dixell xweb 5000, Operation Manual, Page: 76 / 115

XWEB5000 Operation Manual
76/115 1592010600
3.4.6.1 INTERPRETING THE %COOL
From an ideal point of view the highest the percentage is, the better the compressor rack has been tuned.
Of course if many devices work with a percentage next to 100% it means that quite probably during the
worst condition case some devices may fail to receive the correct amount of cooling. Use the data
provided by “Performance meter” according to your experience. This software tool can be useful also
when the majority of the devices (belonging to the same typology) work within a certain range and only
one reports a different value. Quite probably that one is not working properly.
3.5 SUPERVISING MENU
3.5.1 SUPERVISING (*
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)
The concept of the supervising expands the possibility to completely manage the installations.
Supervising means the possibility for XWEB to interact in a self-sufficient mode with the devices connected.
To simplify this concept the user could think about a logical block, where the inputs are the values monitored
by the XWEB (temperature, pressure, status,
etc…) and as outputs there is the possibility to send a set of
commands to specific controllers. The logical link between input and output is the supervising, in other word
an algorithm programmed by the user and implement by the system.
The fundamental link between input and output is exactly the supervision, that is a special algorithm
programmed by the user and that the system put in practice every time that input values satisfy criterions that
are set up.
Watch out that the algorithm doesn‟t send the complementary commands when the inputs are
triggered off. It means that the user after programming the direct action (e.g. a setpoint increment), later on he
must also program the reverse action (e.g. a setpoint decrement).
In other words, when the user think and do a direct action, has to take care of the realization of the
opposite action, otherwise the system will not restore the initial conditions when they are required.
Considering the importance of this new working device, Dixell has tried to make this as simple as it is possible
in order to help the final user. For this reason the programming phase is realized through a graphic user
interface, so it
isn‟t necessary (unlike in a normal programming language for PLC) to have any knowledge in
programming.
3.5.1.1 THE PROJECT
From the practical point of view, the user must know in advance the supervisor project that he wants to
realize, so for didactic purpose, all the chapter treats this project: the installation needs to monitor the
emergency generator working status that is active only without main electric power. In this state, the
supervisor have to send several commands to the controllers in order to manage at best the energy saving
during electric black-out status. In this example the generator is monitored by a Dixell XJA50D controller
(acquisition module alarm/status). At start up of the generator, the XJA50D signals it by means of a variation
of the corresponding digital input. During emergency generator functioning mode the XWEB has to send an
“energy saving” command (working set point variation) and, only for compatible controllers, also the command
for the
“saving cool”, blinds down.
3.5.1.2 SDC, ELS E ODC
Every project is composed of 3 distinct blocks:

SDC (source device class) is the set of controllers whose
values (probe values, working status, etc…)
are the input of the supervision project.

ELS (event logic supervisor) functional block joins the SDC input with the output, in other word the
command sent to controllers that are supervised.

ODC (object device class) is the device class that send commands
It is possible to add other functional blocks, for instance STE (system time event). Others will be added by
Dixell during the XWEB development.
3.5.1.3 SDC
Select “Create” menu. A SDC will be created and it will verify the digital input status of the XJA50 module.
When the input is active for almost 3 minutes, also the generator will be considered active.
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(*) Functionality not available with XWEB5000-6AA00