C 150 (E2) 06/2011
page 44/78
10.3 Zero-voltage relay alarm output
Collective alarm output via the zero-voltage relay alarm contact
The CO
2
incubator is equipped at the rear with a zero-voltage relay output (13) for the temperature and
CO
2
, which permits the transmission of alarms to an external monitoring system in order to monitor and
record the alarm signals.
The zero-voltage relay alarm output switches immediately, as soon as the red LED “ALARM” lights up on
the controller display. The zero-voltage relay alarm output switches for alarm instances listed in chap.
10.1 and in case of power failure.
If the external alarm monitor is connected via the contacts C and NO, alarm monitor-
ing will take place with protection against short-circuiting, i.e., if the connection be-
tween the C 150 and the external alarm monitor is interrupted, an alarm is triggered.
In this case, power failure will also trigger the alarm.
Figure 25: Zero-voltage contacts circuit diagram
C
NO
NC
ALARM
In case there is no alarm, contact C closes with contact NO.
Closing contact C with contact NC switches the zero-voltage relay alarm output.
Maximum loading capacity of the switching contacts: 24V AC/DC – 2.0 Amp.
DANGER
Electrical hazard.
Danger of death.
Damage to switching contacts and connection socket.
∅
Do NOT exceed the maximum switching load of 24V AC/DC – 2.0 Amp.
∅
Do NOT connect any devices with a higher loading capacity.
The alarm message on the controller display remains displayed during transmission of an alarm via the
zero-voltage relay outputs.
As soon as the cause of the alarm is identified and resolved, the alarm transmission via the zero-voltage
relay outputs resets automatically together with the alarm message on the controller display.
In case of a power failure, transmission of the alarm via zero-voltage relay outputs remains active for the
duration of the power failure. Afterwards, contact C will close automatically with contact NO.
Connection to an external monitoring system
To ensure short-circuit-proof alarm monitoring that will trigger the alarm when the C 150 is connected to
an external alarm monitor, connect the external alarm monitoring system to the C 150 via the C and NO
contacts.
Figure 26: Connection to an external monitoring system
•
Insert a suitable slotted screwdriver into the
opening in the terminal strip above contact
C.
•
Press the screwdriver carefully into the
opening. The contact C terminal will open.
•
Insert the bare end of one of the two cables
on the external alarm monitoring system
into the terminal opening and remove the
screwdriver from the terminal strip.
•
Follow the same procedure with the other
cable on the external alarm monitor, which
you can either connect to contact NC or
NO.
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