Electrical Connections; Field Terminal Access - GasTech D-Guard2S Operator's Manual

9.6.

Electrical Connections

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D-Guard requires only two connections to be made in order for it to function. These two connections convey
input power and return the process related current signal.
The functions of both power supply and signalling are therefore carried out over the same pair of wires.
2
For D-Guard variants with HART communications, the digital signal also uses the same two wire connections.
9.6.1

Field Terminal Access

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Access to the D-Guard field terminals involves opening the enclosure, which is achieved by undoing the four
corner lid screws using a 4mm Allen Key.
The main electronics are fixed to the front panel (Lid) of the enclosure and the input power and loop-return
connection is located to the bottom right of the circuit board as viewed from the rear of the board (shown in
the diagram below).
Removing the lid of the enclosure, exposes a number of critical system elements that must be treated
with care in order to maintain the operational integrity of the instrument.
Avoid touching the circuit board with hands or tools.

Avoid disturbing the sealing gasket that sits in the groove along the edge of the base section

of the enclosure. This seal is essential for correct ingress protection.
Depending on the build of the instrument, connection to the main system board can be either direct to the
power connector or via a terminal board mounted in the base section of the enclosure. Connection directly to
the system board connector, is suitable for lighter duty cables (single or dual screened, twisted pair type cables).
See section 8.6.5 for cable types.
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2
D-Guard
Power Connector