Vega VEGAMET 341, Руководство по эксплуатации

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10 Applications and functions
VEGAMET 341 • 4 … 20 mA
63730-EN-210616
priate reference value (" Percent, Lin.-percent, Scaled ") as well as
the behaviour in case of failure (" Switching status OFF, hold value ").
Finally, assign the values for the upper and lower switching point.
Configure measured value indication
In the last step you can configure which and how many measured
values are to be shown on the display. In addition, you can define
the base of the display value, the display format and the optional bar
graph.
10.1.2 Application example
A horizontal cylindrical tank has a capacity of 10000 litres. The
measurement is carried out with a level sensor operating according to
the guided microwave principle. The filling by a tank car is controlled
via relay 1 and a valve (overfill protection). The discharge is carried
out via a pump and is controlled by relay 2 (dry run protection). The
max. volume should be at 90 % level, this means 9475 litres with a
standard vessel. The min. level should be set to 5 %, this corresponds
to 194 litres. The volume is to be displayed in litres.
To display the percentage level correctly, select under " Measurement
loop - Linearization curve " the entry " Horiz. cylindrical tank ".
Carry out the adjustment in the controller as described in chapter "
Setup steps ". No further adjustment may be carried out in the sensor
itself. For the max. adjustment, fill the vessel up to the requested max.
level and accept the actually measured value. If this is not possible,
the corresponding sensor value can also be entered. For the min.
adjustment, empty the vessel down to the min. level or enter the cor-
responding sensor value.
To display the volume in litres, you have to enter " Volume " as the unit
in litres under " Measurement loop - Scaling ". The allocation is then
carried out, in this example 100 %
≙
10000 litres and 0 %
≙
0 litres.
Percent is selected as reference value for the relays. The mode of
relay 1 is set to overfill protection, relay 2 must be activated and gets
mode dry run protection. To ensure that the pump switches off in case
of failure, the reaction in case of failure should be set to switching
status OFF. The switching points are set as follows:
•
Relay 1:
Switch-off point 90 %, switch-on point 85 %
•
Relay 2:
Switch-off point 5 %, switch-on point 10 %
Information:
The switch-on and switch-off point of the relays must not be set to the
same switching point because this would cause a continuous switch-
ing on and off when this threshold is reached. To avoid this effect also
with fluctuating medium surfaces, it is a good idea to set a difference
(hysteresis) of 5 % between the switching points.
Description
Linearisation
Adjustment
Scaling
Relay