Dixell XR20CX Digital Thermostat Controller User Manual

1. Introduction

The Dixell XR20CX is a digital thermostat controller specifically designed for refrigeration applications operating at normal temperatures. This device provides a relay output to manage the compressor, ensuring precise temperature control. It is equipped with two NTC or PTC probe inputs: one for primary temperature control and an optional second input for connecting to HOT KEY terminals, which can signal a condenser temperature alarm or display an additional temperature. A digital input allows for a third temperature probe. The HOT KEY output facilitates connection to a ModBUS-RTU compatible network line, such as Dixell monitoring units of the X-WEB family, and enables programming via the HOT KEY programming keyboard. The instrument is fully configurable through easily programmable parameters.

2. Product Overview

This image displays the Dixell XR20CX digital thermostat controller. It features a grey casing with a prominent red LED display showing '-18.5 °C'. To the left of the display are three buttons: a light bulb icon (for light control), a snowflake icon (for manual defrost), and a 'SET' button (for parameter configuration). To the right are up and down arrow buttons (for navigation and value adjustment) and a power button. The 'dixell' logo is visible at the bottom right of the display.

The XR20CX controller features a compact design with a frontal dimension of 32 x 74 mm and a depth of 60 mm. It is designed for panel mounting in a 71x29mm cut-out. The display is a 3-digit red LED, 14.2 mm high, providing clear temperature readings. Connections are made via screw terminal blocks for secure wiring.

3. Technical Specifications

4. Installation and Setup

4.1 Mounting

The XR20CX is designed for panel mounting. Create a cut-out of 71x29mm in the panel where the controller is to be installed. Insert the controller into the cut-out and secure it using the provided mounting clips.

4.2 Electrical Connections

All electrical connections should be made to the screw terminal block. Ensure that the supply voltage matches the controller's specifications (230Vac ±10%, 50/60Hz for this model). Connect the compressor, probes (NTC or PTC), and any optional digital inputs as per the wiring diagram provided in the full product documentation. It is crucial to separate wires for probes, loads, and power supply to avoid interference.

• Power Supply: Connect the main power supply to the designated terminals.
• Compressor Output: Connect the compressor load to the SPST relay output terminals.
• Probe Inputs: Connect the temperature control probe to the primary NTC/PTC input. If applicable, connect the second probe for condenser temperature alarm or display to the HOT KEY terminals.
• Digital Input: Connect any free voltage contact for digital input functionality.

5. Operation

5.1 Compressor Control

The regulation of the compressor is based on the temperature measured by the thermostat probe. The compressor starts when the temperature increases and reaches the set point plus a defined differential. It then turns off when the temperature returns to the set point value. In the event of a fault with the thermostat probe, the compressor's start and stop times are managed by parameters COn (compressor ON time) and COF (compressor OFF time).

5.2 Defrost Function

Defrosting is performed by a simple stop of the compressor. The interval between defrost cycles is controlled by parameter IdF (Interval defrost). The duration of the defrost cycle is controlled by parameter MdF (Maximum defrost duration).

5.3 Parameter Programming (SET Button)

The instrument is fully configurable through special parameters. To access and program these parameters, refer to the detailed programming guide in the complete Dixell XR20CX manual. Typically, pressing the 'SET' button allows entry into the parameter menu, and the up/down arrows are used to navigate and adjust values.

6. Safety Precautions

• Voltage Verification: Always check that the supply voltage is correct and matches the instrument's requirements before connecting.
• Environmental Conditions: Do not expose the controller to water or excessive moisture. Use the controller only within its specified operating limits, avoiding sudden temperature changes that could lead to condensation.
• Power Disconnection: Always disconnect all electrical connections before performing any maintenance or service on the unit.
• Probe Placement: Ensure that the temperature probe is installed in a location not accessible by the end-user to prevent tampering or damage.
• Do Not Open: The instrument casing must not be opened by unauthorized personnel. Internal components are not user-serviceable.
• Current Limits: Always consider the maximum current that can be applied to each relay, as specified in the Technical Data section.
• Wiring Separation: Ensure that the wires for probes, loads, and the power supply are kept separate and sufficiently far from each other. Avoid crossing or intertwining these wires to prevent electrical interference or hazards.

7. Maintenance

The Dixell XR20CX controller is designed for reliable operation with minimal maintenance. Regular cleaning of the frontal panel with a soft, damp cloth is recommended. Ensure that the ventilation slots (if any) are not obstructed. Do not use abrasive cleaners or solvents.

Periodically inspect all wiring connections to ensure they remain secure and free from corrosion. Any maintenance requiring access to internal components should only be performed by qualified service personnel after disconnecting power.

8. Troubleshooting

If the instrument experiences a failure or faulty operation, first review the connections and power supply to ensure they are correct. If the issue persists, it is recommended to send the instrument back to the distributor or directly to Dixell S.r.l. Provide a detailed description of the fault to assist with diagnosis and repair. Do not attempt to repair the unit yourself if you are not qualified, as this may void the warranty and pose safety risks.

Common Indications:

• "P1" or "P2" Error: Indicates a probe error (P1 for thermostat probe, P2 for auxiliary probe). Check probe connections and the probe itself.
• "HA" or "LA" Alarm: High or Low temperature alarm. Check set points and actual temperature.
• Display Blank: Check power supply and connections.

9. Warranty and Support

For information regarding product warranty, technical support, or service, please contact your authorized Dixell distributor or refer to the official Dixell website. Ensure you have your product model number (XR20CX) and purchase details available when seeking support.