Ascon Tecnologic - Y39 Line - Operating Instructions - Pag. 8
Third control (parameter
P.P3
) inhibits the activation of the
ot
output by a time delay (
P.P3
) that starts when the output was
turned ON last time (delay between switching-ONs).
SP
Out
ot
off
off
off
ON
ON
ON
time
P.P3
P.P3
P.P3
r.d
Pr1
Temp.
During the output inhibition the LED
OUT
(Cool
or Heat
)
blinks. It is also possible to prevent activation of all the outputs
after the instrument is turned ON, for the time set with param-
eter
P.od
.
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 that the instrument must carry out is set
with parameter
d.dt
that can be programmed as:
EL
With
electrical heating
(or by
stopping compres-
sor
): during defrost, the output
ot
is deactivated while
the output
dF
is enabled. The defrost will be made by
Stopping compressor when
dF
output is not used;
in
With
hot gas
or
inversion of cycle
: during defrost the
outputs
ot
and
dF
are enabled;
no
Without compressor output conditioning
: during
defrost, the output
ot
continues operating in order to
control the temperature while
df
output is enabled.
Et
With
electrical heating
and
defrost temperature
control
: during defrost, the
ot
output is deactive while
df
output operates as evaporator temperature control.
With this selection, the defrost end is always timed (time
d.dE
).
During defrost
dF
output behaves as an heating action tem-
perature control with Set Point =
d.tE
, fixed differential at 1°C
and operates using as reference the reading of the evaporator
temperature probe (
EP
).
5.8.1 Automatic Defrosts Start
The automatic control of defrost occours by interval times.
The automatic defrost is therefore obtained by setting, with
d.di
parameter, the time that must elapse between the end
of a defrost and the beginning of the next one.
The first defrost after Power ON can be set with parameter
d.Sd
. This allows to perform the first defrost at a different
interval from
d.di
time.
To force the instrument to perform a defrost cycle at each
power ON (as long as the conditions set with parameters
d.tS
and
d.tE
are satisfied) set parameter
d.Sd
=
oF
.
This allows the evaporator to be permanently defrosted,
even when frequent power supply interruptions occur that
may stop several defrost cycles.
If, on the other hand, all defrosts must be executed at the
same interval time, set
d.Sd
=
d.di
.
Setting
d.di
=
oF
interval defrosts are disabled (including
the first one, regardless of the time set at
d.Sd
parameter).
Counting mode interval and automatic defrost start modes
are set with parameter
d.dC
:
rt
At real-time power-ON intervals.
d.di
interval is count-
ed referring to the total time the instrument is switched
ON. Mode currently used in the refrigerators systems.
ct
At time intervals of the compressor operation (output
ot
switched ON). Mode typically used in the posi-
tive temperature refrigerators systems with defrost by
stopping compressor.
cS
Defrost cycle at each compressor stop (i.e. at each
deactivation of the output
ot
) or however at defrost
interval end with counts the total working time (instru-
ment ON). If
d.di
=
oF
the defrost happens only at
compressor stops. This mode is used only on particu-
lar refrigerator systems in which is needed to have the
evaporator at the maximum efficiency conditions at all
compressor cycles.
St
Defrost due to evaporator temperature. The instru-
ment starts a defrost cycle when the temperature
evaporator (
EP
probe) goes below the
d.tS
pro-
grammed temperature or however at defrost interval
end as for the
rt
mode (instrument
ON
). If
d.di
=
oF
the defrost happens only when the evaporator tem-
perature goes below the one set at
d.tS
. This metod
can be used in heat pump defrost systems (in this
case the defrost intervals are usually disabled) or to
guarantee a defrost if the evaporator reaches very
low temperatures that normally result symptomatic of
a bad thermal exchange in comparison to the normal
working conditions.
dd
Dynamic defrost intervals system. This mode allows
to dynamically reduce the defrost interval counting in
progress (
d.di
or
d.Sd
if it is the first defrost), anticipat-
ing the execution of a defrost when necessary, follow-
ing an algorithm that allows to notice a performance
decreasing of refrigerator thermal exchange. Besides
it maintains active the mode
St
that allows a further
control of the defrost in order to notice a performance
decreasing of refrigerator thermal exchange.
The algorithm allows to esteem a reduction of thermal
exchange in base to the increase of the difference of
temperature between
Pr1
(controlled temperature)
and evaporator (
EP
probe) that is stored by the instru-
ment in proximity of the Set Point.
The advantage of the “
Dynamic Defrost Interval
” is the
possibility to program a defrost interval time longer
than normal. The instrument has the possibility to
anticipate the defrost when necessary or to start the
cycle after the programmed time.
If the
DDI
is correctly set many un-necessary defrost cy-
cles can be avoided (obtaining an energy saving) which
instead can happen, in the normal operation when, to
guarantee with greater certainty the system efficiency,
the defrost interval is programmed at a too low time.
Phase
off
off
ON
ON
0
1
2
3
Temp.
time
d.di/d.Sd
time to defrost Phases 0, 1
Defrost
ON
ON
off
off
DT0
d.tE
d.tS
Cool
(ot)
dF
SP
+ r.d
SP
PR1
r.d
EP
1°
DT1
DT2
DT3
time to defrost Phase 2
time to defrost Phase 3
