Liebherr WKt 4552 GrandCru - Manual (Page 20)

20
Alarm condition
Normal operation
Open or close A1– 6 to GND
Alarm inputs A1– 6
Any contractors
normally open or closed
GND GND
GND
GND
A1 A2 A3 A4 A5 A6
COM
COM
N.O.
N.C.
LK(U)v, LCv, LK(U)exv, LG(U)ex and LGT laboratory appliances with Comfort-Controller
+
-
+
-
Normal operation Alarm condition
e.g. green lamp
indicating normal
opretaion
external power supply
e.g. red lamp
indicating alarm
condition
external power supply
N.O.
COM
N.C.
N.O.
COM
N.C.
Example: GSM dialer alarm system using volt free alarm contact
External alarm contact connection
Volt-free contact
All LK(U)v, LCv, LK(U)exv, LG(U)ex and LGT models have an integrated volt-free contact. The relay contact can be wired into a warning system in the building which
would advise e.g. security personnel or a janitor outside of working hours. Warning systems with audio or visual alarms are possible.
The following example shows a circuit with a visual alarm. Either normal operation or alarm condition or both can be indicated. Either AC or DC circuits are possible,
max AC 230 V / 5 Amp.
Example: visual alarm system using volt free alarm contact
Alternatively, if no internal warning system is in place and additional wiring inside the building is problematical, the volt-free contact can be used in conjunction
with e.g. a GSM alarm dialler. There are many different versions of GSM alarm dialers available on the market which either call a telephone number and/or send a
text message in case of an alarm. Depending on the specification of GSM alarm dialers, potentially many appliances can be connected to one dialler. Being GSM
appliances, only a SIM card and a power supply are required.
The following example shows a circuit with a GSM dialler: A change in relay setting activates the alarm function of the dialler and thus initiates either a telephone
call or an SMS to pre-defined numbers with a pre-recorded message. The dialler in the example has 6 addressed alarm inputs. This could be 6 individual appli-
ances or 6 rooms, each with several appliances wired in series.
In spite of all efforts to produce appliances of unequalled reliability, Liebherr strongly recommends that the volt-free contact is wired into some kind
of independent and external warning system. Please take a few moments to consider the value of the contents of the refrigerators and freezers under
your supervision. The cost of such a warning system is often negligible in comparison to the value of the contents.