Ascon Tecnologic - e33B - OPERATING INSTRUCTIONS - PAG. 10
Phase
off off
ON
01 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
offoffoff
ON ON
AB
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
offoffoff 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.
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