Ascon Tecnologic - e34B - OPERATING INSTRUCTIONS - PAG. 10
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.
Phase
off
off
ON
0
1
2
3
Temp.
ddi/dSd
time to defrost Phases 0, 1
Defrost
off
off
DT0
dtE
dtS
Cool
ot
Defrost
dF
SP + rd
SP
Pr1
rd
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
ddd
=
40%
and end defrost by temperature.
Defrost by evaporator temperature
The instrument starts a defrost cycle when the evaporator
temperature (
EP
probe) goes below the
dtF
programmed
temperature for
dSt
programmed time.
This modality can be used to guarantee a defrost if the
evaporator reaches very low temperatures that normally re-
sult symptomatic of a bad thermal exchange in comparison
to the normal working conditions.
When
dtF
=
-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
dcd
.
This function is used because the continuous operation for an
extended period of the compressor is usually symptomatic of
a bad thermal exchange in comparison to the normal work-
ing conditions.
When
dcd
=
oF
the function is disabled.
5.8.2
Manual defrost
To start a manual defrost cycle, press the key
/ when
in Normal operation 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 defrost cycle.
To stop a defrost cycle, press the key
/ during the de-
frost and keep it pressed for about 5 seconds.
5.8.3
End of defrosts
The defrost cycle duration can be time based, or, using the
evaporator probe (configured as
EP
) when a specific tem-
perature is reached.
If the evaporator probe is not used, the cycle time is set
by parameter
ddE
(setting
ddE
=
oF
the Time-interval or
Manual defrosts are disabled).
If, on the other hand, the evaporator probe is used, the end
of defrosting occurs when the temperature measured by this
probe configured as
EP
exceeds the temperature set with
parameter
dtE
. If
dtE
temperature is not reached within the
time set at parameter
ddE
, the defrost is anyway interrupted.
To avoid unnecessary defrosting when the evaporator tem-
