Emerson dixell XW20LT Installing And Operating Instructions

Digital controller for medium-low temperature
refrigeration applications
XW20LT
1. GENERAL WARNING .................................................................................................................... 1
2. GENERAL DESCRIPTION............................................................................................................. 1
3. CONTROLLING LOADS ................................................................................................................ 1
4. FRONT PANEL COMMANDS ........................................................................................................ 1
5. AUTOMATIC KEYBOARD LOCK .................................................................................................. 2
6. MAX & MIN TEMPERATURE MEMORIZATION ........................................................................... 2
7. MAIN FUNCTIONS......................................................................................................................... 2
8. PARAMETERS ............................................................................................................................... 2
9. DIGITAL INPUTS ........................................................................................................................... 4
10. TTL SERIAL LINE – FOR MONITORING SYSTEMS ................................................................... 4
11. X-REP OUTPUT – OPTIONAL ...................................................................................................... 4
12. INSTALLATION AND MOUNTING ................................................................................................ 4
13. ELECTRICAL CONNECTIONS...................................................................................................... 4
14. HOW TO USE THE HOT KEY ....................................................................................................... 4
15. ALARM SIGNALS .......................................................................................................................... 5
16. TECHNICAL DATA......................................................................................................................... 5
17. CONNECTIONS ............................................................................................................................. 5
18. 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 Srl." (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 XW20LT, format 38x185mm, is microprocessor based controller, suitable for applications on
medium or low temperature ventilated refrigerating units. It has 2 relay outputs to control compressor
and light. It could be provided with a Real Time Clock which allows programming of up to 6 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 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. One of the 2 digital inputs can operate as third
temperature probe. The fourth probe is used to signal the condenser temperature alarm or to display a
temperature.
The HOT KEY output allows connecting the unit, by means of the external module XJ485-CX, to a
network line ModBUS-RTU compatible such as the dIXEL monitoring units of X-WEB family. It
allows programming 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.
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 (when present): defrost through electrical
heater (tdF = EL) and hot gas defrost (tdF = in). If tdF is not present, the defrost is controlled with
time or temperature. If the RTC is present is controlled by means of parameter EdF:
EdF=in: a defrost starts after elapsing the idF time (standard way for controller without RTC
-
and with not visible EdF parameter).
1592027615 XW20LT RTC GB r1.0 18.09.2012
Temper.
SET
Compr.
ON
EdF=rtC: defrosts are scheduled by using a real time clock system, depending on the hours
-
set in the parameters Ld1..Ld6, during workdays, and in Sd1...Sd6 during holidays.
Other parameters are used to control defrost cycles: its maximum length (MdF) and two defrost
modes: timed or controlled by the evaporator's probe, depending on which probe is present
(parameter PxP) and enablde for defrost (dFP=PxP).
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 AUXILIARY OUTPUT CONFIGURATION
The functioning of the auxiliary relay (default terminals 1-3) can be set by the oA3 parameters
according to the kind of application. In the following paragraph the possible settings are explaided.
3.3.1 Auxiliary thermostat
A possible use is the anti condensing heater, with the possibility of switching it on and off also by
keyboard.
Parameters involved:
ACH: kind of regulation for the auxiliary relay: Ht: heating; cL: cooling;
-
SAA: set point for auxiliary relay;
-
SHy: differential for auxiliary relay;
-
ArP: probe for auxiliary relay;
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Sdd: auxiliary output off during defrost.
-
The differential is given by the SHy parameter.
The auxiliary relay can be switched on also by using the AUX button. In this case it remains on till it's
manually switched off.
NOTE: If oA3=US and ArP=nP (no probe for auxiliary output), the AUX relay can be activated only by
pushing the AUX button of the keyboard.
3.3.2 On/off relay – oA3 = onF
In this case the relay is activated when the controller is turned on and de-activated when the controller
is turned off.
3.3.3 Neutral zone regulation
With oA3=db the AUX relay can control a heater element to perform a neutral zone action.
output oAx cut in = SET-HY;
-
output oAx cut out = SET.
-
3.3.4 Second compressor
With oA3=CP2, the AUX relay operates as second compressor: it is activated in parallel with the relay
of the first compressor, with a proper activation delay (set in the AC1 parameter). Both the
compressors are switched off at the same time.
3.3.5 Alarm relay
With oA3=ALr the AUX relay operates as alarm relay. It is activated every time an alarm happens. Its
status depends on the tbA parameter:
tbA=Y: the relay is silenced by pressing any key;
-
tbA=n: the alarm relay remains on until the alarm condition recovers.
-
3.3.6 Night blind management during energy saving cycles
With oA3=HES the AUX relay operates to manage the night blind: the relay is energised when the
energy saving cycle is activated by digital input, frontal button or RTC (optional).
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.
(OFF) To switch the instrument off, if onF=oFF.
(LiG) To switch the light, if oAx=Lig.
KEY COMBINATIONS:
+

+
+
4.1 USE OF LEDS
Each LED function is described in the following table.
LED MODE FUNCTION
Time
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
ON Light on
ON Auxiliary relay on
ON Measurement unit
°C/°F
Flashing Programming phase
XW20LT
To lock & unlock the keyboard.
To enter in programming mode.
To return to the room temperature display.
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