Ascon Tecnologic - B05B - OPERATING INSTRUCTIONS - PAG. 12
the refrigerators systems.
ct
Intervals with count only the compressor opearting time.
The
di
interval is counted as the sum of the operat-
ing times of the control output (
ot
output switched ON).
Mode typically used in the positive temperature refrig-
erators system with defrost by stopping compressor.
cS
Defrost at each compressor stop. The instrument
carries out a defrost cycle at all compressor stops (i.e.
at each
ot
output deactivation), when the temperature
reaches the Set Point or however when elapses the
Defrost Interval (
di
) time. If
di
=
oF
the defrost hap-
pens only at compressor stop. This mode is used only
on particular refrigeration systems in which it is desired
to always have the evaporator at maximum efficiency
conditions at each compressor cycle.
Set the
dC
parameter to the desired mode between
rt
,
ct
or
cS
, set the desired
di
defrost interval time (the interval
between the end of a defrost and the beginning of the next
one) to enable automatic defrost at intervals.
The first defrost after Power ON can be set with parameter
Sd
.
This allows to perform the first defrost to a different interval
from
di
time.
When is requested that the instrument performs a defrost
cycle at all Power ON (as long as the conditions set in the pa-
rameter
tE
are satisfied and in the cases describe hereafetr)
program parameter
Sd
=
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.
When, instead, is requested that the instrument performs the
defrost cycles at the same time interval, set parameter
sd
=
di
.
Automatic defrost function by interval is disabled when
di
=
oF
including the first, regardless of the time set at
Sd
parameter.
Dynamic Defrost Intervals System
Note:
For this function, it is necessary to use the evaporator
probe.
By setting parameter
dC
to the desired mode (between
rt
,
ct
or
cS
) and parameter
dd
at any value, the
Dynamic De-
frost Intervals System
function becomes operative.
If
dd
=
0
the Dynamic Defrost Intervals System is disabled.
This mode allows to dynamically reduce in progress the
defrost interval counting (
di
or
Sd
if is the first defrost),
anticipating so the execution of a defrost when it was neces-
sary, in order to an algorithm that allows to notice a decrease
performances of refrigerator thermal exchange.
The algorithm allows to estimate the thermal exchange re-
duction evaluating the increase of
D
t
between
Pr1
(controlled
temperature) and
EP
evaporator probe that is stored by the
instrument in proximity of the control Set Point.
The advantage of the
Dynamic Defrost Interval
is the possibili-
ty to program a defrost interval longer than the normal one and
allow the instrument to anticipate a defrost when necessary.
If the system results correctly set, it is possible to avoid many
non necessary defrosting cycles (and therefore save energy)
that could instead happens in normal operation when, to guar-
antee the system efficiency, the interval set between 2 defrost
cycles is too short.
By parameter
dd
-
Defrost interval percentage reduction
is possible to establish the percentage of reduction of the
remaining time to start defrost when the conditions for the
reduction happen.
Setting parameter
dd
=
100
% at the first increasing of the
temperature difference between
Pr1
cell and
EP
evaporator
probes (
PR1
-
EP
> 1°) a defrost cycle starts immediately.
To operate correctly, the instrument needs a first reference
value of the temperature difference between the cell and the
evaporator probes (
PR1
and
EP
) so any variation in the active
Set Point, differential control or defrosting operation cancels that
reference with the result that the system cannot apply a time
reduction until a new reference value is made has ben acquired.
Phase
off
off
ON
0
1
2
3
Temp.
di/Sd
time to defrost Phases 0, 1
Defrost
off
off
DT0
tE
tS
Cool
ot
Defrost
dF
S1 + d
S1
Pr1
d
EP
1°
DT1
DT2
DT3
time to defrost Phase 2
time to defrost Phase 3
time
ON
ON
ON
Example
Dynamic defrost intervals system
with a reduction
dd
=
40
% and end defrost by temperature.
Defrost by evaporator temperature
The instrument starts a defrost cycle when the evaporator tem-
perature (
EP
probe) goes below the temperature programmed
at
tF
parameter for the time set at
St
. This system can be
used to guarantee a defrost if the evaporator reaches very low
temperatures that normally result symptomatic of a bad ther-
mal exchange in comparison to the normal working conditions.
Setting
tF
=
-99.9
the function is disabled.
Defrost by continuous compressor running time
The instrument start a defrost cycle when the compressor is
turned on continuously for the time set at parameter
cd
.
This function is used because the compressor continuous opera-
tion for an extended period is usually symptomatic of a bad ther-
mal exchange typically caused by the frost on the evaporator.
Setting
cd
=
oF
the function is disabled.
5.8.2
Manual defrost
To start a manual defrosting cycle, press the key
/
when
the instrument is in Normal mode and keep it pressed for
about 5 s after which, if the conditions are correct, the LED
lights up and the instrument performs a defrosting cycle.
To stop a defrosting cycle, press the key
/
and keep it
pressed for about 5 seconds during a defrost cycle.
5.8.3
Defrost ends
The duration of the defrost cycle can be timed or, using the
evaporator probe (
Pr2
configured as
EP
), at temperature
reaching.
In the event that the evaporator probe is not used the dura-
tion of the defrost cycle is set by parameter
dE
. Setting
dE
=
oF
the interval and manual defrosts are disabled.
If instead the evaporator probe is used, the defrost cycle
ends when the temperature measured by the
Ep
evaporator
probe exceeds the temperature set in the parameter
tE
.
If the
tE
temperature is not reached in the time set at pa-
rameter
dE
the defrost cycle is interrupted.
