Wiring Connections And Power Up; Figure 10: Two-Wire Power/Current Loop - Honeywell ST 800 Quick Start Installation Manual

SmartLine Pressure Transmitter

WIRING CONNECTIONS AND POWER UP

Summary
The transmitter is designed to operate in a two-wire power/current loop with loop
resistance and power supply voltage within the operating range shown in Figure 10
Loop wiring is connected to the transmitter by simply attaching the positive (+) and
negative (–) loop wires to the positive (+) and negative (–) SIGNAL screw terminals
on the terminal block in the transmitter's electronics housing shown in Figure 11.
Each transmitter includes an internal terminal to connect it to earth ground. Also a
ground terminal can be optionally 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.

Figure 10: Two-wire power/current loop

December 2016 Quick Start Installation Guide 13