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Quick Start Guide
3
December 2014
Overview of the Rosemount 3107 and 3108
The Rosemount 3107 and 3108 are sealed 4–20 mA loop-powered liquid level
transmitters, specifically designed for use in waste water and effluent treatment plant
on aqueous applications.
These rugged UPVC transmitters are certified Intrinsically Safe for use in Zone 0 areas,
and factory fitted with up to 165 ft. (50 m) of two-core cable for simple low cost
installation in sumps, wet-wells and over open channel flow structures.
The transmitter may be mounted in a hazardous area if powered from a protected
power supply. They can be connected directly to a plant control system, or used with a
Rosemount 3490 Series Control Unit for programmable control functionality.
Theory of operation
Each transmitter is designed to be mounted above a liquid, and uses ultrasonic pulses
to continuously measure the distance to the liquid surface. The
microprocessor-controlled electronics calculates distance to the liquid level from the
time delay between the transmitting and receiving of signals.
When programmed with the bottom reference of the application – usually the bottom
of a tank – the transmitter will calculate the liquid depth (level), and output the level
(Figure 1) as a 4–20 mA signal and a digital HART® signal.
The 3107 and the 3108 can also calculate contents (volume) or open channel flow, and
then output the result as a 4–20 mA signal and a digital HART signal.
Programming is achieved by remote communication using HART.
Figure 1. Typical application
A. Rosemount 3108 Flow Transmitter E. Pump
B. Rosemount 3490 Series Control Unit F. Transmitter Bottom Reference
C. 4–20 mA signal output G. 4–20 mA and HART signal input
D. Relay
B
A
G
E
E
20mA
4mA
C
F
D
D