IEC 60079-11:2023/ISH5:2025

INTERNATIONAL ELECTROTECHNICAL COMMISSION
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IEC 60079-11
Edition 7.0  2023-01
Explosive atmospheres -
Part 11: Equipment protection by intrinsic safety “i”

INTERPRETATION SHEET 5
This interpretation sheet has been prepared by subcommittee 31G: Intrinsically-safe apparatus,
of IEC technical committee 31: Explosive atmospheres.
The text of this interpretation sheet is based on the following documents:
DISH Report on voting
31G/424/DISH 31G/431/RVDISH
Full information on the voting for the approval of this interpretation sheet can be found in the
report on voting indicated in the above table.

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IEC 60079-11:2023 (Edition 7.0)
EXPLOSIVE ATMOSPHERES – Part 11: Equipment protection by intrinsic safety “i”
Background
Figure D.1 of Annex D shows a possible circuit configuration that defines measuring points for
current (8) and voltage (12) at the output of an intrinsically safe source. Clause D.2 describes
U as the voltage value used for the steady state assessment limited at (5). Clause D.8
LIM
defines that the energy is determined during the time when U or I is exceeded.
LIM LIM
Depending on the load (9) or (11), the voltage level U could be exceeded at (5) even when
LIM
the voltage at (12) is below the level of U . In this case, there might be transient energy even
LIM
when the voltage at (12) is below U .
LIM
Question 1
When does the determination of transient
...