Vega VEGAMET 841 - Flow measurement in flumes;weirs

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10 Applications and functions
VEGAMET 841 • 4 … 20 mA
58864-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.
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 – Status - Relay". 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 number 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shortestrunningtimealwaysstartsrst.
10.3 Flowmeasurementume/weir
Waste water and rainwater are often transported to the sewage treat-
mentplantinopencollectionchannels.Theowrateismeasuredat
variouspointsinthecollectionchannels.Forowmeasurementin
open waters, a constriction or a standardised channel must be used.
Thisconstrictioncreatesacertainbackwaterdependingontheow
rate.Theowratecannowbederivedfromthelevelofthisbackwater.
Thecurrentowrateisshownonthedisplayintheselectedunitof
measurement (e.g. m
3
/h).Inaddition,theowrateismadeavailable
via the current output and can thus be further processed by down-
stream devices.
Itisalsopossibletototalizetheowratebymeansofatotalizer,the
result is shown on the display (e.g. in m
3
).Inaddition,theowratecan
be output via a corresponding number of pulses on the relay/current
output(owratepulse).Asamplingpulsecanalsobecongured.
Pump control mode
Option, forced switchover
Diagnosis via running
time
Application