Parallel Condensing Unit Control System And Method

Abstract

A system comprises a condenser for a refrigeration system and a control module. The condenser has a plurality of variable speed condenser fans. The control module controls the plurality of variable speed condenser fans. The control module increases condenser fan operation by activating a deactivated variable speed condenser fan at a first fan speed when at least one variable speed condenser fan of the plurality is deactivated and by increasing a fan speed of an activated variable speed condenser fan to a second fan speed when each variable speed condenser fan of the plurality is activated and operating at the first fan speed. The second fan speed is faster than the first fan speed.

1 . A system comprising:
 a condenser for a refrigeration system, said condenser having a plurality of variable speed condenser fans;   a control module controlling said plurality of variable speed condenser fans, said control module increasing condenser fan operation by activating a deactivated variable speed condenser fan at a first fan speed when at least one variable speed condenser fan of said plurality is deactivated and by increasing a fan speed of an activated variable speed condenser fan to a second fan speed when each variable speed condenser fan of said plurality is activated and operating at said first fan speed, said second fan speed being faster than said first fan speed.   
     
     
         2 . The system of  claim 1  wherein said control module increases condenser fan operation by increasing a fan speed of an activated variable speed condenser fan from said first fan speed to said second fan speed when each variable speed condenser fan of said plurality is activated and when at least one variable speed condenser fan of said plurality is operating at said first fan speed and each remaining variable speed condenser fan of said plurality is operating at one of said first fan speed and said second fan speed. 
     
     
         3 . The system of  claim 1 , wherein said control module decreases condenser fan operation by decreasing a fan speed of an activated variable speed condenser fan from said second fan speed to said first fan speed when each variable speed condenser fan of said plurality is operating at said second fan speed. 
     
     
         4 . The system of  claim 1 , wherein said control module decreases condenser fan operation by decreasing a fan speed of an activated variable speed condenser fan from said second fan speed to said first fan speed when at least one variable speed condenser fan of said plurality is operating at said second fan speed and each remaining variable speed condenser fan of said plurality is operating at one of said first fan speed and said second fan speed. 
     
     
         5 . The system of  claim 1 , wherein said control module decreases condenser fan operation by deactivating an activated variable speed condenser fan when each variable speed condenser fan of said plurality is operating at said first fan speed. 
     
     
         6 . The system of  claim 1 , further comprising a discharge pressure sensor that generates a discharge pressure signal based on a discharge pressure of said condenser, wherein said control module compares said discharge pressure to a set point and controls condenser fan operation based on said comparison. 
     
     
         7 . A method comprising:
 controlling, with a control module, a fan speed for each variable speed condenser fan of a condenser for a refrigeration system, said condenser having a plurality of variable speed condenser fans;   increasing condenser fan operation of said condenser, with said control module, by activating a deactivated variable speed condenser fan at a first fan speed when at least one variable speed condenser fan of said plurality is deactivated and by increasing a fan speed of an activated variable speed condenser fan to a second fan speed when each variable speed condenser fan of said plurality is activated and operating at said first fan speed, said second fan speed being faster than said first fan speed.   
     
     
         8 . The method of  claim 7  further comprising increasing condenser fan operation, with said control module, by increasing a fan speed of an activated variable speed condenser fan from said first fan speed to said second fan speed when each variable speed condenser fan of said plurality is activated and when at least one variable speed condenser fan of said plurality is operating at said first fan speed and each remaining variable speed condenser fan of said plurality is operating at one of said first fan speed and said second fan speed. 
     
     
         9 . The method of  claim 7 , further comprising decreasing condenser fan operation, with said control module, by decreasing a fan speed of an activated variable speed condenser fan from said second fan speed to said first fan speed when each variable speed condenser fan of said plurality is operating at said second fan speed. 
     
     
         10 . The method of  claim 7 , further comprising decreasing condenser fan operation, with said control module, by decreasing a fan speed of an activated variable speed condenser fan from said second fan speed to said first fan speed when at least one variable speed condenser fan of said plurality is operating at said second fan speed and each remaining variable speed condenser fan of said plurality is operating at one of said first fan speed and said second fan speed. 
     
     
         11 . The method of  claim 7 , further comprising decreasing condenser fan operation, with said control module, by deactivating an activated variable speed condenser fan when each variable speed condenser fan of said plurality is operating at said first fan speed. 
     
     
         12 . The method of  claim 7 , further comprising comparing a received discharge pressure to a set point and controlling condenser fan operation, with said control module, based on said comparing. 
     
     
         13 . A system comprising:
 a condenser for a refrigeration system, said condenser having a plurality of condenser fans including a first variable speed condenser fan and a fixed speed condenser fan;   a control module controlling said plurality of condenser fans, said control module increasing condenser fan operation, when said plurality of condenser fans are deactivated, by activating said first variable speed condenser fan, and said control module increasing condenser fan operation by increasing a fan speed of said first variable speed condenser fan to a maximum fan speed prior to activating said fixed speed condenser fan.   
     
     
         14 . The system of  claim 13 , said plurality of condenser fans including a second variable speed condenser fan, said control module increasing condenser fan operation by increasing a fan speed of said second variable speed condenser fan to a maximum fan speed prior to activating said fixed speed condenser fan. 
     
     
         15 . The system of  claim 13 , further comprising a discharge pressure sensor that generates a discharge pressure signal based on a discharge pressure of said condenser, wherein said control module compares said discharge pressure to a set point and controls said plurality of condenser fans based on said comparison. 
     
     
         16 . A method comprising:
 controlling, with a control module, a plurality of condenser fans of a condenser for a refrigeration system, said plurality of condenser fans including a first variable speed condenser fan and a fixed speed condenser fan;   increasing condenser fan operation, when said plurality of condenser fans are deactivated, by activating, with said control module, said first variable speed condenser fan;   increasing condenser fan operation by increasing, with said control module, a fan speed of said first variable speed condenser fan to a maximum fan speed prior to activating, with said control module, said fixed speed condenser fan.   
     
     
         17 . The method of  claim 16 , said plurality of condenser fans including a second variable speed condenser fan, said method further comprising:
 increasing, with said control module, a fan speed of said second variable speed condenser fan to a maximum fan speed prior to activating said fixed speed condenser fan.   
     
     
         18 . The method of  claim 16 , further comprising comparing a received discharge pressure to a set point and controlling condenser fan operation, with said control module, based on said comparing.