Considerations; General; Commissioning; Mechanical - Emerson Rosemount 248 Reference Manual

Reference Manual
00809-0100-4825, Rev CB
Refer to the following literature for sensors, thermowells, and extensions that form a complete
point solution with the Rosemount 248:
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1.3

Considerations

1.3.1

General

Electrical temperature sensors, such as RTDs and thermocouples, produce low-level signals
proportional to the sensed temperature. The Rosemount 248 converts the low-level sensor
signal to a standard 4–20 mA dc signal that is relatively insensitive to lead length and electrical
noise. This current signal is transmitted to the control room through two wires.
1.3.2

Commissioning

The transmitter may be commissioned before or after installation. It can be useful to
commission it on the bench, before installation, to ensure proper operation and to become
familiar with its functionality. The instruments in the loop should be installed according to the
intrinsically safe or non-incendive field wiring practices before connecting a Field
Communicator in an explosive atmosphere. For more information, see
page
1.3.3

Mechanical

Location
When choosing an installation location, take into account access to the transmitter.
Special mounting
Special hardware is available for mounting a Rosemount 248 head mount transmitter to a DIN
rail.
1.3.4

Electrical

Proper electrical installation is necessary to prevent errors from sensor lead resistance and
electrical noise. For best results, shielded cable should be used in electrically noisy
environments. A resistance between 250 and 1100 ohms must be present in the loop for
communication with a Field Communicator.
Make wiring connections through the cable entry in the side of the connection head being sure
to provide adequate clearance for cover removal.
Introduction
Temperature Sensors and Assemblies Product Data Sheet, Volume 1 (Document No.
00813-0100-2654)
Temperature Sensors and Assemblies Product Data Sheet, Volume 2 (Document No.
00813-0200-2654)
Temperature sensors and Assemblies Product Data Sheet, Volume 3 (Document No.
00813-0301-2654)
24.
Section 1: Introduction
March 2014
"Commissioning" on
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