Method and apparatus for detecting surge in centrifugal compressors driven by electric motors.

摘要

@ A surge detection apparatus for use in a refrigeration system having a centrifugal compressor (12) driven by an electric motor (20) includes a first pressure transducer (32) for sensing a condenser pressure and a second pressure transducer (34) for sensing an evaporator pressure. A first bandpass digital filter (58) responsive to the condenser pressure and the evaporator pressure is provided for generating a first signal representative of the rate of change of the pressure developed across the compressor. A current transformer (24) is used to sense a current in the electric motor driving the compressor. A second bandpass digital filter (61) responsive to the motor current is provided for generating a second signal representative of the rate of change of the RMS current being drawn by the compressor drive motor. A third signal representative of a differential pressure threshold and a fourth signal representative of a first motor current threshold and a second motor current threshold are provided. A computing device (73) responsive to the first through fourth signals indicates when a valid surge is occurring in the compressor.