Pressure ratio unload logic for a compressor

摘要

A method is disclosed for controlling a discharge pressure of a compressor relative to a suction pressure of the compressor. The discharge pressure and suction pressure of the compressor are monitored and compared with a predetermined maximum pressure ratio of discharge pressure to suction pressure. If the pressure ratio of discharge pressure to suction pressure exceeds a predetermined pressure ratio limit less than the maximum pressure ratio, a controller unloads the compressor. The predetermined pressure ratio limit is determined relative to the measured suction pressure. The discharge pressure and suction pressure are further monitored and the compressor is inhibited from being reloaded for a predetermined time delay. After the predetermined time delay has elapsed, the compressor is reloaded only if i) the discharge pressure falls below a predetermined reload pressure and ii) the chiller system requires additional cooling capacity.

主权项

1. A method for controlling a discharge pressure of a compressor relative to a suction pressure of the compressor, the method comprising the steps of:
measuring a discharge pressure and a suction pressure of the compressor; determining a predetermined maximum discharge pressure for the compressor based on the measured suction pressure, wherein the predetermined maximum discharge pressure is less than a maximum rated discharge pressure for the compressor; comparing the measured discharge pressure with the predetermined maximum discharge pressure; unloading the compressor in response to the measured discharge pressure exceeding the predetermined maximum discharge pressure; and after unloading the compressor, enabling reloading of the compressor in response to the measured discharge pressure being less than a predetermined reload pressure for the compressor, the predetermined reload pressure being based on the measured suction pressure.