S+S REGELTECHNIK THERMASREG FST Bedienungs- Und Montageanleitung Seite 7

G
Mounting and Installation
FUNCTION:
Contact: ................. C - 2 danger of frost ⁄ sensor breakage
C - 3 normal operation
The switch inside frost protection thermostat FST responds (closes
contact C - 2) when temperature falls below the preset temperature
setpoint over a capillary tube length of at least 40 cm. Simul taneously
contact C - 3 breaks and can be used as a signal contact. Resetting
(closing contact C - 3) happens automatically when temperature rises
above the preset setpoint value again (on type FST - xR resetting must
be done manually by pressing the reset button).
FST is "intrinsically safe", i. e. in case of damaging the capillary tube-
membrane system, it switches automatically to cooling function.
Contact C - 2 closes and therefore can be used as operating contact.
The air temperature is detected over the entire sensor length (capil-
lary tube). The gas - filled (R 507) membrane system and the capillary
tube constitute one measuring unit, which is mechanically coupled to
the microswitch.
Capillary tube: The capillary tube is laid uniformly at the hot side of
the air heater to be protected (in case of air coolers in front of the
air cooler) at a distance of ca. 5 cm crosswise to the heat exchanger
tubes over the entire area. For test purposes it is recommended to
make a loop of ca. 20 cm directly underneath the enclosure and before
entering the air duct. To avoid damaging the capillary tube, a minimum
bending radius of 20 mm must be observed. Installation is facilitated
by using the mounting clamps available under accessories.
Frost simulation: The frost situation can be simulated and functioning
of the device can be tested by dipping the capillary tube testing loop
into a pot filled with ice water.
Notes regarding FST
A preset setpoint value can be lead-sealed at the adjusting screw. It is absolutely necessary to ensure that ambient temperature at the
device does not drop below the preset setpoint temperature. This device must be operated in a non-precipitating pollutant-free ambience.
Scheme
Normal
1
operation
Danger
0
of frost
cold
w
Mounting diagram
SD
T
warm
FST
C
2
3
C
2
3
FST