This document describes the Danfoss EKC 202A,B,C and EKC 302A,B controllers for temperature control in refrigeration applications. These controllers are designed for use in supermarkets for temperature control in refrigeration appliances and cold rooms, managing defrost, fans, alarms, and lighting. The EKC 202 series is intended for front panel mounting, while the EKC 302 series is for DIN-rail mounting.
Function Description
The controller operates by receiving a temperature signal from one sensor, which is typically placed in the cold air flow after the evaporator or in the warm air flow just before it. Based on this signal, the controller manages the defrost cycle, which can be either natural or electric. Defrost termination can be achieved based on time or temperature, with a dedicated defrost sensor providing direct measurement of the defrost temperature.
The controller features two to four relays, depending on the specific model, to manage various functions:
- Refrigeration: Controls the compressor or solenoid valve.
- Defrost: Initiates and terminates defrost cycles.
- Fan: Manages fan operation.
- Alarm: Activates in case of abnormal conditions.
- Light: Controls lighting.
Different applications are supported by the various models:
- EKC 202A / EKC 302A: These models have two relay outputs, two temperature sensors, and a digital input. They control temperature by starting/stopping the compressor or solenoid valve and manage electrical or gas defrost. Relay two can be configured for an alarm function if needed. Defrost in these models typically involves continuous fan operation for air circulation.
- EKC 202B / EKC 302B: Equipped with three relay outputs, two temperature sensors, and a digital input, these controllers also manage temperature and defrost. Relay output three is specifically used for fan control.
- EKC 202C: This model offers four relay outputs, two temperature sensors, and a digital input. It provides temperature control, defrost management, and fan control. The fourth relay output can be used for either an alarm or a light function.
Usage Features
The controllers offer a range of integrated refrigeration-technical functions and user-friendly features:
- Display: Values are shown with three digits, configurable for °C or °F.
- LED Indicators: Light-emitting diodes on the front panel indicate active functions (refrigeration, defrost, fan). They flash during an alarm, and the error code can be viewed by pressing the top button.
- Buttons: The front panel includes upper, middle, and lower buttons for navigation and setting adjustments. The upper and lower buttons change values, while the middle button confirms selections.
- Menu Navigation: To change settings, users press the upper button for a few seconds to enter the parameter menu, then use the upper/lower buttons to find the desired parameter. Pressing the middle button displays the parameter's current value, which can then be adjusted and saved.
- Alarm Management: Alarms can be acknowledged and cleared by briefly pressing the upper button. If multiple alarm codes exist, they can be scanned using the upper or lower buttons.
- Temperature Setting: The set temperature can be adjusted by pressing the middle button until the value is shown, then using the upper/lower buttons to select a new value, and finally pressing the middle button to confirm.
- Manual Defrost: Defrost can be manually started or stopped by pressing the lower button for four seconds. The defrost sensor temperature can be viewed by briefly pressing the lower button.
- Digital Input: A versatile digital input supports various functions, including:
- Door contact with alarm for prolonged open doors.
- Defrost start.
- Start/stop of regulation.
- Night operation change-over.
- Switching between two temperature references.
- Case cleaning function.
- Inject on/off.
- Defrost on Demand: Defrost can be initiated based on aggregate refrigeration time or evaporator temperature (S5 sensor). The latter function is particularly useful in 1:1 systems to optimize defrost cycles based on ice build-up.
- Case Cleaning Function: This feature simplifies the cleaning process by allowing users to cycle through different phases (stopping refrigeration, stopping fans, restarting refrigeration) with three presses of a switch. During cleaning, no temperature monitoring occurs, and a cleaning alarm can be transmitted over the network for logging.
- Instant Programming: A programming key allows for quick and easy transfer of settings between controllers.
- Extra Module: The controller is designed to accommodate an insertion module, which can be easily pushed in if additional functionalities are required.
Maintenance Features
The controllers are built with features that enhance reliability and ease of maintenance:
- IP65 Density (EKC 202): The front panel of the EKC 202 models offers IP65 protection, ensuring resistance to dust and water ingress, which is crucial in refrigeration environments.
- 100% Tight Design: The buttons and seal are integrated into the front panel using a special molding technique, creating a seamless and tight unit that prevents moisture or dirt from entering.
- Factory Calibration: The controllers are factory-calibrated to ensure high measurement accuracy, surpassing the EN 441-13 standard, especially when using Pt 1000 ohm sensors, without requiring subsequent calibration.
- Power Failure Resilience: In case of power failure, the timer value for defrost is saved and continues from where it left off when power returns. For prolonged power failures (over four hours), a battery module can be mounted in the EKC 202 to maintain the real-time clock.
- Relay Lifetime Extension (EKC 302): The EKC 302 models offer an external relay function (c70) that allows forcing built-in relays to connect at the voltage's zero crossing, which can extend relay lifetime and increase load capacity.
- Error Reporting: The controller provides fault codes (E-alarms) and alarm codes (A-alarms) to help diagnose issues. E-alarms indicate defects in the installation or controller itself, while A-alarms indicate conditions exceeding set limits. These are displayed on the front panel and can be scanned.
- Settings Backup and Restore (EKC 202 only): The EKC 202 models allow users to save current settings to a programming key (065) and load previously saved settings from a programming key (066). This is useful for quick configuration of multiple units or restoring settings after maintenance.
- Factory Reset: The controller can be reset to factory-set values by cutting off the supply voltage, then depressing the upper and lower buttons simultaneously while reconnecting the supply voltage.
- Sensor Type Configuration: The controller supports different sensor types (Pt 1000, PTC, NTC), which can be configured in the settings (o06).
- Data Communication: For networked systems, the controller can communicate with a master gateway/system manager, allowing for coordinated defrost, night setback, and light control. The address of the controller can be set (o03) for network integration.
- External Display Support: The EKC 302 can connect to an external display, which is useful for standalone applications or when the main controller is not easily accessible.
- Electric Noise Management: Recommendations are provided for cable routing to minimize electric noise interference, such as using separate cable trays and maintaining a minimum distance between sensor/DI/data communication cables and other electric cables.
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