Ascon Tecnologic - B05B - OPERATING INSTRUCTIONS - PAG. 13
In order to avoid unnecessary defrosts when the evaporator
temperature is high, the parameter
tS
allows to establish the
temperature referred to the evaporator probe below which
defrosts are possible.
In this way, if the temperature measured by
eP
probe is
higher than the temperature set at parameters
tS
and
tE
the defrosts are inhibited.
tE
ts
Defrost
dF
off
off
off
ON
ON
A
B
Temp.
time
C
(NO defrost)
dE
di/Sd
(Defrost)
di
di
di
(Defrost)
EP
Defrost end examples:
Defrost
A
ends due to the reaching
of
tE
temperature, defrost
B
ends at the end of
dE
time as
the temperature
tE
has not be reached, defrost
C
does not
take place as the temperature is higher than
tS
.
tE
ts
off
off
off
off
di/Sd
ON
ON
ON
time
di
(Defrost)
dE
1°
Temp.
Defrost
dF
EP
Example of electric defrost with thermostat:
Electric de-
frost with evaporator temperature control: defrost ends after
dE
programmed time. During defrost, the
dF
output switches
ON/OFF
in order to control evaporator temperature in heat-
ing mode with set point
tE
and 1° differential (Hysteresis).
The defrost cycle in progress is signaled by the lighting up of
the LED
.
At the end of defrost, it is possible to delay the new compres-
sor start up (
ot
output) at the time set with parameter
td
to
allow the evaporator to drain.
During this delay, the LED flashes to indicate the draining
in progress.
5.8.4
Defrosts in event of evaporator probe error
In event of
EP
evaporator probe error the defrosts occur at
intervals
Ei
and duration
EE
.
In case a probe error occurs when the time remaining to the
start or the end of defrost is lower than those normally set at
parameters related to error conditions probe, the start or the
end of the defrost takes place with the shortest time.
Those functions are provided when the evaporator probe is
used because the defrost duration is normally set longer than
necessary as it works as a safety feature (the temperature
value measured by the probe causes the defrost to end earli-
er) 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 Defrosting
Through parameters
dL
and
dA
it is possible to define the
display behaviour during defrost.
dL
=
on
The
dL
parameter locks the display during all the
defrost cycle at the last
Pr1
probe temperature read-
ing until, at the end of defrost, the temperature has
not reached the lock value or the [
SP
+
d
] value or is
elapsed the time set at parameter
dA
.
dL
=
Lb
Shows the label
dF
during the defrost cycle and
Pd
after the defrost until, at the end of defrost, the
Pr1
temperature has not reached the last reading value
or the value [
SP
+
d
] or is elapsed the time set on
parameter
dA
.
dL
=
oF
During the defrost cycle the display keeps showing the
temperature measured by the
Pr1
probe.
5.9
Evaporator fans control
All the parameters relative to the fans control are contained
in the
-fn
group.
The
Fn
output evaporator fans control depends on certain
control statuses of the instrument and the temperature
measured by the
EP
evaporator probe.
In the case the
EP
evaporator probe is not used or in error ,
the
Fn
output is activated only depending on the parameters
tn
,
tF
and
FE
.
Through parameters
tn
and
tF
is possible to force the fans
functioning when the
ot
compressor output is OFF.
When
ot
output is OFF, is possible to set the instrument so
that the
Fn
output continues working in cycles according to
the times programmed at the parameter
tn
(fan activation
time when compressor is OFF) and
tF
(fan deactivation time
when compressor is OFF).
When
ot
output is switched OFF the instrument activates the
Fn
output for the time
tn
, then deactivates it for the time
tF
and so on whilst the
ot
output remains OFF.
Setting
tn
=
oF
, the
Fn
output will be disabled when the
ot
output is deactivated (evaporator fans off with compressor
OFF or fans connected to compressor operations).
Programming
tn
to any value and
tF
=
oF
the
Fn
output
remains switched ON also when
ot
output is OFF.
Parameter
FE
allows to determine whether the fans must be
switched ON independently of the defrost status (
FE
=
on
) or
switched OFF during defrosting (
FE
=
oF
).
In this latter case it is possible to delay the fans restarting
even after the end of the defrost by the time set with parame-
ter
Fd
. When this delay is active the LED
flashes to point
out the delay in progress.
When the
EP
evaporator probe is used the fans, as well as
being conditioned by the parameters
tn
,
tf
and
FE
, are also
conditioned by a temperature control.
In fact, it is possible to set the fans disabling when the tem-
perature measured by the evaporator probe (
EP
) is higher
than the one set at parameter
FL
(temperature too hot) or
even when it is lower than the one set at parameter
LF
(tem-
perature too cold). Associated with these parameters there is
also the relative differential that can be set with parameter
DF
.
Note:
Particular attention should be paid to the proper use
of the fan control functions according to the tempera-
ture because in a typical refrigeration application the
