Rosemount 848T, Reference Manual

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Reference Manual
00809-0100-4848, Rev AA
July 2009
Rosemount 848T Wireless
3-10
Because of resistor variances, the input must be calibrated with the resistor
installed to meet the accuracy specifications located on page A-3. For more
information on lower and upper trim procedures, see “Calibration” on page
5-2.
Grounding Practices
The transmitter operates with the housing floating or grounded. However, the
extra noise in floating systems may impact many types of readout devices. If
the signal appears noisy or erratic, grounding the transmitter at a single point
may solve the problem.
The electronics enclosure should be grounded according to local and national
installation codes. This can be accomplished via the process connection,
internal case grounding terminal, or the external grounding terminal.
Each process installation has different requirements for grounding, use the
options recommended by the facility for the specific sensor type, or begin with
the recommendations below.
Ungrounded Thermocouple, mV, and RTD/Ohm Inputs Option:
1. Connect sensor wiring shield to Terminal Screw 5 at the terminal
block. Terminal Screw 5 is internally connected to the housing.
2. Ensure the sensor wiring is electrically isolated from the transmitter
housing.
Grounded Thermocouple Option:
1. Ground the sensor wiring shield at the sensor.
2. Ensure the sensor wiring and shield is electrically isolated from the
transmitter housing and Terminal Screw 5.
Shield Ground Point
Shield Ground Point