Vega VEGAMET 841, Руководство по эксплуатации

Страница: 34 / 64

34
10 Applications and functions
VEGAMET 841 • 4 … 20 mA
58864-EN-200401
To display the percentage level correctly, select under " Measurement
loop - Linearization curve " the entry " Horiz. cylindrical tank ".
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 product surfaces, it is a good idea to set a difference
(hysteresis) of 5 % between the switching points.
10.2 Pump station with pump control function
The waste water from households and industry, together with surface
water, is fed to the sewage treatment plant via an extensive network
of sewers. If the natural gradient is not sufficient, various pumping
stations are required to compensate for the differences in height. The
level measurement in the inlet shaft serves for the economic control
of the pumps. The intelligent control of several pumps can be easily
adjusted by the controller.
Linearisation
Scaling
Relay
Application description