Ascon Tecnologic - e33B - OPERATING INSTRUCTIONS - PAG. 9
eter
Pod
.
During the power ON delay phase, the display shows the
indication
od
alternated with the normal visualization.
All these functions are disabled if the relative parameters are
set to
OFF
(
oF
).
5.8
Defrost control
The defrost control acts on the outputs configured as
ot
and
dF
.
The type of defrost is set by the parameter
ddt
:
EL
With electrical heating
(or
By stopping compres-
sor
): while defrosting, the output
ot
is deactivated
while the output
dF
is enabled. The defrost will be by
Stopping compressor if not using the
dF
output;
in
With hot gas
or
Cycle inversion
: while defrosting
both the
ot
and
dF
outputs are enabled:
no
Without compressor output conditioning
: while de-
frosting, the output
ot
continuous to operate in order to
control thetemperature, also the output
dF
is enabled;
Et
With electrical heating and defrosting temperature
control
: during defrosting, the output
ot
is deactivated
while the output
dF
operate as evaporator temperature
control. In this mode the defrost lenght is by time-out
(time
ddE
). During the defrost, the
dF
output behaves
as an heating mode control with Set Point =
dtE
, dif-
ferential fixed at 1°C and operates with the values of
the
EP
evaporator probe. In this functioning mode, if
the evaporator probe is not enabled or is in error, the
defrost behaves as with selection
EL
(therefore the
output
dF
during defrost must always be active).
5.8.1
Starting automatic defrosts
The automatic control of defrost occours:
–
By interval times (regular or dynamic);
–
By Evaporator temperature;
–
By continuous compressor running time.
In order to avoid unnecessary defrosting when the evapora-
tor temperature is high the
dtS
parameter allows to set the
temperature related to the evaporator probe (probe config-
ured as
EP
) under which defrosts are possible.
Therefore, in the modes indicated, if the temperature meas-
ured by the evaporator probe is higher than the temperature
set with
dtS
parameter, defrosts are inhibited.
Defrost by regular interval time
As an alternative to programmable defrosts, the instrument
allows to execute the defrosts at programmed interval time.
Through the
ddC
parameter, can be set the defrost interval
counting mode:
rt
At real-time power-ON intervals. The
ddi
interval is
counted as the total ignition time of the instrument.
This mode is the one currently used in the refrigera-
tion systems.
ct
At time intervals of the compressor operation. The
ddi
interval is counted as the sum of the operating
times of the
ot
output (
ot
output activated). This mode
is usually used in refrigeration systems with compres-
sor stop defrosting.
cS
Defrost cycle at each compressor stop. The instrument
starts a defrost cycle every time the
ot
output is deac-
tivated, when the Set Point is reached or at the expira-
tion of the interval set with
ddi
paramreter. If
ddi
=
oF
the defrost happens only at compressor stop.
This mode is used only on particular refrigerating ma-
chines in which is required the maximum evaporator
efficiency at each compressor cycle.
To enable automatic defrost at intervals, after setting the
ddC
parameter as desired between
rt
,
ct
or
cS
, with the ddi pa-
rameter select the time interval between the end of a defrost
and the beginning of the next.
The time that the instrument must wait to perform the first
defrost after power ON can be set with parameter
dSd
. This
allows to perform the first defrost to a different interval from
ddi
time.
To force the instrument to perform a defrost cycle at each
power ON (as long as the conditions set with parameters
dtS
and
dtE
are satisfied) set parameter
dSd
=
oF
.
This allows the evaporator to be permanently defrosted,
even when frequent interruptions to power supply occur that
may cause the cancellation of the various defrosting cycles.
If instead it is desired that all the defrosts are performed at
the same interval time, set
dSd
=
ddi
.
Setting
ddi
=
oF the
Automatic defrost function by interval
is totally disabled (including the first, regardless of the time
set to the
dsd
parameter).
Dynamic Defrost Intervals System
Note:
For this function is necessary to use the evaporator
probe.
To enable the
Dynamic Defrost Intervals System
, program
ddC
=
rt
,
ct
or
cS
and set
ddd
=
any value
.
Setting
ddd
=
0
, the defrost intervals are those set by the user
and the
Dynamic Defrost Intervals System
is disabled.
This mode allows to dynamically reduce the defrost interval
counting (
ddi
or
dSd
if is the first defrost), anticipating, when
necessary, the defrost execution, all based on an algorithm that
detects a drop in the refrigerator thermal exchange performance.
The algorithm estimates a reduction in thermal exchange
based on the increase in temperature difference between
Pr1
(cell control) and evaporator probe (probe configured as
EP
). The result is stored by the instrument when the tem-
perature is close to the Set Point setting.
The advantage of the
Dynamic Defrost Interval
is the pos-
sibility to program a defrost interval time longer than normal,
so, when necessary, the instrument has the possibility to
anticipate the defrost.
If the system results correctly set, it is possible to avoid
many unnecessary defrosting cycles (and therefore to obtain
aconsistent energy saving) that may occur with normal op-
eration when, to ensure more system efficiency, the defrost-
ing interval is programmed with a time that is often too short.
With the parameter
ddd
-
Defrost interval percentage reduc-
tion
is possible to establish the percentage of reduction of
the remaining time to start defrost when the conditions for
the reduction happen.
Setting
ddd
=
100%
at the first increase of the stored tem-
perature difference (
> 1°
) between cell (
Pr1
) and evaporator
(
EP
) probes a defrost starts immediately.
For correct functioning the instrument needs a first refer-
ence value of the temperature difference between cell and
evaporator, in this way all variations to the Active Set Point
value, to the differential
rd
, the start of a continuous cycle
or a defrost execution deletes this reference value and any
reduction cannot be performed until the acquisition of a new
reference value.