Emerson Rosemount 5600 Series, Справочное руководство, Страница: 12 / 128

12
Reference Manual
00809-0100-4024, Rev CA
Introduction
March 2020
Introduction
The Rosemount 5600 Series Radar Level Transmitter sends a microwave signal with a continuously
varying frequency towards the product surface. When the reflected signal returns to the antenna, it is
mixed with the outgoing signal.
Since the transmitter continuously changes the frequency of the transmitted signal, there will be a
difference in frequency between the transmitted and the reflected signals.
The transmitter mixes the two signals, resulting in a low frequency signal that is proportional to the
distance to the product surface. This signal can be measured very accurately allowing fast, reliable, and
accurate level measurements.
The Rosemount 5600 Series Radar Level Transmitter uses micro frequency to reduce sensitivity to vapor,
foam, and contamination of the antenna, and keeps the radar beam narrow in order to minimize
influence from walls and disturbing objects.
The Rosemount 5600 Series Radar Level Transmitter uses Fast Fourier Transformation (FFT), which is a
well established signal processing technique, to obtain a frequency spectrum of all echoes in the tank.
From this frequency spectrum the surface level is extracted. In combination with the echofixer, FFT
allows measurements in tanks with agitators, mixers and other disturbing objects. The echofixer
provides a technique to adapt measurements to various situations, by using information from previous
measurements.
1.3 Specific FCC requirements (USA only)
This device complies with part 15 of the FCC Rules. Operation is subject to the following two conditions:
(1) This device may not cause harmful interference, and (2) this device must accept any interference
received, including interference that may cause undesired operation.
The Rosemount 5600 generates and uses radio frequency energy. If it is not installed and used properly
(in strict accordance with the manufacturer’s instructions) it may violate FCC regulations on radio
frequency emission.
Installation on non-metallic tanks, tanks with open manholes, external-floating-roof tanks without
stillpipes etc. are not covered by this certificate, and require a Part 90 site-license. If you have an
installation like this, contact your local Emerson Automation Solutions representative for help with the
necessary license application.
1.3.1 Measuring range
The diagrams below show how the measuring range is influenced by the antenna type, dielectric
constant of the liquid (

r
) and the process conditions. For optimum performance the maximum
measuring distance should be kept within the range indicated with darker color in the diagrams. Values
are valid for free propagation measurement without still pipes (bridles).
For liquids with

r
that are smaller than 1.9 such as liquefied gases, an 8 in. (203 mm) or bigger diameter
antenna is recommended if measurement is done with free propagation. In this case the measuring
range in calm surface tanks is in typical cases 50 ft. (15 m).
To increase the measuring range further in turbulent tanks, a still pipe can be used. For still pipe
mounted Rosemount 5600 transmitters the typical measuring range is 115-160 ft. (35-50 m) in
turbulent tanks with liquids having

r
less than 1.9.