Danfoss Optyma AK-RC 251

Installation Guide
Temperature controller for walk-in coolers
and freezers, Type AK-RC 251
© Danfoss | DCS (vt) | 2021.02
AN36292867744601-000101 | 1
080R9291
A N36292867744601-000101
Warnings
• Using the unit without observing the manufacturer's instructions may alter the appliance's safety requirements. Only NTC probes
supplied by Danfoss should be used for the unit to operate correctly.
• From -40 – +68 °F, if the NTC probe is extended to 3,280 ft with at least 20AWG cable, the maximum deviation will be 0.45 °F.
• It should be installed in a place protected from vibrations, water and corrosive gases, where the ambient temperature does not
exceed the value indicated in the technical data.
• For the reading to be correct, the probe should be used in a place without heat influences apart from the temperature you want to
measure or control.
• IP65 protection degree is only valid with the protection cover closed.
• IP65 protection degree is only valid if the cables enter the device using electrical conduit + gland with IP65 or above. The size of the
glands should be suitable for the diameter of the conduit used.
• Do not spray the unit directly with high-pressure hoses, as this could cause damage.
IMPORTANT:
• Before starting the installation, you must take the advice of local regulations in force.
• The AUXILIARY relays are programmable, and their operation depends on the configuration.
• The function of the digital inputs depends on the configuration.
• The recommended currents and powers are the maximum working currents and powers.
EN : Temperature controller for walk-in coolers and freezers
ES : Controlador de temperatura para cuartos fríos y congeladores
Type AK-RC 251
Wiring
Always disconnect the power supply to do the wiring.
The probes and their cables should NEVER be installed in a conduit together with power, control or power supply cables.
For disconnection, the power supply circuit must be equipped with a switch of at least 2 A, 230 V, located near the device. The power
supply cable will be H05VV-F or NYM 1x16/3. The section to be used as wire rated according to local regulations but must never be
less than 14AWG.
Cables for relay or contactor outputs should use 14AWG, allow working temperatures equal to or over 158 °F and be installed with as
few bends as possible.
The 120/230 V~ wiring must be kept clear of any other external element.
The wiring to be done depends on the type of installation. Use the appropriate diagram based on the option selected in the
wizard. Check the available options on the diagrams included in the controller's packaging.
Wizard refers to a built in tool to guide the user through the set up process.
Maintenance
• Clean the surface of the unit with a soft cloth, water and soap.
• Do not use abrasive detergents, gasoline, alcohol or solvents, as this might damage the unit.
ENGLISH

Danfoss Optyma AK-RC 251 Specifications

General

Digital inputs	2
Analogue inputs	1
Power consumption	3 VA
Housing material	Plastic
Weight	0.2 kg
Control outputs	Relay
Application	Refrigeration
Type	Electronic controller
Switching capacity	8 A (resistive load)
Sensor input	PTC/NTC

Summary

Installation and Safety Precautions

Warnings and Important Notes

Key safety measures, probe usage, installation environment, IP rating, local regulations, and operational clarifications.

Wiring and Maintenance Guidelines

Instructions for safe electrical connections, cable handling, and proper unit cleaning procedures.

Keypad and Indicator Functions

Explains the operation of each button and the meaning of various display icons for status and alarms.

Initial Configuration Wizard

Guides through the initial setup process, including installation type selection and temperature setpoint configuration.

Unit Configuration and Parameters

Programming Menu Access

Details how to access Condensed (3s SET) and Extended (6s SET) programming menus for configuration.

Parameter Settings and Control

Lists parameters for temperature setting, calibration, differentials, and locking values for regulation.

Defrost Configuration

Covers parameters related to defrost frequency, duration, type, and associated messages.

Evaporator Fan Control

Details parameters for fan shutdown temperature, differential, and status during defrost.

Alarm Configuration

Explains parameters for temperature alarms, delays, external alarms, and door open alarms.

Basic Configuration Options

Covers parameters for power supply delay, light timing, password function, and communication settings.

Inputs and Outputs Configuration

Details configuration for connected probes, digital inputs, polarities, and auxiliary relays.

HACCP Alarm Settings

Defines parameters for maximum temperature and permitted time for HACCP alarm activation.

Information and Specifications

Information Retrieval

Details on reading parameters like wizard option, program version, bootloader, and parameter map.

Controller Messages

Lists common error messages, alarm codes (Pd, LP, E1/E2/E3, AH, AL, AE, AES, Adt, HCP), and their meanings.

Technical Specifications

Provides detailed specifications including power supply, current ratings, probe range, precision, and environmental limits.

Ordering Information

Lists controller models, available accessories like NTC sensors, and their respective part numbers.