Figure 18 Ground Connection For Lightning Protection - Honeywell ST 3000 User Manual

4.4 Wiring ST 3000 Transmitter,
Approval body
requirements
Lightning protection
46 ST 3000 Release 300 and SFC Model STS103 User's Manual
If your transmitter was ordered with Table III option 3N for self-
declared approval per 94/9/EC (ATEX4), you must use a power supply
that includes a voltage limiting device that will keep the voltage to the
transmitter from exceeding 42 Vdc. You can achieve this by using a
battery as the supply or one of these voltage limiting means.
 Double wound mains transformer per BS 3535 or equivalent.
 An adequately rated zener diode whose voltage is not significantly
higher than the rated voltage.
 An adequately rated semiconductor voltage regulator.
When your transmitter is equipped with optional lightning protection,
you must connect a wire from the transmitter to ground as shown in
Figure 18 to make the protection effective. We recommend that you use
a size 8 AWG (American Wire Gage) or (8.37mm
covered wire.
Figure 18 Ground Connection for Lightning Protection.
Continued
2
) bare or green
Electronics
Housing
Connect to
Earth Ground
Continued on next page
February 2012