CRII Mechanical capacity control for transcritical compressors
The mechanical capacity control for the 4PTEU– 8CTEU compressors is specially designed for the high pressures and pressure differences in transcritical R744 applications. It enables quasi-stepless capacity control according to the capacity demand of a superior system controller with simple and effective activation by the CM-RC-01 compressor module. This CRII capacity control system is based on the principle of blocked suction. In this case, the gas flow on the suction side to individual cylinder banks is prevented by a control piston. The operating data and control parameters can be monitored and read out via BEST SOFTWARE.
The compressor is operated at constant speed, the speed of the motor correlates directly with the supply frequency. This results in nominal speeds for 4-pole asynchronous motors of
- 1450 min -1 at 50 Hz or
- 1750 min -1 at 60 Hz.
For detailed information on operation with CRII mechanical capacity control, see Technical Information KT-102.
Compressor and motor damage!
Do not combine a frequency inverter with mechanical capacity control of the compressor! Especially at low speed, adequate motor cooling is not guaranteed because refrigerant mass flow is heavily reduced. Certain exceptions for screw compressors are possible in consultation with Bitzer.