Emerson Rosemount Smart Wireless THUM, Справочное руководство

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Reference Manual
00809-0100-4075, Rev BA
October 2010
Smart Wireless THUM Adapter
1-4
Figure 1-1. THUM Adapter
Position
Conduit Entry
When installing the THUM Adapter into the conduit entry of a wired device,
use an approved thread sealant. Thread sealant provides a water tight seal.
The thread sealant also provides a lubrication to ensure easy removal of the
THUM Adapter.
M20 Conduit Adapter
When using the M20 Conduit Adapter on the THUM Adapter, use an
approved thread sealant and tighten wrench tight to the THUM Adapter. When
installing the M20 conduit adapter into a conduit tighten to 32.5 Nm/25 ft-lb. to
ensure water tight seal.
Field Communicator Connections
In order for the Field Communicator to interface with the THUM Adapter, the
wired device must be powered. The Field Communicator must be put into poll
mode and should use the THUM Adapter address of 63.
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.
Load Resistor
If required, add a load resistor as shown in Figure 3-20, 3-22, and 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.
When adding a load resistor, ensure that uninsulated conductors do not
contact the enclosure and/or other exposed metal parts.
Loop Current THUM Adapter voltage drop
3.5 mA
25 mA 2.25 V
1.2 V