Carel plug-in User Manual page 25

plug-in
d4: defrost at instrument on
Activates a defrost cycle when the instrument is turned on. The request for defrost when the unit is turned on has priority over the
activation of the compressor and the activation of the continuous cycle.
The possible values are:
0 = no, no defrost is performed when the instrument is turned on;
1 = yes, a defrost cycle is performed when the instrument is turned on.
Forcing a defrost cycle when the instrument is turned on may be useful in special situations, e.g. if the system is subject to frequent
voltage drops. In fact, in the event of power failures the instrument's internal clock, which calculates the interval between two
defrosts, starting from zero, is reset. If the frequency of the voltage drop were, in an extreme case, greater than the defrost
frequency (e.g. a voltage drop every 8 hours against a defrost every 10 hours), the control would never perform a defrost. In this
type of situation it is better to activate the defrost when the unit is turned on, above all if the defrost is controlled by temperature
(probe on the evaporator), so unnecessary defrosts are avoided or at least reduced in time. In the case of systems with many units,
if defrost on start-up is selected, after a voltage drop all the units will start a defrost. This may cause overloads. To avoid this,
parameter d5 can be exploited, which allows a delay to be set before the defrost starts, a delay which obviously must be different
for each unit.
Def.: d4=0, the instrument does not perform a defrost when the unit is turned on. Available on all models.
d5: defrost delay at instrument on or from multifunction input
Represents the time which must elapse between when the control is turned on and the start of the defrost.
In the case where the digital input is used to enable the defrost (see parameter A4=2) or to start a defrost from an external contact
(see parameter A4=3), this parameter represents the delay between the enabling of the defrost, or its request, and the effective start
of the cycle. The defrost from digital input (see parameter A4) can be exploited to perform defrosts in real time. Simply connect a
timer to the multifunction digital input (again see parameter A4). The defrost will be activated when the timer contact is closed. In
the case where more than unit is connected to the same timer, it is recommended to set parameter d5 to delay the defrosts to a
different time for each unit. Furthermore, to avoid unnecessary defrosts controlled by the instrument's internal clock, it is suggested
to set parameter dI=0 (only manual defrosts from the keypad or multifunction contact) or to set dI to a value which is greater than
the maximum set interval, allowing operation with safety defrosts in respect to the external timer.
Def.: d5=0 (no delay in the start of the defrost from when the instrument is turned on or from the activation of the multifunction
input)
Available on all models.
d6: display off during defrost
Blocks the display of the ambient temperature during the defrost cycle at the last value read before the current defrost.
The display normally returns when the measurement first reaches the set point or, in any case, after the set alarm bypass time after
defrost (parameter d8).
If the display during defrost is enabled, the instrument displays alternatively the message dF and the value read by the control
probe. This warns that possible high temperatures are due to defrost in progress. The off mode is also valid for the display of the
second probe (Par. /4), if enabled.
Def.: d6=1 (during defrost the last temperature measured before the start remains on the display). Available on all models.
dd: dripping time
This parameter forces the compressor and the evaporator fans off after a defrost, in order to allow the evaporator to drip.
The value of this parameter indicates the minutes of rest, if dd = 0 no dripping is set, therefore at end defrost the compressor starts
immediately.
Def.: dd=2 min. Available on all models.
d8: alarm bypass time after defrost
Indicates the time the high temperature alarm is bypassed from the end of the defrost
Def.: d8=1 bypass time. Available on all models.
Cod. +030221881 rel. 1.5 - 26/10/10 25