Emerson Rosemount 2090P Reference Manual page 29

Reference Manual
00809-0100-4690, Rev FC
June 2011
Wiring
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Do not connect the power signal wiring to the test terminals. Voltage may burn out
the reverse-polarity protection diode in the test connection.
NOTE
Use shielded twisted pairs to yield best results. To ensure proper
communication, use 24 AWG or larger wire, and do not exceed 5000 feet
(1500 meters).
All power to the transmitter is supplied over the signal wiring. Signal wiring
need not be shielded, but use twisted pairs for best results. Do not run
unshielded signal wiring in conduit or open trays with power wiring, or near
heavy electrical equipment. For high EMI/RFI environments, shielded twisted
pair cable should be used. To power the transmitter, connect the positive
power lead to the terminal marked "PWR/COMM+" and the negative power
lead to the terminal marked "–" (see Figure 2-11). Tighten the terminal screws
to ensure that proper contact is made. Avoid contact with the leads and the
terminals. No additional power wiring is required for transmitters with "S"
output. For "N" output code transmitters, connect positive signal lead to "test
+" and negative signal lead to terminal marked "-."
To connect test equipment for monitoring the output of the Rosemount
2088/2090 transmitter during maintenance procedures, connect one lead to
the terminal labeled "TEST+" and the other lead to the terminal labeled "–"
(see Figure 2-11). Avoid contact with the leads and the terminals.
Signal wiring may be grounded at any one point on the measurement loop, or
it may be left ungrounded. The negative side of the power supply is a
recommended grounding point. The transmitter case may be grounded or left
ungrounded.
Conduit connections at the transmitter should be sealed to prevent moisture
accumulating in the field terminal side of the transmitter housing. Also, install
wiring with a drip loop with the bottom of the drip loop lower than the conduit
connection of the transmitter housing.
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