Ascon Tecnologic - X34 - OPERATING INSTRUCTIONS - PAG. 12
5.8 Defrost control
All parameters concerning the defrost control are contained
in the ]df group.
The defrost control acts on the outputs configured as ot and dF.
The type of defrost is set by the parameter d.dt:
EL With electrical heating (or by compressor stop): dur-
ing defrost, the ot output is deactivated while the output
dF is enabled. If the dF output is not used, the defrost
will take place by compressor stop;
in With hot gas or Inversion of cycle: during defrosting
both the outputs (ot and dF) are enabled;
no Without compressor output conditioning: while
defrosting, the ot output continues to operate in order to
control the temperature, also dF output is enabled.
Et With electrical heating and defrosting temperature
control: while defrosting, the ot output is deactivated
while the output dF operates as evaporator tempera-
ture control. In this mode the defrost duration is by d.de
time-out. During defrost the dF output behaves as an
heating action temperature control with Set Point = d.tE,
the differential fixed to 1°C and refers to the temperature
measured by the evaporator probe (EP). In this mode,
if the evaporator probe is not enabled or in error, the de-
frost action behaves as with EL selection (therefore the
dF output during defrost must always remain activated).
HG With hot gas in centralized systems: with this mode
it is necessary to configure 3 outputs to control Liq-
uid solenoid valve (ot output), Hot gas solenoid valve
(dF output) and suction solenoid valve (Au outputwith
configuration Fo = 3). During defrost, only the output dF
is activated, while before and after defrost the valves per-
form a sequence of timed operations described below.
5.8.1 Starting automatic defrosts
The automatic control of defrost occours:
– Defrost at defined times – “Real Time Clock Defrost” (when
peresent and enabled the RTC);
– By interval times (regular or dynamic);
– By Evaporator temperature;
– By continuous compressor running time.
In order to avoid unnecessary defrosts when the evapora-
tor temperature is high, the d.tS parameter allows to set the
temperature related to the evaporator probe (probe config-
ured as EP) under which defrosts are possible.
If the temperature measured by the EP probe is higher than
that at parameter d.tS the defrosts are inhibited.
Defrosting at defined times – “Real Time Clock Defrosts”
The coiche d.dC = cL disables the defrost at specified inter-
vals (parameters d.di and d.Sd) and enables the Real Time
Clock Defrosts programmed through parameters c.01, c.02,
c.03, c.04, c.05, c.06, c.07, c.08, c.09, c.10, c.11, c.12, c.13
and, c.14. In this mode the instrument can therefore man-
age up to a maximum of 14 daily defrost events (14 x 7 = 98
weekly defrosts with d.8).
In any case, the events can be programmed as desired even
daily according to the following settings:
d. 1 Monday;
d. 2 Tuesday;
d. 3 Wednesday;
d. 4 Thursday;
d. 5 Friday;
d. 6 Saturday;
d. 7 Sunday;
d. 8 Every day;
d. 9 Monday, Tuesday, Wednesday, Thursday, Friday;
d.10
Monday, Tuesday, Wednesday, Thursday, Friday, Saturday;
d.11 Saturday and Sunday;
d.oF No day (event disabled).
These options allow to manage the start of defrosts at differ-
ent hours for weekdays and holidays according to user needs.
For further detailed information and programming examples,
see the “Programmable events” paragraph.
Note: Remember that for “Real Time Clock Defrosts” the
user must set d.dC = cL and the internal clock must be
present and enabled.
Defrost by regular interval time
Counting mode interval and automatic defrost starts are set
through the d.dC parameter. d.dC possibe settings:
rt Intervals with counting of the total functioning time (in-
strument ON). This mode the one currently used in the
refrigerators systems;
ct Intervals with counting of the compressor function-
ing time (ot output switched ON). The d.di interval is
counted as the sum of the operating times of the control
output (ot output activated). This mode is typically used
in the positive temperature refrigerator systems with
defrost by compressor stop.
cS
Defrost at all compressor stop. The instrument carries out
a defrost cycle at each compressor stop (i.e. at each deac-
tivation of the ot output) or however at d.di defrost interval
end with counts the total function time (instrument ON). If
d.di = oF the defrost happens only when the compressor
stops. This mode is used only on particular refrigerator
systems in which the maximum evaporator efficiency con-
ditions at each compressor cycle are requested.
To enable the automatic defrost at intervals, after setting
d.dC parameter as desired (rt, ct or cS), with parameter d.di
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 d.Sd. d.Sd
allows to perform the first defrost to 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 defrost, 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 d.Sd = d.di.
Setting d.di = oF the Automatic defrost function by interval is
totally disabled (including the first, regardless to the time set at
the d.sd parameter).
Dynamic Defrost Intervals System
Note: For this function is necessary to use the evaporator probe.
Program d.dC = rt, ct or cS and set d.dd = any value (except
0) to enable the Dynamic Defrost Intervals System mode.
If d.dd = 0 the Dynamic defrost is disabled.
This mode allows to dynamically reduce the defrost interval
counting (d.di or d.Sd if is the first defrost), anticipating, when
necessary, the defrost execution, all based on an algorithm
To Next Page
Loading...
Need help?
General
