Figure 8: Transmitter 9-Screw Terminal Board And Grounding Screw - Honeywell STT850 Quick Start Manual

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Figure 8: Transmitter 9-Screw Terminal Board and Grounding Screw

As shown in

Figure 8,

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.

Terminal #4 is for Digital Output and is not applicable for Fieldbus option.

For HART and DE 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

Figure

With an optional remote meter, the voltage drop for this must be added to

the basic power supply voltage requirements to determine the required Transmitter

voltage and maximum loop resistance. Additional consideration is required when

selecting intrinsic safety barriers to ensure that they will supply at least minimum

Transmitter voltage, including the required 250 ohms of resistance (typically within

the barriers) needed for digital communications.

September 2017

Quick Start Installation Guide

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