The Danfoss AK-CC 750A is a comprehensive controller designed for evaporator control in commercial refrigeration appliances and freezing rooms. It serves as a complete regulating unit when combined with valves and sensors, replacing various automatic controls such as day/night thermostats, defrost, fan control, rail heat control, alarm functions, light control, and solenoid valve control. The controller is equipped with data communication capabilities and is primarily operated via a PC using the "AK-Service Tool" software.
Function Description:
The AK-CC 750A's core function is to optimize evaporator operation for energy efficiency. It can control 1 to 4 evaporator sections and features adaptive superheat control for optimal evaporator usage across all operational circumstances. Electronic injection is supported with AKV or stepper valves, and traditional temperature regulation can be achieved using on/off or modulating control of solenoid valves for both DX and indirect brine systems. The controller utilizes a weighted thermostat and alarm thermostat for precise temperature management.
A key feature is its adaptive defrosting function, which monitors ice formation on the evaporator using injection valve opening degrees as a mass flow sensor. This allows the controller to cancel unnecessary planned defrosts and initiate additional automatic defrost cycles if the evaporator is at risk of becoming blocked by ice, thereby reducing service calls.
Other functions include an appliance cleaning function, light control based on door switch or network signals, rail heat pulsing depending on day/night operation or dew point, and monitoring of door alarms. It also provides a log function for recording historical parameter values and alarm modes. The controller can signal other controllers about operating conditions, such as forced closing of expansion valves or alarm messages.
Important Technical Specifications:
The AK-CC 750A controller module has 11 analog inputs and 8 digital outputs (4 solid state, 4 relay). It operates on a 24 V d.c. / a.c. +/- 20% supply voltage, with a power consumption of 8 VA for the controller itself.
- Analog Inputs:
- Pt 1000 ohm /0°C and PTC 1000 ohm /0°C sensors: Resolution 0.1°C, accuracy +/- 0.5°C (between -50°C and +50°C), +/- 1°C (between -100°C and -50°C), +/- 1°C (between +50°C and +130°C).
- Pressure transmitters (AKS 32R / AKS 2050 / AKS 32 (1-5 V)): Resolution 1 mV, accuracy +/- 10 mV. Max. 5 pressure transmitters per module.
- Voltage signal 0-10 V.
- Contact function (On/Off): On at R < 20 ohm, Off at R > 2K ohm.
- On/Off Supply Voltage Inputs:
- Low voltage (0 / 80 V a.c./d.c.): Off: U < 2 V, On: U > 10 V.
- High voltage (0 / 260 V a.c.): Off: U < 24 V, On: U > 80 V.
- Relay Outputs (SPDT):
- AC-1 (ohmic): 4 A.
- AC-15 (inductive): 3 A.
- Voltage: Min. 24 V, Max. 230 V. Low and high voltage must not be connected to the same output group.
- Solid State Outputs:
- Max. 240 V a.c., Min. 48 V a.c.
- Max. 0.5 A, Leak < 1 mA, Max. 1 AKV.
- Stepper Outputs:
- Used for valves with stepper input (20-500 step/s).
- Separate supply to stepper outputs: 24 a.c./d.c./ xx VA.
- Analog Outputs: 0-10 V d.c.
- Ambient Temperature: During transport -40 to 70°C, during operation -20 to 55°C (0 to 95% RH non-condensing).
- Enclosure: PC / ABS material, IP10, VBG 4 density. Mounts on panel wall or DIN rail.
- Weight: Modules in 100-/200-/controller-series: Approx. 200 g / 500 g / 600 g.
- Approvals: EU low voltage directive and EMC requirements (LVD tested to EN 60730, EMC tested, Immunity to EN 61000-6-2, Emission to EN 61000-6-3).
Extension Modules: The system is modular, allowing expansion with various extension modules (AK-XM 101A, 102A/B, 103A, 204A/B, 205A/B, 208C, AK-OB 110) to accommodate more inputs/outputs. A plug on the side transmits supply voltage and data communication between modules.
Power Supply Modules: AK-PS 075 (18 VA, 0.75 A) and AK-PS 150 (36 VA, 1.5 A adjustable) provide 24 V d.c. supply for the controller.
Display Modules: EKA 163B/164B (display with/without operation buttons) and MMIGRS2 (graphic display with operation buttons) can be connected for local temperature display and setting. Up to 4 EKA displays can be mounted.
Communication Module: AK-CM 102 allows data communication for external extension modules, interrupting the row of extension modules.
Usage Features:
- Configuration and Operation: Setup and operation are performed via the "AK-Service Tool" software on a PC. The menu displays are dynamic, adapting to the number of connections.
- Network Linking: The controller can be integrated into a LON-network with other Danfoss ADAP-KOOL® refrigeration control systems, allowing remote operation via AKM software.
- User Management: Supports multiple languages and user profiles with varying access levels, from full operation to view-only.
- Light-Emitting Diodes (LEDs): Provide visual feedback on power, communication status, output status, service tool connection, LON network status, I/O extension, alarms, display connection, and service pin activation.
- Log Function: Allows definition and display of desired measurements, with data exportable to Excel or AKM. Real-time trend functions are available for service situations.
- Alarm Management: Provides an overview of active alarms, with options to acknowledge, view detailed information, and upload alarm history.
- Start/Stop Regulation: Regulation can be started and stopped via software or an external start/stop input.
- Forced Control: Software includes an option for forced control, allowing relay outputs on extension modules to be overridden to OFF or ON positions via change-over switches.
- Clock Function: Includes internal clock with summer/winter time change-over, maintained for at least 12 hours during power failure, and updated via network with a system manager.
- Temperature Sensors: Supports Pt 1000 and PTC 1000 sensors, with options for product sensors and extra Saux sensors for general thermostats or monitoring.
- Pressure Transmitters: Supports AKS 32, AKS 32R, AKS 2050, MBS 8250 for evaporating (P0) and condensing (Pc) pressure, and Paux for general pressostats or monitoring.
- Voltage Signals: Accepts 0-10 V inputs for external reference displacement or general monitoring/alarm functions.
- ON/OFF Inputs: Can receive contact signals on analog inputs or voltage signals on low/high voltage extension modules.
- ON/OFF Outputs: Provides relay outputs (SPDT) for functions like defrost, fan motor, light, compressor, alarm, solenoid valve, drain valve, suction line valve, night blind, drip tray heat recovery, and solid-state outputs for AKV valves and frequently switched loads.
- Analog Outputs: 0-10 V signals for valve regulation or EC motor fans.
- Stepper Outputs: Pulse signals for ETS/KVS/CCMT/CTR stepper motors.
Maintenance Features:
- Modular Design: Facilitates easy replacement or addition of modules as system requirements change.
- Diagnostic LEDs: Aid in quick identification of communication errors, power issues, and output statuses.
- Service Tool Software: Provides comprehensive tools for configuration, monitoring, and troubleshooting, including real-time measurements and alarm history.
- Fuse Protection: Each output on AK-XM 204A/B and 205A/B extension modules has a dedicated fuse for protection.
- Configuration Lock: Prevents accidental or unauthorized changes to critical settings once the system is configured and locked.
- Self-Monitoring: The controller performs internal checks upon startup and continuously monitors connections to modules, indicated by the "Status" LED.
- Adaptive Defrosting: Reduces the need for manual intervention by automatically adjusting defrost cycles based on evaporator ice formation.
- Appliance Cleaning Function: Simplifies cleaning procedures by providing a controlled sequence to stop refrigeration and fans.
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