Emerson Rosemount 3051S Series, Reference Manual

Page: 31 / 240

Reference Manual
00809-0100-4801, Rev FA
October 2010
2-17
Rosemount 3051S Series
Signal Wiring Grounding
Do not run signal wiring in conduit or open trays with power wiring, or near
heavy electrical equipment. Grounding terminations are provided on the
sensor module and inside the Terminal Compartment. These grounds are
used when transient protect terminal blocks are installed or to fulfill local
regulations. See Step 2 below for more information on how the cable shield
should be grounded.
1. Remove the Field Terminals housing cover.
2. Connect the wiring pair and ground as indicated in Figure 2-9.
a. The terminals are not polarity sensitive.
b. The cable shield should:
• Be trimmed close and insulated from touching the transmitter
housing.
• Continuously connect to the termination point.
• Be connected to a good earth ground at the power supply end.
Figure 2-9. Wiring
3. Replace the housing cover. It is recommended that the cover be
tightened until there is no gap between the cover and the housing.
4. Plug and seal unused conduit connections.
Power Supply 4–20 mA Transmitters
The dc power supply should provide power with less than two percent ripple.
Total resistance load is the sum of resistance from 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 “Load Limitations” on page A-7.
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
3051S transmitter, the power supply used, and circuitry common to the
transmitters, should not have more than 20 ohms of impedance at 1200 Hz.
DP
Trim shield and
insulate
Insulate
Shield
Connect Shield Back to the
Power Supply Ground
Ground for
Transient
Protection
Minimize
Distance
Minimize
Distance