Afriso EURO-INDEX OWWG3 Series, Operating Instructions Manual

Page: 49 / 156

Product description
ÖWWG 3 9
Control unit
The control unit contains the following elements in an impact-
resistant plastic housing: display elements and controls as well as all
electronic components for signal processing and conversion of the
probe signal into a digital output signal. The output signal is available
as a voltage-free relay contact (changeover contact).
a Green LED
B Test button
c Red LED
d Acknowledge
button
e Without function
f Reset key
Fig. 2: Control unit
3.3 Function
When the mains voltage is switched on (green LED is on), the PTC
thermistor heats up. Until the operating temperature is reached, the
audible alarm sounds and the red LED is on. After approx.
8 seconds, the PTC thermistor has reached the operating
temperature (unless it is submerged in liquid) and the control unit is
automatically unlocked, i.e. the audible and visual alarms are
deactivated and the relay is energised.
When the heated PTC thermistor is submerged in liquid, it cools
down and changes its resistance. This change in resistance causes
the control unit to trigger visual and audible alarms. At the same
time, the relay is de-energised. The audible alarm can be muted with
the "Acknowledge" button in the case of an alarm. The visual alarm
remains on as long as the alarm condition persists. When no alarm
condition is present, the relay is energised. If the PTC thermistor is
submerged in liquid or in case of a short circuit or a line interruption,
the relay is de-energised. ÖWWG 3 is locked in case of an alarm, i.e.
the alarm remains on after the problem has been fixed until
ÖWWG 3 is unlocked by means of the Unlock pushbutton. In order
to prevent misuse of this pushbutton, the control unit signals an
alarm when this pushbutton is pressed.