VEGA VEGAPULS 41 Profibus PA - Manual (Page 4)

4 VEGAPULS 41 – Profibus PA
27292-EN-041227
Product description
1 Product description
Radar sensors usually come with horn or rod
antennas. PTFE rod antennas are suitable for
many applications with chemically aggres-
sive products, but are unsuitable for small
vessels due to their size. Also the reception
efficiency of the rod antenna is lower than that
of the (less resistant) horn antenna. The two
new radar sensors, VEGAPULS 43 with DN
50 and DN 80 process fittings and the de-
scribed VEGAPULS 41 with 1½“ process
fitting, perfectly round out the instrument
series. Horn and rod antennas that protrude
into the vessel belong to the past. The an-
tenna of VEGAPULS 41 consists of a small
40 mm TFM-PTFE cone that is suitable for
chemically aggressive environments.
Fluorothermoplasts and perfluoroelastomers
(PTFE) have been known as the „Mercedes“
of plastic materials for many years. They are
resistant to virtually all chemical media, such
as e.g. amines, ketones, esters, acids (sul-
phuric acid, phosphoric acid, hydrochloric
acid, nitric acid), alkalis (caustic soda), oxi-
dants, fuels and oils. These plastics do not
become brittle or age and are suitable for
temperatures up to 150°C. The only limits to
these materials are applications with fluorine
under high pressure or with liquid alkali met-
als (sodium or potassium), where adverse
reactions may occur. The cone acts like a
lens that focuses short (0.15 mW) radar
pulses into a beam and sends them towards
the product. During the pulse breaks, the
cones operate like a unidirectional micro-
phone with optimum reception efficiency. The
intelligent, extremely fast electronics converts
the radar echo into a precise image of the
environment and level, which is outputted as
a 4 … 20 mA or Profibus signal. Due to their small housing dimensions and
process fittings, the compact sensors are
unobtrusive and, above all, cost-effective
monitors of your product levels. With their
integrated display, they enable high-
precision level measurements and can be
used for applications in which the
advantages of non-contact measurement
could never before be realized.
VEGAPULS radar sensors are perfectly
adapted to two-wire technology. The supply
voltage and the output signal are transmitted
via one two-wire cable. The instruments
produce an analogue 4 … 20 mA signal as
output, i.e. measuring signal.
1.1 Function
Ra dio d etecting a nd r anging: Radar.
VEGAPULS radar sensors are used for non-
contact, continuous distance measurement.
The measured distance corresponds to a
filling height and is outputted as level.
Measuring principle:
emission – reflection – reception
Extremely small 26 GHz radar signals are
emitted from the antenna of the radar sensor
as short pulses. The radar pulses reflected
by the sensor environment and the product
are received by the antenna as radar ech-
oes. The running period of the radar pulses
from emission to reception is proportional to
the distance and hence to the level.