Method of compressor staging for multi-compressor multi-circuited

Abstract

A method of staging and modulating compressors in a multi-circuited refrigeration system including a plurality of condensing heat exchange circuits where each condensing heat exchange circuit includes a plurality of compressors. The method comprises the steps of: accumulating a first operative condition for each compressor; accumulating a second operative condition for each compressor; determining the status of each compressor in each circuit and designating therefrom a first list of circuits having compressors available to be turned on and a second list of circuits having compressors available to be turned off. The method also comprises the steps of: initiating operation of the compressor from the first list with the lowest accumulation of the first operative condition whenever the system calls for an increase in capacity; terminating operation of the compressor from the second list having the greatest accumulation of the second operative condition whenever the system calls for a decrease in capacity; determining the number of compressors which should be modulating; and modulating, subject to the modulating compressor number determining step, the compressors necessary to meet the modulating compressor number in accordance with the greatest accumulation of the second operative condition.