Product
description
RG 210
7
Probe
The control unit and the PTC thermistor probe are connected by
means of a signal cable. The tip of the probe is equipped with a PTC
thermistor. During operation, the PTC thermistor is heated and can
distinguish between gaseous and liquid media due to the different
heat dissipation.
1
Plastic screw
connector
2
Probe cable
3
Brass weight
4
Protective sleeve
for PTC thermis-
tor
Fig. 2: Probe type 150
Fig. 3: Probe type 937
3.1 Operating
modes
When the mains voltage is switched on, the connected PTC thermis-
tor heats up. Three different operating modes must be distinguished.
The various operating modes are set by means of a selector on the
printed circuit board.
Operating mode “Probe 1”: level switch
Only the signal received from probe 1 is processed. A second probe
may be connected, but it will not be considered.
If the PTC thermistor is exposed to air (i. e. not submerged in liquid)
once probe 1 is fully heated up, the yellow LED "Probe 1" goes out,
the green LED "Release" lights up and the output relay is energised.
If the PTC thermistor of probe 1 is submerged in liquid or if the heat-
up process of probe 1 is not yet finished or if probe 1 is not con-
nected or short-circuited, the yellow LED "Probe 1" lights up, the
green LED "Release" goes out and the output relay is de-energised.
Operating mode "Filling": level control for filling
Both PTC thermistor probes "Probe 1" and "Probe 2" must be con-
nected. The following applies to both probes in this operating mode:
If the PTC thermistor is exposed to air (not submerged in a liquid)
