STATUS SCIENTIFIC CONTROLS
FGD3 Infrared Gas Detector Heads
TD06/024
Issue:
7
Change Note:
1904
Page 7
3.4 Cable & Screening
The use of a screened cable is recommended for the installation of all detector heads.
The correct strategy for connecting the screens depends upon the area in which the
detector head is to be used (i.e. hazardous/non-hazardous). In all cases the screen
should not be connected at the detector head. Refer to the connection diagrams on the
following pages for further information.
The FGD3 infrared detector heads require a three-wire connection to the control unit:
Sig +
current loop to head
8.0-28V (25mA max)
0
0V return to control unit
Pwr +
supply for sensor
5.8-7.5V (60mA approx)
The infrared sensor requires a current of typically 60mA but draws this in pulses at a
frequency of 2Hz (approx).
Note:
Sig and + terminals must not be connected together. Although the detector head will
appear to function correctly, it will no longer be able to indicate detected gas levels to
the control unit.
3.4.1
Connection Instructions
With the head disconnected adjust the control unit output so that 5.8
– 7.5V can be
measured at the detector head between the wires ‘0‘ and ‘Pwr +’. Connect the head
and ensure that the voltage remains within the limits, readjust if necessary.
Summary of Contents for FGD 3 Series
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