Vega VEGAMET 862 - Screen Control

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11 Applications and functions
VEGAMET 862 • 4 … 20 mA/HART
58867-EN-200401
Thepumpcontrolsystemoersthepossibilitytochoosebetween
sequenced and alternating pump operation:
•
Sequenced operation: Depending on the switching points, all
pumps are switched on one after the other, i.e. the max. number
of pumps that can be switched on corresponds to the number of
assigned relays
•
Alternating pump operation: Independent of the switching point,
only one pump at a time is switched on
If the level does not change over a longer period of time, the same
pump would remain switched on. Via the parameter "Changeover
time", a time period can be preset, after which a forced changeover of
the pump is carried out. This function is described under pump control
1/2.
When pump control is activated, pump monitoring can also be
switched on. A return signal to the respective digital input is required
for this. The function is described under pump control 1/2.
If all pumps have the same capacity and are used for the same task
alternately, the running time should always be roughly the same. The
respective operating hours are summed up individually in the control-
ler and can be read out in the menu " Diagnosis – Switched-on time".
Ifalargedierencebetweenthepumpsisdetermined,thecapacityof
one of the pumps must have fallen considerably. This information can
be consulted for diagnosis and service, e.g. to recognize plugged-up
ltersorwornoutbearings.
Since in this case all pumps operate alternately in the same area,
theirswitch-onandswitch-opointsmustbethesame.Inaddition,
the mode "Alternating pump operation" must be active.
Note:
The index of the last switched-on relay is not saved in case of voltage
loss, this means that after the controller is switched back on again,
therelaywiththelowestindexalwaysstartsrst.
11.3 Screen control
Inthemechanicalpre-cleaningofahydropowerplant,oatingsolids
are removed with screens or sieves. The subsequent process stages
are thus protected from sedimentation, clogging or abrasion. Large
solids are screened out in the coarse screen, compressed in the
screeningpressandthendisposedof.Thenescreenremovesthe
smallerresiduesfromthewastewater.Thedierentialmeasurement
of the water level in front of and behind the screen determines the de-
gree of pollution and initiates the cleaning of the screen. Two sensors
can be connected simultaneously to the two-channel controller and
thedierentialmeasurementcanbeeasilyadjusted.Relayoutputs
can be used for calculation control and several current outputs for
signal processing.
Pump control mode
Option, forced switchover
Pump monitoring
Diagnosis via running
time
Application description