Danfoss Optyma™ Plus Controller User Guide

Introduction

Application

Condensing unit control.

Advantages

• Condensing pressure control in relation to outside temperature
• Fan variable speed regulation
• On/off or variable speed regulation of the compressor
• Heating element control in crankcase
• Day/night controller operation
• Built-in clock function with power reserve
• Built-in Modbus data communication
• Monitoring discharge temperature td
• Oil return management control at variable speed control

Principle

The controller receives a signal for demanded cooling and starts the compressor. If the compressor is controlled by variable speed, the suction pressure (converted to temperature) is controlled according to a set temperature value. Condenser pressure regulation is performed based on a signal from the ambient temperature sensor and the set reference. The controller then manages the fan to maintain the condensing temperature at the desired value. It can also control the crankcase heating element to keep oil separate from the refrigerant. For excess discharge temperature, liquid injection is activated in the suction line (for compressors with this option).

Functions

• Control of condensing temperature
• Control of fan speed
• On/off control or speed regulation of the compressor
• Control of heating element in crankcase
• Liquid injection into economizer port (if possible)
• Raising the condenser pressure regulation reference during night operation
• External start/stop via DI1
• Safety cut-out activated via signal from automatic safety control

Regulation reference for condensing temperature

The controller manages the condensing reference, which is the difference between condensing temperature and ambient temperature. The setpoint can be adjusted using the middle, upper, and lower buttons. The reference can be raised at night to allow slower fan speeds and reduce fan noise via the night set back feature. This setting can be changed without entering programming mode, so caution is advised.

Day/Night

The controller has an internal clock that switches between daytime and night operation. During night operation, the reference is raised by the 'Night offset' value. This day/night signal can also be activated via an on/off input signal (DI2) or data communication.

Fan Operation

The controller manages the fan to maintain the condensing temperature above the outdoor temperature. Users can select fan control methods:

• Internal speed regulation: Fan is speed-controlled via terminal 5-6. At 95% demand and above, relay on terminal 15-16 activates, and 5-6 deactivates.
• External speed regulation: For larger fans, external speed control connects to terminal 54-55. A 0-10V signal indicates desired speed. Relay on terminal 15-16 is active during fan operation. The choice between internal and external control is set in menu 'F17'.

Fan speed at start

When restarting after an idle period, the fan starts at the 'Jog Speed' for 10 seconds, then adjusts to the regulation need.

Fan speed at low loads

At loads between 10% and 30%, the speed remains at the 'FanMinSpeed' setting.

Fan speed at low ambient temperatures

To prevent frequent start/stops in low ambient temperatures where fan capacity is high, the internal amplification factor is lowered for smoother regulation. The 'Jog speed' is also lowered between 10°C and -20°C. Below -20°C, 'Jog Low' can be used.

Compressor compartment pre-ventilation

The condenser fan operates for a period before compressor start, particularly for mildly flammable refrigerants (e.g., A2L types), to create a safe atmosphere by removing potential flammable gas from the compartment. A fixed delay of approximately 8 seconds occurs between pre-ventilation and compressor start to reduce airflow and prevent low ambient temperature issues.

Compressor Control

The compressor is controlled via the DI1 input. It starts when the input is connected. Three restrictions prevent frequent starts/stops: minimum ON time, minimum OFF time, and time between starts. These have priority over other functions. A 'locked' status indicates a restriction is active. If DI3 is used as a safety stop, an insufficient signal immediately stops the compressor. Variable speed compressors can be controlled via a voltage signal at the AO2 output. For compressors running long periods at low speed, speed is briefly increased for oil return.

Maximum discharge gas temperature

The Td sensor measures discharge gas temperature. If variable speed control is used, capacity is reduced as Td approaches the maximum set value. If the temperature exceeds the set maximum, the fan runs at 100%. If the temperature doesn't drop after a set delay, the compressor stops. It will only restart 10 K below the cut-out limit, after its off-timer expires. Setting the delay time to '0' disables this function. The Td sensor can be deactivated (063).

Liquid injection into economizer port

The controller can activate liquid injection into the economizer port if the discharge temperature nears the maximum allowable temperature. This function uses the Aux Relay if configured.

High pressure monitoring

The internal high pressure monitoring detects over-limit condensing pressure to allow regulation to continue. If setting c73 is exceeded, the compressor stops, and an alarm is triggered. If the signal comes from the DI3 safety circuit, the compressor stops immediately, and the fan sets to 100%. Regulation resumes when the DI3 signal is 'OK'.

Low pressure monitoring

The internal low pressure monitoring cuts out the compressor if suction pressure falls below the lower limit, after the minimum ON time is exceeded. An alarm (A2) is issued. This function is time-delayed for compressors starting at low ambient temperatures.

Pump down limit

The compressor stops if suction pressure falls below the set value, after the minimum ON time is exceeded.

Heating Element in the Crankcase

The controller includes a thermostat function to control the crankcase heating element, preventing oil from mixing with refrigerant. This function is active when the compressor is stopped and is based on ambient and suction gas temperatures. Power is supplied when these temperatures are equal ± a temperature difference. The 'CCH off diff' setting determines when power is cut, and 'CCH on diff' when 100% power is supplied. The controller calculates wattage and cycles the element. The Taux sensor can measure crankcase temperature. The heating element is set to 100% if Taux is lower than Ts + 10 K and ambient temperature is below 0°C.

Separate thermostat function

The Taux sensor can also be used for a heating function with programmable temperature, activating the AUX relay to connect the heating element.

Digital Inputs

Two digital inputs (DI1, DI2) have contact functions, and one (DI3) uses a high voltage signal. They serve various purposes:

• DI1: Starts and stops the compressor.
• DI2: User-selectable functions, including external safety, main switch, night setback, separate alarm, input signal monitoring, or external speed control.
• DI3: Safety signal from low/high-pressure switch.

Data Communication

The controller features built-in MODBUS data communication. A LON RS485 module can be inserted for alternative communication, connecting via terminal RS485. All data communication connections must adhere to cable requirements specified in literature RC8AC.

Display

The controller supports an external display, such as EKA 163B (readings only) or EKA 164B (readings and operation), with a maximum cable length of 15 meters. A setting allows selection between displaying suction pressure (Ts) or condensing pressure (Tc). The other value can be viewed by pressing the lower button. For MODBUS connection, displays with Index A are recommended. The controller's address must be greater than 0 for display communication. Two displays can be connected: one to the plug and another to the fixed data communication.

Override

The controller supports an override function, usable with a master gateway or system manager.

Survey of Functions

The controller offers various functions configurable via parameters. Key functions include:

• Normal display: Shows Ts or Tc.
• Thermostat: Setpoint adjustment, unit selection (°C/°F), start/stop control (internal or external), night setback, reference Ts/Tc settings.
• External heating function: Thermostat cut-in for external heating elements.
• Condensing temperature limits: Minimum and maximum permitted references.
• Maximum discharge gas temperature: Sets the limit for Td, triggering fan speed increase and potential compressor stop.
• Alarms: Configurable delays and limits for DI2, high condensing temperature, and A80 alarms.
• Compressor Control Parameters: Extensive settings for ON/OFF times, start/stop logic, speed control, pressure limits, liquid injection, and more.
• Fan Control Parameters: Settings for fan speed, regulation, jog speeds, control modes, and limits.
• Real time clock: For day/night switching and clock settings.
• Miscellaneous: Network address configuration.

Detailed parameter settings are available in the 'Menu Survey' section.

Access Code

An access code (0-100) can be set to protect controller settings. A value of 99 grants immediate access.

Controller Software Version

Displays the current software version of the controller.

Select Signal for Display

Allows selection of the primary signal displayed: 1 for Suction pressure (Ts) or 2 for Condensing pressure (Tc).

Pressure Transmitter Settings

Configuration for pressure transmitters (Ps and Pc) including working range (min/max values).

Refrigerant Setting

Defines the refrigerant type used (e.g., R22, R134a, R404A, etc.). Incorrect selection can damage the compressor. User-defined options are available with specific factor settings.

Digital Input Signal - DI2

Configures the function of DI2, which can be used for safety circuits, main switch control, night operation, alarm functions, monitoring, or external speed control.

Aux Relay Function

Defines the purpose of the auxiliary relay, such as external heating, liquid injection, or oil return management.

Unit Type

Specifies the condensing unit type. This setting is factory-set and locked after the first configuration, ensuring compatibility with the selected refrigerant.

S3 Configuration

Determines if the S3 input is used for measuring discharge temperature.

Save as Factory Setting

Allows saving the current controller settings as a new factory default.

Define the Use of the Taux Sensor

Specifies the function of the Taux sensor, which can be for oil temperature measurement, external heating function, or other optional temperature measurements.

Operating Times

Readouts are available for the operating time of the condensing unit, compressor, and crankcase heating element. These values are multiplied by 1,000 to get the actual time.

Alarm Counts

Counters track the number of High Pressure (HP) alarms, Low Pressure (LP) alarms, discharge temperature (Td) alarms, and blocked condenser alarms.

Oil Return Management

Settings for managing oil return, including speed limits, time counters, and boost speed/time parameters.

Service

Provides readouts for various operational parameters, including pressures (Pc, Ps), temperatures (Taux, S6, Tamb, Td, Ts), status of digital inputs and relays, compressor capacity, and analog output voltages.

Operating Status

The controller displays status codes (S0, S2, S3, S10, S25, S26, S34) indicating its current operational state, such as normal regulation, waiting periods, or safety stops. Other displays include password status, main switch regulation status, and refrigerant/unit type selection status.

Fault Message

In case of errors, LEDs flash, and the alarm relay activates. Error reports are categorized as A-alarms (delayed visibility) and E-alarms (immediate visibility). Messages include LP alarm, no refrigerant selected, DI2 alarm, HP alarm, standby mode, condenser blocked, max discharge temperature, safety alarm, drive alarm, and various sensor/controller errors. Actions for each fault are provided.

Operation

Display

Values are shown with three digits, and a setting determines temperature display in °C or °F.

Light-emitting diodes (LED) on front panel

LEDs indicate operational status: Refrigeration (lit), Heating element in crankcase (lit), Fan running (lit). LEDs flash during an alarm. Error codes can be viewed and acknowledged via the upper button.

The Buttons

Upper and lower buttons adjust values. Accessing the menu requires pressing the upper button for a few seconds to enter parameter codes. The middle button is used to select parameters and confirm values. Changes are saved by pressing the middle button again. The display reverts to the default Ts/Tc after 20-5 seconds of inactivity.

Set point

Press the middle button to show the temperature value, then use upper/lower buttons to adjust. Press the middle button again to confirm.

Reading the temperature

A short press of the lower button displays the alternate temperature (Ts or Tc).

Get a good start

A quick setup procedure involves opening parameter r12 to stop regulation (or confirming it's at 0 for new units), selecting the refrigerant (parameter o30), starting regulation via r12 and DI1/DI2, reviewing factory settings, and configuring network address (o03) if applicable.

Menu Survey

This section provides a comprehensive overview of controller parameters, their codes, ranges, and factory/actual settings. Key parameter categories include Normal Operation, Regulation, Alarms, Compressor, Control Parameters, Fan, Real Time Clock, and Miscellaneous.

Specific parameters like 'Min. ON-time' (c01), 'Max. compressor speed' (c48), 'Definition of compressor control mode' (c71), 'Min. suction pressure' (c75), 'Fan speed' readout (F07), and 'Refrigerant setting' (o30) are detailed with their respective ranges and default values.

Connections

The controller features various terminals for inputs, outputs, and communication:

• DI1, DI2: Digital inputs for start/stop, safety functions, or external control signals.
• Pc, Ps: Connections for pressure transmitters (0-32 bar and -1 to 12 bar respectively).
• S2, S3, S4, S5, S6: Inputs for temperature sensors (Ambient, Discharge Gas, Suction Gas, and extra temperature measurements).
• EKA Display: Port for connecting an external display unit.
• RS485: Terminal for data communication modules (e.g., LON).
• AO1, AO2: Analog outputs (0-10V) for fan and compressor speed control.
• MODBUS: Integrated terminal for MODBUS communication.
• Supply voltage: 230V AC connection.
• FAN: Connection for the fan, speed controlled internally.
• Alarm: Connection for alarm signals.
• Comp: Connection for compressor status.
• CCH: Connection for the crankcase heating element.
• Fan (terminals 15-16): Connection for fan speed increase above 95%.
• Aux: For liquid injection, external heating, or oil return functions.
• DI3: Digital input for low/high pressure monitoring (0/230V AC).

Electric noise precautions recommend keeping sensor, DI, and data communication cables separate from other electrical cables, maintaining at least 10 cm distance.

Installation Considerations

Proper installation is crucial to prevent malfunctions. Electronic controls complement, but do not replace, good engineering practice. Installers are responsible for thorough installation checks and safety devices, including signals for compressor stop and liquid receivers.

Data

Key technical specifications include:

• Supply voltage: 230 V AC ±10/-15%.
• Sensors: Pt 1000 for temperature, Ratiometric transmitters for pressure.
• Accuracy: Varies by sensor type and temperature range.
• Display: LED, 3-digits; external EKA displays supported.
• Digital Inputs: DI1/DI2 require gold plating, max 15m cable; DI3 for 230V AC safety.
• Electrical connection cable: Max 1.5 mm² multi-core.
• Triac output: For Fan control.
• Relays: Comp, CCH (4A), Alarm, Fan, Aux (4A).
• Analog output: 2 pcs. 0-10V DC.
• Environments: Operating (-25 to 55°C), Transport (-40 to 70°C), Humidity (20-80% Rh).
• Mounting: DIN-rail or wall.
• Weight: 0.4 kg.
• Data communication: MODBUS, LON.
• Power reserve for clock: 4 hours.
• Approvals: CE marked (LVD, EMC).

Ordering

The Optyma™ Plus condensing unit controller is available with various accessories and configurations: