition 7 deleted this section. Lithium-ion or other cells and batteries are now usable if they successfully pass the specified tests, eliminating the need for an additional declaration.
The following requirement refers to an intrinsic safe (IS) apparatus in which one’s batteries permitted to charge inside an explosive atmosphere is present. At temperature rise needs to be considered electrolyte leakage therefore at testing of charge electrolyte leakage must be observed. [Clause 7.12.1]
Battery Structure Connected with IEC 60079-11:2023
When a battery structure is designed with internal separation based on Edition 7, short circuits between cells do not need to be considered. However, a single-cell short circuit shall be considered a non-countable fault. The exception to this is the surface temperature test when a single cell is considered to fail to short circuit. [Clause 7.12.2]
Ventilation at Cells and Batteries
For IS apparatus containing chargeable batteries inside hazardous areas, the manufacturer must demonstrate that the concentration of hydrogen level does not exceed the defined values.
The manufacturer does not mean the manufacturer of the battery – clarified by IEC 60079-11:2023 Edition 7.
This chapter declares a test criterion, too. The cell containers, which ones sealed (that enclose the cells) do not need to submit to pressure test in accordance cells and batteries test requirement chapter (9.14.4) in IEC 60079-11:2023. [Clause 7.12.4]
Cell Voltages Test Requirements
In IEC 60079-0 Explosive atmospheres – Part 0 Standard contains a table about cell (primary and secondary) voltage. When your choice of the cell cannot be found in this table, it shall be tested to find the nominal voltage of the cell. This test was detailed in Edition 7:
- Testing process: referring to the test chapter (9.8) in the current Standard
- Test temperature: maximum open circuit voltage at room temperature
- Charging after the test: needs to use the manufacturer-specified method
Test of Cells and Batteries in IEC 60079-11:2023
In connection with the above chapters, let’s dive into cell and battery testing requirements.
Cells and Batteries – General Conditions of Testing
Preparation of test:
- Edition 7 clarified that a cell or battery for testing purposes always needs to be new and previously unused.
- For tests the removal of the current limiting device is required.
- For dust layer tests every testing temperature and required sample quantity has been defined in IEC 60079-11:2023.
During the testing process:
Every test requires continuous current and voltage under cell and battery tests. Any sudden drop in current or voltage was not allowed. To be insured the testing conditions are stable.
Result of the test:
When the test result is an explosion or fire of the cell (or battery), those are prohibited to use for Level of Protection “ia” or “ib”.
Electrolyte Leakage Test Requirements of Cells and Batteries
This section of the IEC 60079-11:2023 describes test parameters, and what the samples need to undergo. There is a new criterion for Level of protection “ic”: testing is not required but is sufficient to establish compliance with electrolyte leakage requirements.
There is also an alternative testing assessment for sealed case batteries. After the described test the sample can be placed for 12 hrs on blotting paper and evaluated after that.
Spark and Thermal Ignition Tests of Cells and Batteries
For cells not changed in explosive atmospheres, a single cell is not required to be tested for spark ignition in case the peak open circuit voltage is less than 4.5V. [Clause 188.8.131.52]
From the thermal ignition point of view, the IEC 60079-11 Edition 7 declared that temperature measurement shall be done (at a single-cell test) in the middle of the cell concerning its longitudinal axis.
Level of protection “ib” gets an alternative test for lithium-ion rechargeable cells. Next to that, at Level of Protection “ia” and “ib” always need to use requirements of 7.12.3, if electrolyte leakage appears during the maximum surface temperature test. A new statement was added in IEC 60079-11:2023 referring to thermal ignition. Only a single sample needs to be tested for compliance with the Level of Protection “ic” thermal ignition. [Clause 184.108.40.206]
Routine Verifications and Tests in IEC 60079-11:2023
In IEC 60079-11 Edition 7 the routine test became more specified and detailed. For batch verification of conformal coating and encapsulation, the standard contains exact numbers based on ISO 2859-1 [Clause 10.4].
For transformers with Level of Protection “ic”, the following new rule was added. If the relevant industrial standard does not require a routine test, no routine test is required according to Edition 7. [Clause 10.3.2].
I Think This Is a Good Place to Stop
Starting a new product design or improving your current product for explosive atmospheres is not an easy task. I hope I was able to support your work with this blog series. It is not a sorrowful ending so let’s keep it short. Thank you for sticking with me through the IEC 60079-11:2023 world.
Happy New Year and good luck with your intrinsic safe project!
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