Figure 7 - Transmitter 9-Screw Terminal Board And Grounding Screw - Honeywell STT850 SMARTLINE User Manual

Loop wiring is connected to the Transmitter by simply attaching the positive (+) and negative (–) loop
wires to the positive (+) and negative (–) terminals on the Transmitter terminal block in the
Electronics Housing shown in
at the power supply end.
Figure 7 – Transmitter 9-Screw Terminal Board and Grounding Screw
As shown in Figure 7, 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. Grounding the
Transmitter for proper operation is required, as 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 areas that are highly susceptible to lightning strikes. As noted above, the Loop
Power wiring shield should only be connected to earth ground at the power supply end.
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.
Note: Terminal #3 is for loop test and is not applicable for Fieldbus option.
The Transmitter is designed to operate in a two-wire power/current loop with loop resistance and
power supply voltage within the operating range; see
voltage drop for this must be added to the basic power supply voltage requirements to determine the
required Transmitter voltage (V
consideration is required when selecting intrinsic safety barriers to ensure that they will supply at
least minimum Transmitter voltage (V
(typically within the barriers) needed for digital communications.
Page 10
Figure 7. Connect the Loop Power wiring shield to earth ground only
) and maximum loop resistance (R
XMTR
), including the required 250 ohms of resistance
XMTR MIN
STT850 Temperature Transmitter User's Manual
Figure 6. With an optional remote meter, the
LOOP MAX
). Additional
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