Operation; Data Communication - Danfoss AK-PC 551 User Manual

Introduction
Application
The controller is used for capacity regulation of compressors
and condensers in small refrigeration applications. A maximum of
8 compressors and one condenser can be regulated. For example:
• One suction group + one condenser group
• Two suction groups + one shared condenser (max. 4 + 4 steps)
• One compressor group, max. 8 steps
• One condenser group, max. 8 steps
Advantages
• Energy savings via:
- Optimisation of suction pressure
- Night time increase
- Floating condensing pressure
- Load limitation
Input and output
There are a limited number of available inputs and outputs.
For each signal type, though, the following can be connected:
• Analogue inputs, max. 8 pcs.
Signal from pressure transmitters, temperature sensors,
voltage signal, etc.
• Digital inputs, max. 8 pcs.
Signal from automatic safety control, day/night signal, etc.
• Relay outputs, max. 6 pcs.
Connection of compressors, condenser fans
• Solid state outputs, max. 2 pcs.
- Control of capacity valve on a Copeland digital scroll
- Control of unloader on a Copeland stream compressor.
- Control of both unloaders on a Bitzer CRII
If the outputs are not used for these functions, they can be used
as ordinary relay outputs
• Analogue outputs, max. 2 pcs.
Speed control of compressors or condenser fans.

Operation

The daily operation can be set up directly on the controller or
via an external display device.
During set-up, the display images will be adjusted so that only
the relevant images are opened for additional setting and
end-user operation.
The operation is password protected, and three levels of
access can be granted.
The controller contains several languages. Select the preferred
language at start-up.

Data communication

The controller has built-in modbus data communication, and it
can be connected to an AK-SM 800 type system device.
2 User Guide RS8GY302 © Danfoss 2015-06 AK-PC 551