Carel MPXone - Page 56

56
ENG
mpxone +0300086EN rel. 2.2 - 13.11.2023
Functions
Start/end defrost synchronised by main (par. d2, d3)
The parameters determine whether, in a local network, the defrost on the main and on the secondary devices should be syn-
chronised at the start, at the end or both.
Code Description Def Min Max UOM User User terminal
d2 End defrost synchronised by main
0 = not synchronised
1 = synchronised
101- SNO
d3 Send start network defrost signal (for main)
0 = Yes, 1 = No
Ignore start network defrost signal (for secondary)
0 = No, 1 = Yes
001- SNO
d2: end defrost synchronised by main; in general, this parameter should be set to 1 on the main and secondary units in a multi-
plexed group (synchronised end defrost). When synchronised end defrost is set, control in the subnetwork only resumes when
all the units have finished the active defrost phase.
d3: disable network defrost; if set to 1 on a main unit, the defrost command will not be broadcast to the secondary units in the
same LAN; if set to 1 on a secondary unit, this will not start the defrost procedure if receiving the command from the main.
Caution
dI: maximum interval between consecutive defrosts; especially for hot gas defrosts, it is recommended to set this parameter to
0 on all units connected in a main/secondary configuration, so as to prevent non-synchronised defrosts from being carried out
in the event where communication on the LAN is interrupted.
Best practices for managing defrost in a local network of cabinets
As a general rule, in a main/secondary network:
1. A manual start of a defrost (from the user interface or APPLICA) is always performed by the controller itself and not broadcast
across the network to the other controllers.
2. Defrost is activated:
– by appropriately setting d3, on the main and secondary units; the start of a defrost programmed on the main is broadcast
to the secondary units,
– from the supervisor, sending the request to the main controller and consequently to the secondary devices,
– via digital input.
3. Defrost is deactivated:
– when the defrost measures detects a temperature higher than the end defrost temperature dt1;
– if there is no defrost probe, the defrost ends after the maximum time set by parameter dP1. (***)
(***) IMPORTANT NOTICE: for hot gas or heater defrosts, it is especially important for the maximum defrost time to set
appropriately, always remembering that the priority is preservation of the stored goods
4. In a main/secondary network with hot gas defrost:
– depending on the setting of dHG, the equalising valve can be closed or open
– there can be no local defrosts (+++)
– the hot gas valve is always local only (one for each controller)
– the liquid solenoid valve can be local or shared in the network
– the suction and equalising valves can be local or shared in the network
– the end of hot gas defrosts must be synchronised
– the change from one phase to another is always synchronised between all controllers
(+++) NOTICE: If a multiplexed hot gas defrost is set, attention must be paid to the possible consequences of local defrosts
carried out by individual units that are not synchronised with the remaining units in the multiplexed group.
End defrost by timeout signal (par. r3)
For defrosts that end by temperature (d0=0), this enables the end defrost by timeout signals Ed1 and Ed2 when the maximum
time is reached (dP1).
Code Description Def Min Max UOM User User terminal
r3 End defrost by timeout signal
0 = disabled, 1 = enabled
001- SNO
Defrost at power on (par. d4)
The defrost request at power on has priority over the control request and activation of the continuous cycle. For main controllers,
the defrost at power-on will be a network defrost; for secondary controllers it will be local.
Code Description Def Min Max UOM User User terminal
d4 Defrost at power on (main = network defrost;
secondary = local defrost) 0 = No, 1 = Yes
001- SNO