Emerson Smart Wireless THUM Adapter, Справочное руководство

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15
Reference Manual
00809-0100-4075, Rev CA
Section 3: Mounting
March 2014
Mounting
3.2.2 Remote mount
1. Install the HART device according to standard installation practices, being sure to use
an approved thread sealant on all connections.
2. The THUM Adapter should be mounted as shown in Figure 3-2 on page 14 .
3. Connect the THUM Adapter to the wired device using standard practices. Wire running
from the THUM Adapter to the wired device must be shielded or in conduit.
4. Ground the Remote Mount Kit per local practices.
5. Connect the THUM Adapter to the HART wired device using the wiring diagrams below.
See
Figure 3-19 through Figure 3-26 on the following pages.
6. Close the housing cover on the HART wired device, so that metal touches metal, but do
not over tighten 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.
3.2.3 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 55 Vdc.
3.2.4 Load resistor
If required, add a load resistor as shown in Figure 3-20 , Figure 3-22 , and Figure 3-24 . The
resistor should be adequately rated for the application (1W minimum) and be compatible with
the supplied splice connector which accepts wire sizes from 14 to 22 AWG.
Loop Current THUM Adapter voltage drop
3.5 mA 2.25 V
25 mA 1.2 V