Table of Contents
Reference Manual
00809-0100-4075
2. Ground the Remote Mount Kit per local practices.
3. Connect the THUM Adapter to the wired device using standard practices. Wire
4. Connect the THUM Adapter to the HART wired device using the
5. Close the housing cover on the HART wired device, so that metal touches metal, but
3.4
Power supply
Minimum loop load of 250 Ohms.
The THUM Adapter communicates and derives power from a standard 4-20 mA/HART loop.
The THUM Adapter causes a small voltage drop on the loop which is linear from 2.25 V at
3.5 mA to 1.2 V at 25 mA. Under fault conditions, the maximum voltage drop is 2.5 V. The
THUM Adapter will not affect the 4-20 mA signal under normal or fault conditions as long
as the loop has at least a 2.5 V margin at the maximum loop current (25 mA for a typical
4-20 mA/HART device).
Limit the power supply to 0.5 Amps maximum, and voltage to 30 Vdc.
Loop current
3.5 mA
25 mA
Emerson.com/Rosemount
Figure 3-2: Remote Mount
running from the THUM Adapter to the wired device should be shielded or in
conduit when installed in electrically noisy environments.
do not overtighten to prevent damaging the unit.
Note
Two splice connectors are included with the THUM Adapter. The first is a two
connection splice. The second is a three connection splice for use with a resistor,
if there is not enough resistance in the loop. Both of these splice connectors can
accept 14 to 22 gauge wire. See wired device reference manual for information on
the required loop resistance.
Wiring
THUM Adapter voltage drop
2.25 mA
1.2 V
Mounting
January 2023
diagrams.
17
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