1592007261 XR70C-D XR72C GB r1.0 18.11.2015 XR70C – XR70D - XR72C 1/4
Digital controller with defrost and fans management
XR70C– XR70D – XR72C
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
Models XR70C and XR72C, 32x74 mm format, and XR70D, DIN rail format, are a
microprocessor based controllers, suitable for applications on medium or low temperature
ventilated refrigerating units. They have three relay outputs to control compressor, fan, and
defrost, which can be either electrical or reverse cycle (hot gas). XR70C and XR70D have a
fourth relay for alarms signalling. XR72C has a fourth relay to pilot a second compressor.
They are also provided with two NTC or PTC probe inputs, one for temperature control, the
other, to be located onto the evaporator, to control the defrost termination temperature and to
managed the fan. 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.
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.
4. FRONT PANEL COMMANDS
XR70C – XR72C XR70D
SET: To display target set point; in programming mode it selects a parameter or confirm an
operation.
(DEF) To start a manual defrost
o
(UP): To see the last temperature alarm happened; in programming mode it browses the
parameter codes or increases the displayed value.
n (DOWN) To see the last temperature alarm happened; in programming mode it browses
the parameter codes or decreases the displayed value.
KEY COMBINATIONS:
o + n
To lock & unlock the keyboard.
SET + n To enter in programming mode.
SET + o To return to the room temperature display.
4.1 USE OF LEDS
Each LED function is described in the following table.
-Programming Phase (flashing with )
- Anti-short cycle delay enabled
- Programming Phase (flashing with )
- Drip time in progress
Fans delay after defrost in progress.
An temperature alarm happened
5. TEMPERATURE ALARM AND ITS DURATION RECORDING (HACCP)
Instruments signal and
record temperature
alarms, together with
their duration and max
value reached. See
drawing:
Ex. High temperature alarm
Set
ALu
High temp. alarm
Time
Temperature
ALL
Low temp. alarm
X
X
X
Alarm duration
Max
Temperature
Safe food zone
5.1 HOW TO SEE THE ALARM DURATION AND MAX (MIN) TEMPERATURE
If the alarm LED is on, an alarm has taken place. To see the kind of alarm, the max (min)
reached temperature and alarm duration do as follows:
1. Push the Up or Down key.
2. On the display the following message is shown::
“HAL” for high temperature alarm (“LAL” for the minimum allarm), followed by the
Maximum (minimum) temperature.
Then the “tiM” (tiMe) message is displayed, followed by the “Duration” in h.mm.
3. Then the instrument displays the temperature once again.
NOTE1: if an alarm is still occurring the “tim” shows the partial duration.
NOTE2: the alarm is recorded when the temperature come back to normal values
5.2 HOW TO RESET A RECORDED ALARM OR ONE THAT IS STILL
OCCURRING
1. Hold the SET key pressed for more than 3s, while the recorded alarm is displayed. (the
rSt message will be displayed)
2. To confirm the operation, the “rSt” message starts blinking and the normal temperature
will be displayed.
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