Digital controller for variable speed compressors
XRi77CX
1. GENERAL WARNING............................................................................................................................. 1
2. GENERAL DESCRIPTION..................................................................................................................... 1
3. CONTROLLING LOADS......................................................................................................................... 1
4. VARIABLE SPEED COMPRESSOR CONTROL ............................................................................... 1
5. PULL DOWN ............................................................................................................................................ 2
6. DUAL MAP FEATURE .........................................................ERROR! BOOKMARK NOT DEFINED.
7. FRONT PANEL COMMANDS ............................................................................................................... 2
8. MAX & MIN TEMPERATURE MEMORIZATION ................................................................................ 2
9. MAIN FUNCTIONS.................................................................................................................................. 2
10. PARAMETERS ........................................................................................................................................ 3
11. DIGITAL INPUTS ..................................................................................................................................... 4
12. RS485 SERIAL LINE – FOR MONITORING SYSTEMS .................................................................. 5
13. INSTALLATION AND MOUNTING ....................................................................................................... 5
14. ELECTRICAL CONNECTIONS ............................................................................................................. 5
15. HOW TO USE THE HOT KEY............................................................................................................... 5
16. ALARM SIGNALS .................................................................................................................................... 5
17. TECHNICAL DATA.................................................................................................................................. 5
18. WIRINGS .................................................................................................................................................. 5
19. DEFAULT SETTING VALUES............................................................................................................... 5
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 XRi77CX, format 32x74mm, is microprocessor based controller, suitable for applications on
medium or low temperature ventilated refrigerating units. It has four relay outputs to control
compressor, fan, defrost, which can be either electrical or reverse cycle (hot gas) and light
(configurable). It could be provided with a Real Time Clock which allows programming of up to six
daily defrost cycles, divided into holidays and workdays. A “Day and Night” function with two different
set points is fitted for energy saving. It is also provided with up to four NTC probe inputs. The first
probe is used for temperature control. The second probe is used to control the defrost termination
temperature at the evaporator. One of the two digital inputs can operate as third temperature probe.
The fourth probe is used to control the condenser temperature (for condenser alarm management) or
to display a temperature.
The RS485 serial output allows connecting the unit to a network line (ModBUS-RTU compatible)
such as any dIXEL monitoring units of X-WEB family. The HOT-KEY receptacle allows
programming the controller by using an HOTKEY programming device.
The instrument is fully configurable through special parameters that can be easily programmed
through the frontal keyboard.
3. CONTROLLING LOADS
3.1 COMPRESSOR
The regulation is performed according
to the temperature measured by the
thermostat probe with a positive
differential (HY) over the set point: if the
temperature increases and reaches set
point plus differential, the compressor
will start. It will turn off as soon as 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 DEFROST
Two defrost modes are available through the tdF parameter: defrost through electrical heater
(tdF=EL) and hot gas defrost (tdF=in).
The defrost interval depends on the presence of the RTC (optional). The internal RTC is controlled
by means of the EdF parameter:
- EdF=in: the defrost is made every idF time – standard way for controller without RTC.
- EdF=rtC: the defrost is real time controlled, depending on the hours set in the parameters
Ld1...Ld6 (for workdays).
Other parameters are used to control defrosting cycles: the maximum length (MdF) and defrosting
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.
3.3 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.
3.3.1 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.
3.3.2 CYCLIC 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.
3.4 RELAY CONFIGURATION (PAR. oA0, oA1, oA2, oA3)
The functioning of the configurable relays (terminals 1-2 and 1-7-8) can be set by the oA1 and oA2
parameters, according to the kind of application. In the following paragraph the possible setting:
3.4.1 LIGHT RELAY
With oAx=LiG the related relay operates as light output.
3.4.2 AUXILIARY RELAY
Relay activation by digital input 1 or digital input 2 (oAx=AUS, i1F or i2F=AUS): with oAx=AUS
and i1F, i2F=AUS the AUX relay is switched on and off by digital inputs.
3.4.3 ON/OFF RELAY (OAX = ONF)
When oAx=onF, the related relay is activated when the controller is turned on and de-activated
when the controller is turned off.
3.4.4 NEUTRAL ZONE REGULATION
With oAx=db the related relay can control a heater element to perform a neutral zone action.
oAx cut in = SET-HY
oAx cut out = SET
3.4.5 ALARM RELAY
With oAx=Alr the related relay operates as alarm relay. It is activated every time an alarm happens.
Its status depends on the tbA parameter: if tbA=Y, the relay is silenced by pressing any key.
If tbA=n, the alarm relay stay on until the alarm condition recovers.
3.4.6 SECOND COMPRESSOR
If oAx=CP2, it will work as second compressor output. The anti-short cycle parameter AC1 gives the
possibility to desynchronize the compressor activations.
3.4.7 SECOND DEFROST OUTPUT
If oAx=dF2, it will work as second defrost output.
NOTE: It is also possible to manage 2 different and independent defrost by using special parameter
map. Please refer to Dixell to activate this function.
3.4.8 NIGHT BLIND MANAGEMENT DURING ENERGY SAVING CYCLES
With oAx=HES, the related relay operates to manage the night blind: the relay is energised when the
energy saving cycle is activated by digital input or frontal button.
3.4.9 HEATER FOR WATER DRIPPING
If oAx=Het, the related output will work as heater for water dripping during and after any defrost.
3.4.10 REGULATION OUTPUT
If oAx=inV, the related output will work as regulation output and will stay active as soon as the
regulation request is running.
4. VARIABLE SPEED COMPRESSOR CONTROL
The controller is able to drive variable speed compressor with frequency control input. The HOTKEY
port is able to issue a frequency signal from 30 to 200Hz, duty cycle=50%. A special cable (CABKXV1) is used to connect the frequency output of the controller to the frequency input of the
compressor. One of the available relays can be set as oAx=inV in order to control the condenser
fan. In this case the fans will be activated only when the regulation is running.
NOTE: in case of using an inverter compressor, it must be controlled ONLY from the frequency
output. DO NOT USE ANY RELAY TO CONTROL THE COMPRESSOR POWER SUPPLY.
4.1 CABLE FOR FREQUENCY OUTPUT
CAB/KXV1
4.2 PARAMETERS
The following parameters are used to set the regulation:
HY1 Differential for proportional band: (0.1 to 25.5°C; 1 to 45°F)
PMi Lower speed limit (in percentage): (0 to PMA)
PMA Upper speed limit (in percentage): (Pmi to 100%)
The wiring polarity follows:
WHITE GND (-)
GREEN FREQ (+)
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voS Speed variation when
temperature increases:
(0 to 100 Hz/min)
t1n Interval of time with speed fixed to P
m
i after start
-
up: (0 to 999 min)
Flashing
Fans delay after defrost in progress.
vo2 Speed variation when temperature decreases: (0 to 100 Hz/min)
t1F Interval of time with speed fixed to Pmi before stopping regulation: (0 to 999 min)
tC2 Interval of time to control temperature deadlocks: (1 to 255 min)
SPi Speed in case of probe error: (Pmi to PMA)
The value of the par HY1 can normally be set to the same value of par. HY. In this way, the
regulation band will be extended from SET to SET+HY+HY1. The device will activate the regulation
when the measured temperature will go over the SET+HY value and will stop the regulation when the
temperature will reach the SET value. When the regulation is running, the frequency output, and then
the compressor speed, will be calculated in proportional way by using the Pmi…PMA band. After
reaching the SET+HY value, the controller will start increasing the frequency output, and then the
equivalent compressor speed, by using the par. voS. The speed increasing will be stopped as soon
as the proportional calculated value (for the compressor speed) hooks the requested value. In case
of temperature decrement and compressor speed higher than the new requested value, the controller
will decrease the compressor speed proportionally by using the vo2 value.
At start-up and after reaching the SET value, it is possible to force the compressor speed to Pmi for
two different intervals of time defined from par. t1n and t1F.
I case of regulation probe error, the compressor speed will be set to the value of par. Spi.
4.3 TEMPERATURE DEADLOCK CONTROL
The controller is able to detect temperature deadlocks. If the actual speed is not able to reach the
SETPOINT, and if this condition lasts more than the tC2 interval of time, then the controller will
increment the actual speed of a fixed value of 10%. The new compressor speed will stay unchanged
till reaching the SETPOINT or until another interval of time equal to tC2 will expire.
4.4 HOT GAS DEFROST
In case of using hot-gas defrost, it will be possible to set the compressor speed by using par. Aod.
5. PULL DOWN
An automatic function named PULL DOWN is implemented. This function forces the controller to
work at PMA until reaching a specific SETPOINT (par. CCS) for a maximum interval of time (par.
CCt). The PULL DOWN function is activated:
- At start-up if the temperature measured from the regulation probe is higher than the
SETPOINT
- After any defrost
- If the temperature measured from regulation probe go over the SET+HY+HY1+oHt value.
If one of the above conditions happens, the controller will maintain the maximum compressor speed
(PMA) until reaching the CCS setpoint. The maximum interval of time for any PULLDOWN is defined
from par. CCt. At the end of any PULL DOWN it is possible to set a couple of intervals (par. tAP) with
predefined compressor speed (par. tP1 and tP2).
6. FRONT PANEL COMMANDS
KEY COMBINATIONS:
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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 used parameter map. When in programming mode, it browses
the parameter codes or increases the displayed value.
(DOWN) To see the used parameter map. When 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 (when oAx=LiG).
+
+
+
To lock & unlock the keyboard.
To enter in programming mode.
To return to the room temperature display.
6.1 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
ON An alarm is occurring
ON A PULL DOWN is running
ON Energy saving enabled
ON Light on
ON Auxiliary relay on
ON Measurement unit
,
Flashing Programming phase
7. MAX & MIN TEMPERATURE MEMORIZATION
7.1 HOW TO: SEE THE MIN TEMPERATURE
1. Press and release the DOWN button.
2. The “Lo” message will be displayed followed by the minimum temperature recorded.
3. By pressing the DOWN button again or waiting for 5 sec the normal display will be restored.
7.2 HOW TO: SEE THE MAX TEMPERATURE
1. Press and release the UP button.
2. The “Hi” message will be displayed followed by the maximum temperature recorded.
3. By pressing the UP button again or waiting for 5 sec the normal display will be restored.
7.3 HOW TO: RESET THE MAX AND MIN TEMPERATURE RECORDED
1. Keep SET button pressed for more than 3 sec while the max or min temperature is displayed.
(“rSt” message will be displayed)
2. After confirming the operation, the “rSt” message will start blinking and then the normal
temperature will be displayed.
8. MAIN FUNCTIONS
8.1 TO SET THE CURRENT TIME AND DAY (ONLY WITH RTC)
When the instrument is switched on, it’s necessary to program the time and day.
1. Enter the Pr1 programming menu, by pushing the SET+DOWN keys for 3 sec.
2. The rtC parameter is displayed. Push the SET key to enter the real time clock menu.
3. The Hur (hour) parameter is displayed.
4. Push the SET and set current hour by the UP and DOWN keys, then push SET to
confirm the value.
5. Repeat the same operations with Min (minutes) and dAy (day) parameters.
To exit: Push both SET+UP keys or wait for 15 sec without pushing any keys.
8.2 HOW TO: SEE THE SET POINT
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 sec to display
the probe value again.
8.3 HOW TO: CHANGE THE SET POINT
1. Push the SET button for more than 2 sec to change the Set point value.
2. The value of the set point will be displayed and the °C or °F LED will start blinking.
3. To change the actual value, push the UP or DOWN buttons within 10 sec.
4. To memorise the new set point value, push the SET button again or wait for 10 sec.
8.4 HOW TO: START A MANUAL DEFROST
Push the DEF button for more than 2 sec and a manual defrost will start.
8.5 HOW TO: CHANGE A PARAMETER VALUE
To change a parameter value, operate as follows:
1. Enter the Programming mode by pressing the SET+DOWN buttons for 3 sec (the °C or °F LED
will start blinking).
2. Select the required parameter. Press the SET button to display its actual value.
3. Use UP or DOWN buttons to change its value.
4. Press SET button to store the new value and move to the following parameter.
To exit: press SET+UP buttons or wait for 15 sec without pressing any key.
NOTE: the set value is stored even when the procedure exits by waiting for the time-out to expire.
8.6 THE HIDDEN MENU
The hidden menu includes all the parameters of the instrument.
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