VEGA VEGASON 51P…53P Profibus PA - Manual (Page 4)

4 VEGASON 51P … 53P
Product description
1 Product description
1.1 Function
Continuous level measurement with ultrasonic
sensors is based on the running time meas-
urement of ultrasonic pulses.
Measuring principle
High performance piezoceramic transducers
emit focused 70 kHz ultrasonic pulses which
are reflected by the product surface. The
measurement electronics prepares a precise
image of the environment from the reflected
ultrasonic pulses. The transducers work both
as transmitter and receiver. As receiver, the
transducers are high-sensitivity piezo micro-
phones.
emission - reflection - reception
Meas. dis-
tance
Since the speed of sound is subject to tem-
perature influence, the transducer also con-
tinuously detects the ambient temperature,
so that the level is precisely measured even
in case of varying ambient temperature.
Output signal
The level-proportional Profibus PA measuring
signal is processed and outputted com-
pletely digitally. Digital processing of the
measuring signal ensures an accuracy which
could be never reached by an analogue
measuring signal, as the digital signal is
always transmitted error-free right up to the
last decimal point.
Varying line resistances or tiny leakage cur-
rents do not influence the accuracy of digital
technology. The digital signal is always clear
and unambiguous.
The digital signal, mirroring the adjusted
measuring range of the sensor, can be modi-
fied by various parameter settings.
Display of measured values
As an option, the series 50 ultrasonic sensors
can be equipped with an indicating instru-
ment for direct, local level survey. The indi-
cating instrument shows the precise level by
means of the analogue bar graph and the
digital number value. In addition to the indica-
tion in the sensor, you can have the level
displayed with the VEGADIS 50 external
indicating instrument at a distance of up to
25 m from the sensor. The external display of
measured values operates, like the inte-
grated display, independently of the PA out-
put signal and can be modified through indi-
vidual parameter settings.
The measurement electronics precisely cal-
culates the distance between transducer and
medium from the speed of sound and the
measured running time of the emitted sound
impulse. The distance is then converted into
a level-proportional signal and, in conjunction
with the sensor parameter settings, made
available as a precise, calibrated level value.