Chapter 5 Installing the system

Page 5.1

5. Installing the system

5.1 What this chapter tells you

This chapter gives full instructions for installing the 7951.
It does not go into detail about how to install any peripheral devices (such as transducers, computers or printers) which
are connected to the 7951. For this information you must refer to the documentation supplied with these items.

5.2 Hazardous and non-hazardous environments

Caution:
Always refer to documentation supplied by the manufacturer for details of installing their equipment in
a hazardous area. The 7951 is neither intrinsically safe nor explosion-proof. and can therefore
only be used in a designated non-hazardous (safe) area.
If all or part of an installation is in an area where there is the risk of fire or explosion (which is almost always the
case when gases are involved), then safety barriers or galvanic isolators usually have to be wired into the
circuit. However, some instruments are explosion-proof and barriers are not, therefore, needed.

5.3 Installation procedure

Briefly, the procedure is:
Step 1: Draw up a wiring schedule.
Step 2: Unpack the 7951.
Step 3: Set the DIP switches.
Step 4: Fit the 7951.
Step 5: Make all external connections.
Step 6: Earth the installation.
Step 7: Connect power supply.
The steps in the procedure are explained in the following sections.

5.4 Step 1: Drawing up a wiring schedule

Before you make any connections, you must draw up a wiring schedule to help you identify wiring colours and
make sure that you do not connect more items of any given type than are allowed. (If you are in doubt, check
the specification in Appendix C.)
A blank copy of a wiring schedule is given in Appendix B.