Code Description Def Min Max UOM User
User
terminal
dP1 Maximum defrost duration 45 1 240 min S YES
dP2 Max secondary evap. defrost duration 45 1 240 min S NO
d7
Skip defrost
0/1 = disabled/enabled
0 0 1 - S NO
dn Nominal skip defrost duration 75 0 100 % S NO
Thresholds dn1 (evaporator 1) and dn2 (evaporator 2) are defined by:
The algorithm keeps a counter of the defrosts to be skipped:
l if the defrost ends in a time less than dn1, the counter of the defrosts to be skipped is increased by 1;
l if the defrost ends normally, the next defrost is performed;
l when the counter reaches 3, three defrosts are skipped and then the counter is reset to 1;
l on power-up, the defrost is performed 7 times without increasing the counter, from the eighth on the
counter is updated.
Note: in power defrost mode, the maximum defrost durations dP1 and dP2 are increased by the
value of parameter ddP.
Power defrost (par. ddt, ddP)
Power defrost is used to increase the end defrost threshold dt1 (dt2 for the second evaporator) and/or
the maximum defrost duration dP1 (dP2 for the second evaporator). These increases allow more effective
defrosts. Power defrosts are performed on each defrost call during night status or when suitably
configured by the RTC parameters (sub-parameter P of parameters td1 to td8), so as to allow the user to
choose the conditions that are most suitable for this special procedure. Power defrost is activated when at
least one of the increases, ddt or ddP, has any value other than zero.
Code Description Def Min Max UOM User
User
terminal
ddt
Additional end defrost temperature delta in power defrost
mode
0 -20 20 °C/°F S NO
ddP
Additional maximum defrost time delta in power defrost
mode
0 0 60 min S NO
td1..8-
P
Defrost 1 to 8 - enable power defrost:
0/1 = normal/power defrost
0 0 1 - S NO
5.4 Evaporator
fans
The evaporator fans can be managed, if required, according to the temperature measured by any two of
the probes connected to the MPXone controller. The deactivation threshold is equal to the value of
parameter F1, and the hysteresis is equal to the value of Frd.
Note: during the dripping waiting time (in the event of network defrosts), and during the dripping
time, the evaporator fans are always off, while during the post-dripping time, if set, evaporator fan
operation depends on the setting of par. Fpd.
Fixed-speed fans
The parameters used to manage fixed-speed fans are shown below (see the connection diagram).
MPXone manages the evaporator fans as follows:
l F0 = 0 always on;
l F0 = 1 off when the difference between the two probe values Sa and Sb (defined by parameters FSa
and FSb) exceeds the threshold set for parameter F1;
l F0 = 2 on/off based on Sa probe, defined by parameter FSa.
68|5. Functions
MPXone +0300086EN rel. 1.0– 04.09.2018
To Next Page
Loading...
Need help?
General
