Bock CO2 compressors with LSPM motors
GERMANY: Bock is expanding its transcritical CO2 compressor portfolio with a new series featuring line start permanent magnet (LSPM) motor technology.
The LSPM compressors for use in refrigeration and heat pump systems are said to combine the strengths of robust squirrel-cage asynchronous motors and those of synchronously running permanent magnet motors.
After asynchronous starting, the motor synchronises to the operating frequency and then runs in synchronous mode without slippage. This simultaneous motor running achieves a higher refrigerant mass flow with an optimised speed and thus more cooling or heating capacity, says Bock.
Since there are no power losses in the rotor, the motor and overall compressor efficiency is increased by an average of about 6% compared to a standard asynchronous motor. Operation can be flexible, either directly from the mains or via a frequency inverter.
The compressors launch this month with three compressor sizes offering a total of 16 displacement stages from 4.8 to 39.5m3/h (50Hz/1,500 rpm). This covers a wide range of capacities, with one compressor each ranging from 9 to 89kW in medium temperature cooling and 27 to 188kW in heating.