Emerson Rosemount 3051 Reference Manual page 35

Reference Manual
00809-0100-4001, Rev JA
Perform the following procedure to make wiring connections:
1.
2.
3.
Power supply for 4-20 mA HART
Transmitter operates on 10.5 - 42.4 Vdc. The dc power supply should provide power with less
than two percent ripple.
Note
A minimum loop resistance of 250 ohms is required to communicate with a Field
Communicator. If a single power supply is used to power more than one 3051 transmitter, the
power supply used, and circuitry common to the transmitters, should not have more than
20 ohms of impedance at 1200 Hz.
Figure 2-18. Load limitation
The Field Communicator requires a minimum loop resistance of 250
The total resistance load is the sum of the resistance of the signal leads and the load resistance
of the controller, indicator, and related pieces. Note that the resistance of intrinsic safety
barriers, if used, must be included.
See "Safety messages" on page 5
Installation
Remove the housing cover on terminal compartment side. Do not remove the cover in
explosive atmospheres when the circuit is live. Signal wiring supplies all power to the
transmitter.
a. For 4-20 mA HART output, connect the positive lead to the terminal marked (+) and
the negative lead to the terminal marked (pwr/comm -). Do not connect powered
signal wiring to the test terminals. Power could damage the test diode.
b. For 1-5 Vdc HART Low Power output, connect the positive lead to the terminal
marked (+ pwr) and the negative lead to the terminal marked (pwr -). Connect signal
lead to V / comm +.
out
Plug and seal unused conduit connection on the transmitter housing to avoid moisture
accumulation in the terminal side. Install wiring with a drip loop. Arrange the drip loop
so the bottom is lower than the conduit connections and the transmitter housing.
Maximum Loop Resistance = 43.5 * (Power Supply Voltage – 10.5)
1387
1000
500
0
10.5
for complete warning
Operating
Region
20 30
42.4
Voltage (Vdc)

for communication.
Section 2: Installation
November 2012
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