Defrost - Carel MPXPRO User Manual

ENG
Shared network solenoid
If using solenoid valves, on Master controllers only the solenoid output
(relay 1 - AUX4) can be confi gured as a network solenoid output. The
function is useful for multiplexed showcases: the network solenoid valve
is only connected to the Master controller, which opens when at least
one of the Slaves is in cooling request.
Par. Description
r7 Master solenoid valve confi guration
0 = local valve;
1 = network valve (connected to Master)
If confi gured as the network solenoid, the valve is::
• open: if at least one of the controllers requires cooling;
• closed: if there is no control request or if at least one of the controllers
has a serious valve alarm (low superheat, low suction temperature,
high evaporation pressure), when suitably confi gured. See parameters
P10 and PM5 (paragraph 6.10).
EEV
SV M
EEV
Key
E Fan-forced evaporator
SV Solenoid valve
EEV Electronic expansion valve

5.6 Defrost

Introduction
Parameters td1 to td8 can be used to set up to 8 defrost events based on
the controller clock (RTC) and to activate the Power Defrost (see par. 6.7)
Par. Description
td1 to 8 Defrost 1 to 8 (press Set)
d_ Defrost 1 to 8 - day
h_ Defrost 1 to 8 - hour
n_ Defrost 1 to 8 - minute
P_ Defrost 1 to 8 - power defrost activation
MPXPRO can manage the following types of defrost, depending on the
setting of parameter d0:
1. heater, located near the evaporator;
2. hot gas;
3. multiplexed hot gas.
The defrost can end by temperature, in which case the defrost probe
Sd must be installed, or by time. In the fi rst case the defrost ends when
the defrost probe Sd exceeds the end defrost value dt1 or the time
dP1 has elapsed, in the second case when the defrost phase exceeds
the maximum time dP1. At the end of the defrost the dripping phase
may begin (if dd>0), during which the compressor and the fans are off ,
followed by the post-dripping phase (if Fd>0), during control resumes
with the fans off . See the chapter on Advanced functions.
MPXPRO - + 0300055EN rel. 1.0 30/08/10
Def Min Max
0 0 1
MASTER
MPX PRO
CAREL
!
MPXPRO
P
E T
SLAVE
CAREL MPX PRO
!
MPXPRO
T
E
Fig. 5.i
P Evaporation pressure (PEu)
T Superheated gas temperature (tGS)
C Condenser
Def Min Max
- - -
0 0 11
0 0 23
0 0 59
0 0 1
The type of display on user terminal and the remote display during the
defrost can be selected by setting parameter d6.
Par. Description
dt1 End defrost temperature (read by Sd)
dP1 Maximum defrost duration
d0 Type of defrost
0 = heater by temperature
UoM
1 = hot gas by temperature
-
2 = heater by time
3 = hot gas by time
4 = heater by time with temp. control
Tab. 5.q
5 = multiplexed hot gas by temperature
6 = multiplexed hot gas by time
d6 Display on terminals during defrost
0 = temperature alternating with 'dEF'
1 = freeze display
2 = 'dEF'
Below is the trend of the defrost output based on the setting of parameter
d0.
dt1
ON
DEF
OFF
ON
DEF
OFF
ON
DEF
OFF
Key
t Time
dt1 End defrost temperature
dP1 Maximum defrost duration
The heater defrost by time with temperature control (d0=4) activates
the defrost output only if the evaporator temperature (Sd) is less than
the value of parameter dt1, and ends after the time defi ned by dP1. This
function is useful for energy saving.
UoM
-
day
hour
min
-
Tab. 5.r
36
Def Min
8 -50.0
45
0
1
Sd
d0=0
d0=2
d0=4
dP1
Fig. 5.j
Sd Defrost probe
DEF Defrost
Max UoM
50.0 °C/°F
1 240 min
0 6 -
0 2 -
Tab. 5.s
t
t
t
t