Carel MPXone - Page 53

53
ENG
mpxone +0300086EN rel. 2.2 - 13.11.2023
Functions
5.3.1 Heater defrost (d0 = 0, 2, 4): duty cycle
The duty cycle refers to the default values of parameters F2 and F3. The electronic valve can be opened to the initial value set
for cP1 for a period equal to Pdd.
300086_059_R01
t
Pdd
cP1
F3F2
OFF
SV/CMP
EEV
FAN
DEF
refrig refrigpump
down
drip
(dd)
post drip
(Fd)
res
ON
OFF
ON
OFF
ON
OFF
ON
Ref. Description
t Time
FAN Fan
DEF Defrost
drip Dripping
SV/CMP Solenoid/compressor
EEV Electronic expansion valve
Pdd Valve position maintenance time
after defrost
Post drip Post-dripping
Fig. 5.q
The pump down phase is the period in which the evaporator is emptied of liquid refrigerant, and can be disabled by setting
dH1=0 (see “Pump down duration”).
Operation of the fan during the pump down phase depends on parameters F2 and F3.
During the dripping phase the fan is always off, while during the post-dripping phase operation depends on the setting of
parameter Fpd.
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
dH1 Pump down duration
0 = pump down disabled
0 0 999 s M NO
F2 Evaporator fans with compressor off
0 = see F0 1 = always off
101- SYES
F3 Evaporator fans during defrost
0 = see F0, 1 = off
101- SF3
Fd Post-dripping time after defrosting
(fans off with control active)
2 0 15 min S NO
cP1 Initial valve position when control starts 30 0 100 % M NO
Pdd Initial valve position maintenance time after defrost 10 0 30 min S NO
dSb Valve position during defrost
0: as defined by the type of defrost
1: forced closed
2 to 100: opening percentage
0 0 100 % M NO
5.3.2 Hot gas defrost (d0 = 1, 3): duty cycle
MPXone can manage defrosts by installing a hot gas injection solenoid valve. This type of defrost can be controlled in two ways:
• Hot gas by temperature (d0=1);
• Hot gas by time (d0 = 3).
In the former case, the defrost ends when reaching the temperature set for parameter dt1 (end defrost threshold (read by Sd)).
In the latter case, the defrost ends after a set time (parameter dP1 = maximum defrost duration).
The duty cycle refers to the default values of parameters F2 and F3. The valve can be opened to the initial value set for cP1 for a
period equal to Pdd.
Notice: parameter dP1 is also taken into account when end defrost by temperature is selected. If the threshold dT1 is not
reached, the defrost will end after the maximum duration (dP1).
The pump down phase is the period in which the evaporator is emptied of liquid refrigerant, and can be disabled by setting
dH1=0 (see “Pump down duration”). In the hot gas phase, the hot gas injection solenoid valve (HGSV) is opened and the elec-
tronic valve (EEV) is brought to position dSb (default for closing). Operation of the fan during the pump down and hot gas
phases depends on parameters F2 and F3. During the dripping phase, the fan is always off, while during the post-dripping phase
operation depends on the setting of parameter Fpd.