This application will control the start sequence of 3 compressors. Air pressure is monitored via three pressure switches. The low pressure switch identifies when air pressure has dropped to the level when one compressor is needed to increase the air pressure to normal levels. The ok pressure switch identifies when the pressure has reached the level where compressor operation is no longer required. The over pressure switch identifies an over pressure condition. Compressor sequence is alternated to equalize the operation hours of each compressor as much as possible. The 'Lead' compressor is the compressor that will operate the next time air pressure drops and a compressor is required. The 'Lead' compressor is alternated between all three compressors (once each time pressure drops low and then rises to normal). In the event a single compressor cannot meet the load demand (OK pressure not reached within 10 minutes), a second compressor is started to accomodate the load condition. After an additional 10 minutes without reaching the OK pressure, the third compressor is also started. After 10 minutes with all three compressors started, if the pressure OK has not been reached, the alarm output will pulse on and off in two second intervals. If at any time an over pressure is detected, all compressors will shut down and the alarm output will be on steady.
AN-104.pdf, Application Programs AN-104_EBB.dld, AN-104_HEC.dld, AN-104_PCS.dld, AN-104_SI.dld