6
The refrigerant is circulated in a completely closed system in the following order: Evaporator, Compressor, Condenser,
and last expansion valve. The compressor keeps a low pressure in the evaporator, the refrigerants boiling point is there-
by lowered and the incoming refrigerants from the expansion valve is vaporized (boiling) with absorption of heat as a
result. The heat is taken from the supply air when passing the evaporator - supply air temperature is lowered. After a
pressure increase in the compressor the refrigerant gas passing the condenser were the gas, thanks to the high pres-
sure and thereby a high boiling point, is transformed into fluid through condensation and thereby heat emission. The
heat is submitted to the exhaust air that passing the condenser. The heat has accordingly been transferred from supply
air to exhaust air. After leaving the condenser in liquid state the refrigerant passes the expansion valve who controls
the amount of refrigerants to the evaporator and thereby the cycle is completed.
6.2
Components and function
6.2.1
Compressor
The compressor in Topvex Soft Cooler is a high-efficiency, variable speed scroll compressor. It is designed especially for
speed control and can not run without frequency converter. Speed and by that cooling capacity is regulated by changing
the operating frequency, the maximum working range of the compressor is no less than 20 to 120 rps (revolutions per
second). In the smaller unit sizes the maximum frequency is limited via a setting in the frequency converter. Controlling
of the compressor is completely automatic according to the need of the premises and the signal comes via the control
unit to the frequency converter.
6.2.2
Frequency converter (FC)
The compressors frequency converter is located in the electrical cabinet. The programmable controller receives a con-
trol signal (0-10 V DC) corresponding to the current cooling load from the control unit and then, via frequency convert-
er, regulates the compressors speed according to the actual cooling load. The programmable controller has also a high
pressure sensor (HPS) (4-20 mA) connected. This sensor continuously measuring the pressure in the cooling system. If
the pressure exceeds the set value in the programmable controller the output frequency is reduced and thereby the
compressors speed will be reduced so that the pressure will not rise to the level were the high pressure switch (PSH)
on the high pressure side will trigger. The compressor is protected from fast start and stops by an restart delay function
(3 minutes) in the programmable controller.
6.2.2.1 Integrated control, quick guide
FLSTDmCOMM is the CAREL solution for the management of a BLDC compressor via Power+ inverter.
The FLSTDmCOMM software installed on the programmable board features:
• Easy-to-use add-on to manage BLDC compressor by Power+ inverter via an analogue signal (0-5V/0-10V) or con-
trolled via Modbus serial communication
• Full control of compressor working conditions, tested and approved by compressor manufacturers
• Use of electronic expansion valve manage via EVD EVO on-board (unipolar valve)
• No need of user interface (pGD1) when connecting to a BMS Modbus
• Energy saving and consequently cost savings, by integrated unit
• Improvement in system management, managed using a semi-graphic user interface (pGD1)
208766 | A003
