Emerson Dixell XR44CX Installing And Operating Instructions

Digital controller with defrost and fan management
XR44CX
1. GENERAL WARNING ........................................................................................................... 1
2. GENERAL DESCRIPTION .................................................................................................... 1
3. CONTROLLING LOADS ....................................................................................................... 1
4. FRONT PANEL COMMANDS ............................................................................................... 1
5. MAX & MIN TEMPERATURE MEMORIZATION .................................................................... 1
6. MAIN FUNCTIONS ............................................................................................................... 2
7. PARAMETERS ..................................................................................................................... 2
8. DIGITAL INPUTS .................................................................................................................. 3
9. TTL SERIAL LINE – FOR MONITORING SYSTEMS ............................................................. 3
10. INSTALLATION AND MOUNTING ......................................................................................... 3
11. ELECTRICAL CONNECTIONS.............................................................................................. 3
12. USE THE HOT KEY.............................................................................................................. 3
13. ALARM SIGNALS ................................................................................................................. 3
14. TECHNICAL DATA ............................................................................................................... 4
15. CONNECTIONS ................................................................................................................... 4
16. DEFAULT SETTING VALUES ............................................................................................... 4
1. GENERAL WARNING
1.1 PLEASE READ BEFORE USING THIS MANUAL
 This manual is part of the product and should be kept near the instrument for easy and quick
reference.
The instrument shall not be used for purposes different from those described hereunder. It

cannot be used as a safety device.
 Check the application limits before proceeding.
Dixell Srl reserves the right to change the composition of its products, even without notice,

ensuring the same and unchanged functionality.
1.2 SAFETY PRECAUTIONS
 Check the supply voltage is correct before connecting the instrument.
Do not expose to water or moisture: use the controller only within the operating limits avoiding

sudden temperature changes with high atmospheric humidity to prevent
condensation
 Warning: disconnect all electrical connections before any kind of maintenance.
Fit the probe where it is not accessible by the End User. The instrument must not be opened.

 In case of failure or faulty operation send the instrument back to the distributor or to "Dixell S.r.l."
(see address) with a detailed description of the fault.
Consider the maximum current which can be applied to each relay (see Technical Data).

 Ensure that the wires for probes, loads and the power supply are separated and far enough
from each other, without crossing or intertwining.
 In case of applications in industrial environments, the use of mains filters (our mod. FT1) in
parallel with inductive loads could be useful.
2. GENERAL DESCRIPTION
Model XR44CX, format 32 x 74 mm, is microprocessor based controller, suitable for applications on
low temperature refrigerating units. It has four relay outputs to control compressor 1 and 2, defrost 1
and 2, which can be either electrical or reverse cycle (hot gas). It is also provided with up to three
NTC or PTC probe inputs, the first one for temperature control, the second and third one, to be
located onto the evaporator, to control the defrost termination temperature on the evaporator 1 and 2.
It allows to program the controller by means the HOT KEY programming keyboard.
3. CONTROLLING LOADS
3.1 COMPRESSOR
The regulation is performed according to
the temperature measured by the
thermostat probe with a positive
differential from the set point: if the
temperature increases and reaches set
point plus differential the compressor is
started and then turned off when the
temperature reaches the set point value
again.
In case of fault in the thermostat probe the start and stop of the compressor are timed through
parameters Con and CoF.
3.2 SECOND COMPRESSOR MANAGEMENT
The relay of the second compressor is activated in parallel with the relay of the first compressor, with
a possible delay set in the AC1 parameter. Both the compressors are switched off at the same time.
3.3 DEFROST
Two defrost modes are available through the tdF parameter: defrost through electrical heater
(tdF=EL) and hot gas defrost (tdF=in).
Other parameters are used to control the interval between defrost cycles (idF), its maximum length
(MdF) and two defrost modes: timed or controlled by the evaporator's probe (P2P).
At the end of defrost dripping time is started, its length is set in the Fdt parameter. With Fdt=0 the
dripping time is disabled.
3.4 CONTROL OF EVAPORATOR FANS
The fan control mode is selected by means of the FnC parameter:
FnC=C_n, fans will switch ON and OFF with the compressor and not run during defrost.
FnC=o_n, fans will run even if the compressor is off, and not run during defrost.
After defrost, there is a timed fan delay allowing for drip time, set by means of the Fnd parameter.
1598024001 XR44CX ISA GB r2.0 21.06.2012.doc
formation of
Temper.
SET
Compr.
ON
FnC=C_Y, fans will switch ON and OFF with the compressor and run during defrost.
FnC=o_Y, fans will run continuously also during defrost.
An additional parameter FSt provides the setting of temperature, detected by the evaporator probe,
above which the fans are always OFF. This is used to make sure circulation of air only if his
temperature is lower than set in FSt.
3.4.1 Forced activation of fans
This function managed by the FCt parameter is designed to avoid short cycles of fans, that could
happen when the controller is switched on or after a defrost, when the room air warms the evaporator.
How it works: if the temperature difference between evaporator probe and room probe is higher than
the FCt parameter value, fans will be switched on. With FCt=0 the function is disabled.
3.4.2 Cyclical activation of the fans with compressor off.
When FnC=C-n or C-Y (fans working in parallel with the compressor), by means of the Fon and FoF
parameters the fans can carry out on and off cycles even if the compressor is switched off. When the
compressor is stopped the fans go on working for the Fon time. With Fon=0 the fans remain always
off, also when the compressor is off.
4. FRONT PANEL COMMANDS
To display target set point; in programming mode it selects a parameter or confirm
an operation.
(DEF) To start a manual defrost.
(UP) To see the max stored temperature; in programming mode it browses the
parameter codes or increases the displayed value.
(DOWN) To see the min stored temperature; in programming mode it browses the
parameter codes or decreases the displayed value.
To switch the instrument on and off (when onF=oFF).
To switch on and off the light output (if present).
KEY COMBINATIONS:
+
+
+
4.1 USE OF LEDS
Each LED function is described in the following table.
LED MODE FUNCTION
ON Compressor enabled
Flashing Anti-short cycle delay enabled
ON Defrost enabled
Flashing Drip time in progress
ON
An alarm is occurring
ON
Continuous cycle is running
ON Measurement unit
Time
°C/°F
Flashing Programming phase
5. MAX & MIN TEMPERATURE MEMORIZATION
5.1 HOW TO: SEE THE MIN TEMPERATURE
1.
Press and release the DOWN key.
2.
The "Lo" message will be displayed followed by the minimum temperature recorded.
3.
By pressing the DOWN key again or by waiting 5 sec the normal display will be restored.
5.2 HOW TO: SEE THE MAX TEMPERATURE
1.
Press and release the UP key.
2.
The "Hi" message will be displayed followed by the maximum temperature recorded.
3.
By pressing the UP key again or by waiting 5 sec the normal display will be restored.
5.3 HOW TO: RESET THE MAX AND MIN TEMPERATURE RECORDED
1. Keep the SET key pressed more than 3 sec, while the max or min temperature is displayed.
("rSt" message will be displayed)
2. To confirm the operation the "rSt" message will start blinking and the normal temperature will be
displayed.
XR44CX
To lock & unlock the keyboard.
To enter in programming mode.
To return to the room temperature display.
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