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9.11 Releasing the thermical
safety devices
9.11.1 Variety of thermal protection
devices in use
For overheat protection, the steam humidifier
is equipped with one or two thermo switches,
depending on the power output rating. They
are mounted on the steam cylinder cover.
The thermo switch/es is/are coupled to the
heater element/s by means of a capillary
tube. Each of thermo switch controls 1 to 3
heater elements. Thus, with 6 heater element
units, each one of the thermo switches is
assigned to a group of 3 heater elements.
For additional safety in case of one of the
thermo switches beeing defective, a Klixon
thermo switch is screwed to the cylinder
cover.
The mounting positions of a single thermo
switch and the Klixon are shown in the next
section in an exemplary representation.
Supplementary to the thermal protection
devices in conjunction with the steam cylin-
der, the solid state relay/s is/are protected by
bimetal switches to avoid damage introduced
by inadequate ventilation due to e.g. vent
holes that are obstructed.
From an electrical point of view, the thermo
switch/es on the cylinder cover, the bimetal
switch/es on the soid state relay/s as well as
the Klixon thermo switch mounted on the cyl-
inder cover are all wired in series. If one of
the devices mentioned triggers due to an
overheat situaton, the main contactor K1
switches off and controls enters the „120“
error state (i.e. „Thermo switch“). Steam pro-
duction is then interrupted. A unit restart is
required which is, however, only possible
after the bimetal switch/es has/have cooled
down and/or the thermo switch/es and/or the
Klixon thermo switch (see sections 9.10.2
and 9.10.3) were unlocked.
In case that a thermal protection device trig-
gers repeatedly, check for possible cause
prior to any further use of the unit.
9.11.2 Unlocking of a thermo switch
on the cylinder cover
Whether a thermo switch and, if so, which of
the devices, has triggered, may be detected
by a passage measurement (let the unit cool
down before starting the measurement!).
Unlocking is then accomplished as such:
Slightly push down the red button (see fig. in
section 9.11) protruding a few milimeters
from its holder. This will make the button
return to its original position and unlock the
mechanism.
Relasing a thermo switch does not erase the
fault message in the control fault memory.
9.11.3 Unlocking of the Klixon
thermo switch
Whether the Klixon thermo switch has trig-
gered, may be detected by a passage mea-
surement (usually, when overheat is
encountered, the thermo switch/es trigger).
Unlocking is accomplished by pressing the
unlocking pin located between the electrical
connection contacts of the Klixon switch (see
fig. in section 9.11).
Please note
