For either Level of Protection “ia” or “ib”, what are the current limiting devices that are required to be disabled (or equivalent e.g. not fitted, short-circuited or removed) by IEC 60079-11:2011, Subclause 10.5.3 b), and what are the current limiting devices that need not be disabled?
All discrete protective devices that can be schematically represented as individual devices apart from the cell are to be disabled for the purposes of testing according to IEC 60079- 11:2011, Subclause 10.5.3 b), regardless if they are located inside the cell or if they are external to the cell. This includes, but is not limited to resistors, fuses, resettable fuses (NTC, PTC, PPTC), CID (current interruption device), semiconductors, etc.
Features that provide essential cell functions, such as a separator with shutdown function or the ohmic resistance of the electrolyte, are not considered current limiting devices in the sense of this clause and need not be shorted or removed, and such cells can be considered for Level of Protection “ia”.
Source: IEC 60079-11 Edition 6.0 2011-06 EXPLOSIVE ATMOSPHERES – Part 11: Equipment protection by intrinsic safety “i” INTERPRETATION SHEET 6
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