JUMO 14597 safetyM STB/STW Ex - Safety Temperature Limiter and Safety Temperature Monitor Operating Manual - Manual (Page 79)

7 ATEX
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- If the JUMO safety
M STB/STW Ex is used in the single-channel device variant to monitor non-electrical ignition sources
and a warning is issued on demand, the user must take immediate measures to achieve a safe status.
7.4 Associated intrinsically safe electrical apparatus according to EN 60079-11
7.4.1 Function of intrinsic safety
The intrinsically safe ignition protection "i" makes use of the fact that a certain amount of energy is required to ignite a poten-
tially explosive atmosphere. This depends on the composition of the potentially explosive atmosphere.
If it is made impossible for this energy level to be exceeded in an electrical circuit, meaning that neither sparks from switching
nor thermal effects can cause ignition under certain test conditions and when certain safety margins are observed, the electri-
cal circuit is intrinsically safe.
7.4.1.1 Definitions for intrinsic safety
An intrinsically safe electrical circuit is an electrical circuit in which neither a spark nor a thermal effect occurring under the con-
ditions specified in EN 60079-11 – which include uninterrupted operation and certain fault conditions – can cause ignition of a
specific potentially explosive atmosphere.
The energy in the electrical circuit is therefore limited so that it never reaches a sufficient level to cause ignition. This applies to
sparking and to thermal effects. The test conditions with specific potentially explosive atmospheres are specified. The tests
cover uninterrupted operation and specified fault conditions.
7.4.1.2 Electrical apparatus:
Electrical apparatus is the collective term for electrical components and electrical circuits or parts of electrical circuits that are
generally found in a single case.
7.4.1.3 Intrinsically safe electrical apparatus:
Electrical apparatus in which all electric circuits are intrinsically safe.
7.4.1.4 Associated electrical apparatus
Electrical apparatus in which not all electrical circuits are intrinsically safe. In terms of construction, the non-intrinsically safe