1592020080 XR72CX GB m&M r1.1 27.03.2015
XR72CX
1/4
Digital controller with defrost and fans management
XR72CX
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 formation of 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
XR72CX
, format 32 x 74 mm, is microprocessor based controller, suitable for applications on
medium or low temperature ventilated refrigerating units. It has four relay outputs to control
compressor 1, compressor 2, fan and defrost, which can be either electrical or reverse cycle (hot
gas). It is also provided with up to four NTC or PTC probe inputs, the first one for temperature
control, the second one, to be located onto the evaporator, to control the defrost termination
temperature and to managed the fan. The digital input can operate as third temperature probe. The
fourth one, to connect to the HOT KEY terminals is used to signal the condenser temperature alarm
or to display a temperature.
The HOT KEY output allows to connect the unit, by means of the external module XJ485-CX, to a
network line
ModBUS-RTU
compatible such as the Dixell monitoring units of X-WEB family. It
allows to program the controller by means the HOT KEY programming keyboard.
The instrument is fully configurable through special parameters that can be easily programmed
through the 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.
Time
Temper.
Compr.
SET
ON
In case of fault in the thermostat probe the start and stop of the compressor are timed through
parameters “
COn
” and “
COF
”.
3.2
2
ND
COMPRESSOR MANAGEMENT – XR72C ONLY
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 FSt parameter. With FSt =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.
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.
Functioning:
if the difference of temperature between the evaporator and the room
probes is more than the value of the Fct parameter, the fans are 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 in parallel to 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, 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 off, if onF = oFF.
Not used.
KEY COMBINATIONS:
+
To lock & unlock the keyboard
.
+
To enter in programming mode.
+
To return to the room temperature display.
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
Fans enabled
Flashing Fans delay after defrost in progress.
ON
An alarm is occurring
ON
Continuous cycle is running
ON
Energy saving enabled
°C/°F
ON
Measurement unit
°C/°F
Flashing Programming phase
5.
MAX & MIN TEMPERATURE MEMORIZATION
5.1
HOW TO SEE THE MIN TEMPERATURE
1.
Press and release the
n
key.
2.
The “Lo” message will be displayed followed by the minimum temperature recorded.
3.
By pressing the
n
key again or by waiting 5s the normal display will be restored.
5.2
HOW TO SEE THE MAX TEMPERATURE
1.
Press and release the
o
key.
2.
The “Hi” message will be displayed followed by the maximum temperature recorded.
3.
By pressing the
o
key again or by waiting 5s the normal display will be restored.
5.3
HOW TO RESET THE MAX AND MIN TEMPERATURE RECORDED
1.
Hold press the SET key for more than 3s, while the max. or min temperature is displayed. (rSt
message will be displayed)
2.
To confirm the operation the “rSt” message starts blinking and the normal temperature will be
displayed.
6.
MAIN FUNCTIONS
6.1
HOW TO SEE THE SETPOINT
1.
Push and immediately release the
SET
key: the display will show the
Set point value;
2.
Push and immediately release the
SET
key or wait for 5 seconds to
display the probe value again.
6.2
HOW TO CHANGE THE SETPOINT
1.
Push the
SET
key for more than 2 seconds to change the Set point value;
2.
The value of the set point will be displayed and the “
°C” or “°F”
LED starts blinking;
3.
To change the Set value push the
o
or
n
arrows within 10s.
4.
To memorise the new set point value push the
SET
key again or wait 10s.
