Figure 15 - St 700 Standard Transmitter - 3-Screw Terminal Board And Grounding Screw - Honeywell SmartLine ST 700 User Manual

Figure 15 – ST 700 Standard Transmitter - 3-Screw Terminal Board and
As shown in Figure 15, 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.
Note: The right hand terminal is for loop test and is not applicable for the 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 Figure
With optional lightning protection and/or a 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 ) and maximum loop resistance (R
XMTR
selecting intrinsic safety barriers to ensure that they will supply at least minimum transmitter voltage
(V ), including the required 250 ohms of resistance (typically within the barriers) needed for
XMTR MIN
digital communications.
Transmitter loop parameters are as follows:
R = maximum loop resistance (barriers plus wiring) that will allow proper Transmitter
LOOP MAX
operation and is calculated as R
In this calculation:
V = 10.8V + V
XMTR MIN
Page 28
Grounding Screw
LOOP MAX
= (V
LOOP MAX SUPPLY MIN
+ V
LP SM
ST 700 SmartLine Pressure Transmitters User's Manual
14.
). Additional consideration is required when
)  21.8mA.
– V
XMTR MIN
Revision 13