Page 144 ST 700 SmartLine Pressure Transmitters User’s Manual Revision 13
Figure 55 – ST 700 Basic Transmitter - 3-Screw Terminal Board and
Grounding Screw
As shown in Figure 55 each transmitter has an internal terminal to connect it to earth ground.
Optionally, a ground terminal can be added to the outside of the electronics housing. While it is not
necessary to ground the transmitter for proper operation, doing so tends to minimize the possible
effects of noise on the output signal and affords protection against lightning and static discharge. An
optional lightning terminal block can be installed in place of the non-lightning terminal block for
transmitters that will be installed in an area that is highly susceptible to lightning strikes.
Wiring must comply with local codes, regulations and ordinances. Grounding may be
required to meet various approval body certification, for example CE conformity. Refer to
Appendix A of this document for details.
Figure 54. With optional devices such as remote meter, the voltage drop for these options must be
added to the basic 10.8-volt supply requirements to determine the required transmitter voltage
(V
XMTR
) and maximum loop resistance (R
LOOP MAX
). Additional consideration is required when
selecting intrinsic safety barriers to ensure that they will supply at least minimum transmitter voltage
(V
XMTR MIN
), including the required 250 ohms of resistance (typically within the barriers) needed for
digital communications.
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