Rosemount 8712, Reference Manual

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Reference Manual
00809-0100-4664, Rev BA
January 2010
Rosemount 8712
3-2
Transmitter
Apply power to your system before making the following transmitter checks.
1. Verify that the correct sensor calibration number is entered in the
transmitter. The calibration number is listed on the sensor nameplate.
2. Verify that the correct sensor line size is entered in the transmitter.
The line size value is listed on the sensor nameplate.
3. Verify that the analog range of the transmitter matches the analog
range in the control system.
4. Verify that the forced analog output of the transmitter produces the
correct output at the control system.
Sensor
Be sure that power to your system is removed before beginning sensor
checks.
1. For horizontal flow installations , ensure that the electrodes remain
covered by process fluid.
For vertical or inclined installations , ensure that the process fluid
is flowing up into the sensor to keep the electrodes covered by
process fluid.
2. Ensure that the grounding straps on the sensor are connected to
grounding rings, lining protectors, or the adjacent pipe flanges.
Improper grounding will cause erratic operation of the system.
Wiring
1. The signal wire and coil drive wire must be twisted shielded cable.
Emerson Process Management, Rosemount division. recommends
20 AWG twisted shielded cable for the electrodes and 14 AWG
twisted shielded cable for the coils.
2. The cable shield must be connected at both ends of the electrode and
coil drive cables. Connection of the shield at both ends is absolutely
necessary for proper operation.
3. The signal and coil drive wires must be separate cables, unless
Emerson Process Management specified combo cable is used.
4. The single conduit that houses both the signal and coil drive cables
should not contain any other wires.
Process Fluid
1. The process fluid conductivity should be 5 microsiemens
(5 micro mhos) per centimeter minimum.
2. The process fluid must be free of air and gasses.
3. The sensor should be full of process fluid.
Refer to Section 6 "Maintenance and Troubleshooting" for further information.
LOCAL OPERATOR
INTERFACE
The optional Local Operator Interface (LOI) provides an operator
communications center for the 8712. By using the LOI, the operator can
access any transmitter function for changing configuration parameter settings,
checking totalized values, or other functions. The LOI is integral to the
transmitter housing.