thuba PTB 24 ATEX 1002 X Manuel page 7

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3.1.1 Self-limiting heating cable
The stabilized operating mode is achieved by
the use of self-limiting heating cables. The
design is based on the characteristic and the
system parameters. Only connection parts and
cable end fittings that have been certified togeth-
er with the heating cable in an EU Type Exami-
nation Certificate for the complete system may
be used. In addition to the EU Type Examination
Certificate, an instruction manual and planning
documents, the marking of the complete system
is included in the scope of delivery.
3.1.2 Stabilized design with low heat output
In addition to self-limiting trace heating systems,
the heat output of a trace heating system can be
limited in such a way that, due to the low heat
output, the given maximum surface temperature
of the temperature class cannot be exceed
under any circumstances.
3.2 Controlled operating mode
Applications that use a temperature control
device and a safety temperature limiter to limit
the maximum permissible surface temperature.
The safety temperature limiter must operate
independent of the temperature control device.
The safety temperature limiter shall be integrat-
ed into the installation in such a way that
exceeding the maximum permissible surface
temperature can be reliably prevented. If a safe-
ty temperature limiter trips or in the event of a
fault (sensor break), the trace heating system
must stay de-energized until the malfunction has
been remedied or the faulty device replaced.
The setting of the rated tripping temperature of
the safety temperature limiter must be carried
out in a protected manner, either in an explo-
sionproof connection box or in the electrical con-
trol room.