Rosemount 8750WA, Quick Installation Manual

Page: 19 / 40

Quick Installation Guide
00825-0100-4750, Rev BA
June 2009
Rosemount 8750WA
19
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TEP
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Connect 4–20 mA Loop External Power Source
The 4–20 mA output loop signal may be powered internally or externally. The default
position of the internal/external analog power switch is in the
internal position. The
user-selectable power supply switch is located on the electronics board.
Internal
The 4–20 mA analog power loop may be powered from the transmitter itself. Resistance in
the loop must be 600 ohms or less. If a HART Field Communicator or control system will be
used, it must be connected across a minimum of 250 ohms resistance in the loop.
External
HART multidrop installations require a 10–30 V DC external analog power source. If a HART
Field Communicator or control system is to be used, it must be connected across a
minimum of 250 ohms resistance in the loop.
To connect external power to the 4–20 mA loop, connect -DC to Terminal 8 and +DC to
Terminal 7.
NOTE
To connect any of the other output options (pulse output and/or digital input/output), consult
the comprehensive product manual.
Transmitter to Sensor Wiring
A single dedicated conduit run for the coil drive and electrode cables is needed between a
sensor and a remote transmitter. Bundled cables in a single conduit are likely to create
interference and noise problems in your system. Use one set of cables per conduit run.
Figure 15. Cable Preparation Detail
Cable Shield
1.00
(26)
NOTE
Dimensions are in inches (millimeters).
4750RevBAQIG.fm Page 19 Thursday, July 16, 2009 3:52 PM