Ascon Tecnologic - e33B - OPERATING INSTRUCTIONS - PAG. 10
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-
perature is high, parameter
DtS
allows to set the temperature
related to the
EP
probe under which defrosts are possible.
Therefore, in the indicated modes, if the temperature meas-
ured by the
EP
probe is higher than the one set at parameter
dtS
and also
dtE
defrosts are inhibited.
dtE
dts
Defrost
dF
off
off
off
ON
ON
A
B
Temp.
time
C
(NO defrost)
dde
ddi/dSd
(Defrost)
ddi/dSd
ddi/dSd
ddi
(Defrost)
EP
Example: Defrost
A
ends due to reaching of temperature
dtE
, defrost
B
ends at the end of the
ddE
time as the
temperature
dtE
is not reached, defrosting
C
does not take
place as the temperature is higher than
dts
.
dtE
dts
off
off
off
off
ddi/dSd
ON
ON
ON
time
ddi
(Defrost)
dde
1°
Defrost
dF
Temp.
EP
Example of electric defrost with evaporator temperature
control: the defrost end after
ddE
programmed time. During
defrost the
dF
output switch ON/OFF to control evaporator
temperature in heating mode with set point
dtE
and 1° dif-
ferential (Hysteresis).
The active defrost is shown on the instrument display with
the lighting up of the LED .
At the end of defrosting, it is possible to delay the new com-
pressor start up (output
ot
) at the time set in parameter
dtd
to allow the evaporator to drain. During this delay, the LED
flashes to indicate the draining state.
5.8.4
Intervals and defrosts duration in case of
evaporator probe error
In event of evaporator probe error the defrosts occur at inter-
vals
dEi
and duration
dEE
.
In case an error occurs when the time remaining to the start
or the end of defrost is lower than the one normally set with
the parameters related to error probe conditions, the start or
the end takes place with the shortest time.
These functions are provided because when the
EP
evapo-
rator probe is used, the set defrost endurance time is usually
longer than necessary (the time
ddE
is a security time-out)
and in case is used the “Dynamic Intervals Defrost System”
the interval is usually set more longer than what is normally
programmed into instruments that do not have the function.
5.8.5
Display lock during Defrost
Through parameters
ddL
and
AdA
it is possible to define the
display behaviour during defrost:
on
The
ddL
parameter locks the display at the last
Pr1
temperature reading during all the defrost cycle until,
at the end of defrost, the temperature has not reached
the lock value or the value [
SP
+
rd
] or is elapsed the
time set at parameter
AdA
;
oF
The display continues showing the temperature meas-
ured by the
Pr1
probe during the defrost cycle.
