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meters in the field and when a valve is commanded to open there will be no flow of water or
fertilizer. However at the simulation, we can get a similar effect if we activate
Configuration/Flow-simulation at the menu bar. The software will simulate the flow of water
meters according to the specified nominal flow of the valves opened under each water meter.
Free water meters will therefore not get flow simulation because they got no valves belonging
to them.
The DREAM simulation may also be used for defining a new configuration that can be saved in
a configuration file that can later be loaded into the DREAM controller.
9.
SUPPLEMENTARY DEVICES
In this chapter we shall describe some devices that are used in the DREAM 2 system in special
cases.
9.1
Switching electric pumps
Naturally, the switching of electric devices differs from the opening and closing of hydraulic
valves, the switching process is involved with connecting/disconnecting high power electric
sources to high power loads, this action may sometimes create sparks and electric
interferences, therefore it is better to have a good galvanic isolation between the commanding
unit and the high power electric devices being switched. This is the reason why we are using
special
PUMP- SWITCHING UNITS
that contain a solid state relay in which the connection
between the input and the output is optical, therefore they supply good galvanic isolation.
We are using several types of
PUMP-SWITCHING UNITS
that differ by the type of command
they are ready to accept and the type of load they can switch.
SWITCHING
UNIT TYPE
TYPE OF
COMMAND
TYPE OF
LOAD
REMARKS
AC/AC
24v AC
Single phase
240v AC 25A
1.
May require a capacitor of 1µF 400v
in parallel with the load when the
load refuses to turn OFF.
DC/AC
12v DC latch
Single phase
240v AC 25A
1.
May require a capacitor of 1µF 400v
in parallel with the load when the
load refuses to turn OFF.
2.
Requires supply of 12v DC
DC/DC
12v DC latch
200v DC
1.
Requires supply of 12v DC
