For correct functioning the instrument needs a first reference value
of the temperature difference between cell and evaporator.
Every variation of the value of the Active Set Point, of the differen-
tial "r.d", the start of a continuous cycle or the a defrost execution
delete this reference value and any reduction will be performed un-
til the acquisition of a new reference value.
Pr1
Temp.
time
EP
SP
r.d
off
ON
Cool
(ot)
SP+r.d
DT0
DT1
1 °
DT2
DT3
ON
ON
ON
off
off
d.tE
d.di / d.Sd
Defrost
(dF)
Phase
0
1
2
3
time to defrost Ph. 0, 1
time to defrost Ph. 2
time to defrost Ph. 3
Defrost
d.tS
Example “dynamic defrost intervals system” with a reduction “d.dd”
= 40 % and end defrost by temperature.
4.8.2- MANUAL DEFROST
To start up a manual defrosting cycle, press the key UP/DEFROST
when it is not in programming mode and keep it pressed for about
5 seconds after which, if the conditions are correct, the led Defrost
will light up and the instrument will carry out a defrosting cycle.
To stop a defrosting cycle, press the key UP/DEFROST during a
defrost cycle and keep it pressed for about 5 sec.
The start up or switch off commands of a defrosting cycle can also
be given by the digital input that are correctly programmed (see Di-
gital input).
4.8.3 - DEFROST ENDS
The automatic defrosting cycle can be ended by time or, if an
evaporator probe is used (“EP” probe), when a temperature on the
evaporator is reached.
If the evaporator probe is not used or it is program the defrost
temperature control (par. “d.dy” = Et) the duration cycle is set by
the parameter
“d.dE”.
If instead the evaporator probe is used it is not program the defrost
temperature control (par. “d.dy” = EL, in, no) the defrost cycle end
when the temperature measured by the evaporator probe exceeds
the temperature set in the parameter
“d.tE”.
If this temperature is not reached in the time set in the parameter
“d.dE”, defrosting is interrupted.
d.di
Temp.
dF
d.di/dSd
off
d.tS
d.tE
ON
A
off
EP
d.di
ON
d.dE
B
(NO defrost)
d.di
off
C
time
Examples:
defrosting A ends due to reaching of temperature “dtE”,
defrosting B ends at the end of the “d.dE” time as the temperature
“d.tE” is not reached, defrosting C does not take place as the
temperature is higher than “d.tS”.
In order to avoid pointless defrosting the parameter
“d.tS”
in
“d.dC” = rt, ct, cS mode is foreseen that sets the enablement
temperature for defrosting
If the temperature measured by the probe is higher than the one
set in the parameter “d.tS” and in the parameter "d.tE" the
defrosting is inhibited.
d .d i/d .S d
d .tE
d .tS
d F
o ff
O N
o ff
T e m p .
E P
1 °
tim e
d .d E
d .d i
O N
O N
Example of electric defrost with evaporator temperature control:
The defrost end after "d.dE" programmed time. During defrost the
“dF” output switch on/off to control evaporator temperature in
heating mode with set point “d.tE” and 1° differential (Hysteresis).
The active defrost is shown on the instrument display with the
lighting up of the DEFROST led
At the end of defrosting, it is possible to delay the new start up of
the compressor (output “ot”) at the time set in parameter
“d.td”
to
allow the evaporator to drain.
During this delay, the led Defrost flashes to indicate the draining
state.
4.8.4 - DEFROST DISPLAY LOCK
Through par.
“d.dL”
and
“A.dA”
it’s possible to define the display
behaviour during defrost.
The “d.dL” parameter pemits the display visualization lock on the
last Pr1 emperature reading (“d.dL” = on) during all the defrost
cycle until, at the end of defrost, the temperature has not reached
the lock value or the value [”SP” + “r.d”] or is elapsed the time
setted on par. "A.dA".
Or it permits only the visualization of label
“dEF”
(“d.dL” = Lb)
during the defrost cycle and, after the defrost, of label
“PdF”
until,
at the end of defrost, the Pr1 temperature has not reached the lock
value or the value [”SP” + “r.d”] or is elapsed the time setted on
par. "A.dA".
The display will otherwise (“d.dL”= oF) continue to visualize the
Pr1 temperature measured by the probe during the defrost cycle.
4.9 - EVAPORATOR FANS CONTROL
The control of the fans on the output configured as “Fn” depending
on determined control statuses of the instrument and the
temperature measured by the evaporator probe (E P).
In the case that the evaporator probe is not used or in error , the
output Fn is activated only depending on the parameters “F.tn”,
“F.tF” and “F.FE”.
The parameters
“F.tn”
e
“F.tF”
decides the funs functioning when
the output configured as “ot” (compressor) is off.
When output “ot” is off , it is possible to set the instrument so that
that the output “Fn”continues to work in cycles according to the
times programmed in the parameter
“F.tn”
(fan activation time)
and
“F.tF”
(fan deactivation time).
When output “ot” is switched off the instrument activates the output
“Fn for the time “F.tn”, then deactivates it for the time “F.tF” and so
on whilst the otuput “ot” remains off.
Programming “F.tn” = oF the output “Fn” in “ot” off condition will
remain switched off.
Programming instead “F.tn” to any value and “F.tF” = oF the output
“Fn” in “ot” off condition will remain switched on.
The parameter
“F.FE
” instead decides whether the fans must
always be switched on independently of the defrosting status
(“F.FE”=on) or switched off during defrosting (“F.FE”=oF).
In this latter case, it is possible to delay the start up of the fans
even after the end of the defrosting of the time set in the parameter
“F.Fd”.
When this delay is active the led FAN flashing to signal the delay in
progress.
When the evaporator probe is used the fans, as well as being
conditioned by the parameters “F.tn”, “F.tF and “F.FE”, are also
conditioned by a temperature control.
It is possible to set the disablement of the fans when the
temperature measured by the evaporator probe is higher than the
one set in the parameter
“F.FL”
(temperature too hot) or when it is
ASCON TECNOLOGIC - Z31Y
- OPERATING INSTRUCTIONS - Vr. 02 - 04/12 - ISTR-MZ31YENG02 - PAG. 7
