Ascon Tecnologic - e33 - OPERATING INSTRUCTIONS - PAG. 10
tor, 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 can-
not be performed until the acquisition of a new reference value.
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 system can be used to guarantee a defrost if the evapo-
rator reaches very low temperatures that normally result
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 or the thermostated
defrost mode is used (
ddy
=
Et
), the cycle length is set by
parameter
dde
.
If the Evaporator Probe (
EP
) is used and the thermostated
electric defrost is not selected (
ddy
=
EL
,
in
,
no
), the defrost
time occurs when the temperature measured by
EP
probe
exceeds the temperature at parameter
DtE
.
If this temperature is not reached in the time set in the pa-
rameter
ddE
, defrost cycle is interrupted.
To avoid unnecessary defrosting when the evaporator tem-
perature is high in modes
ddC
=
rt
,
ct
,
cS
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 param-
eters
dtS
and also
dtE
the defrosting is 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 tem-
perature 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
Lb
Shows the label
dEF
during the defrost cycle and
after the defrost until, at the end of defrost, the tempera-
ture has not reached the lock value or the value [
SP
+
rd
] or is elapsed the time set on parameter
AdA
oF
The display continues showing the temperature meas-
ured by the Pr1 probe during the defrost cycle.
