57
ENG
mpxone +0300086EN rel. 2.2 - 13.11.2023
Functions
Defrost delay (parameter d5)
Parameter d5 represents the delay between enabling or calling a defrost, and the actual start. Also active when d4=0.
Code Description Def Min Max UOM User User terminal
d5 Defrost delay at power-on or (for secondary) after control from main
0 = delay disabled
0 0 240 min S NO
For main/secondary networks where the defrost needs to be activated from a digital input on the main, parameter d5 can be
used to delay the various defrosts, thus avoiding current overloads.
Dripping time after defrost (par. dd)
This parameter defines the time that the compressor and the evaporator fans stop following a defrost so as to allow the evapo-
rator to drip. If dd=0 no dripping time is enabled, and at the end of the defrost control resumes immediately, without stopping
the compressor and the fan, if active.
Code Description Def Min Max UOM User User terminal
dd Dripping time after defrost (fans off) 0 = no dripping 2 0 15 min S NO
Valve positioning during defrost (par. dSb)
A fixed position (as a percentage) can be set for valve opening throughout the defrost procedure, from the end of pump-down
to the start of the dripping phase. The valve will behave as defined by parameters cP1 and Pdd starting from the post-dripping
phase. The opening percentage is applied in all the types of defrost. The function is activated by setting parameter dSb to a value
between 1 and 100; this value indicates the position of the valve as a % of the number of steps (not capacity).
Setting the parameter to 1, the valve is closed completely during defrosts. Setting the parameter to 0, positioning is disabled and
the valve will behave as defined for the type of defrost selected.
Code Description Def Min Max UOM User User terminal
dSb Valve position during defrosts 0: according to the set type of defrost 1:
forced closed 2-100: percentage opening
0 0 100 % M NO
Pump down duration (par. dH1)
The pump down phase is the period in which the evaporator is emptied of liquid refrigerant. Parameter dH1 defines the duration
of the pump down phase during all types of defrost.
Code Description Def Min Max UOM User User terminal
dH1 Pump down duration
0 = pump down disabled
0 0 999 s M NO
Caution:
the controller does not have two separate outputs to manage the compressor and solenoid valve.
Running time defrost (par. d10, d11)
Running time is a function that determines when the refrigeration unit needs defrosting. In particular, it is assumed that if the
evaporator temperature measured by probe Sd remains continuously below a certain set threshold (d11) for a certain time (d10),
the evaporator may be frozen and a defrost is activated. The time is reset if the temperature returns above the threshold.
Code Description Def Min Max UOM User User terminal
dt1 End defrost temperature (read by Sd) 8 -50 50 °C/°F S YES
dt2 End defrost temperature (read by Sd2) 8 -50 50 °C/°F S NO
d10 Defrost time in running time mode
0 = function disabled
0 0 240 min S NO
d11 Defrost temperature threshold in running time mode -30 -50 50 °C/°F S NO
300086_067_R01
d10
t
t
ON
Sd
DEF
OFF
dt1
d11
Ref. Description
Sd Defrost probe
DEF Defrost
t time
Fig. 5.u
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